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rfc:rfc7515

Internet Engineering Task Force (IETF) M. Jones Request for Comments: 7515 Microsoft Category: Standards Track J. Bradley ISSN: 2070-1721 Ping Identity

                                                           N. Sakimura
                                                                   NRI
                                                              May 2015
                      JSON Web Signature (JWS)

Abstract

 JSON Web Signature (JWS) represents content secured with digital
 signatures or Message Authentication Codes (MACs) using JSON-based
 data structures.  Cryptographic algorithms and identifiers for use
 with this specification are described in the separate JSON Web
 Algorithms (JWA) specification and an IANA registry defined by that
 specification.  Related encryption capabilities are described in the
 separate JSON Web Encryption (JWE) specification.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc7515.

Jones, et al. Standards Track [Page 1] RFC 7515 JSON Web Signature (JWS) May 2015

Copyright Notice

 Copyright (c) 2015 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

Table of Contents

 1. Introduction ....................................................4
    1.1. Notational Conventions .....................................4
 2. Terminology .....................................................5
 3. JSON Web Signature (JWS) Overview ...............................7
    3.1. JWS Compact Serialization Overview .........................7
    3.2. JWS JSON Serialization Overview ............................8
    3.3. Example JWS ................................................8
 4. JOSE Header .....................................................9
    4.1. Registered Header Parameter Names .........................10
         4.1.1. "alg" (Algorithm) Header Parameter .................10
         4.1.2. "jku" (JWK Set URL) Header Parameter ...............10
         4.1.3. "jwk" (JSON Web Key) Header Parameter ..............11
         4.1.4. "kid" (Key ID) Header Parameter ....................11
         4.1.5. "x5u" (X.509 URL) Header Parameter .................11
         4.1.6. "x5c" (X.509 Certificate Chain) Header Parameter ...11
         4.1.7. "x5t" (X.509 Certificate SHA-1 Thumbprint)
                Header Parameter ...................................12
         4.1.8. "x5t#S256" (X.509 Certificate SHA-256
                Thumbprint) Header Parameter .......................12
         4.1.9. "typ" (Type) Header Parameter ......................12
         4.1.10. "cty" (Content Type) Header Parameter .............13
         4.1.11. "crit" (Critical) Header Parameter ................14
    4.2. Public Header Parameter Names .............................14
    4.3. Private Header Parameter Names ............................14
 5. Producing and Consuming JWSs ...................................15
    5.1. Message Signature or MAC Computation ......................15
    5.2. Message Signature or MAC Validation .......................16
    5.3. String Comparison Rules ...................................17
 6. Key Identification .............................................18

Jones, et al. Standards Track [Page 2] RFC 7515 JSON Web Signature (JWS) May 2015

 7. Serializations .................................................19
    7.1. JWS Compact Serialization .................................19
    7.2. JWS JSON Serialization ....................................19
         7.2.1. General JWS JSON Serialization Syntax ..............20
         7.2.2. Flattened JWS JSON Serialization Syntax ............21
 8. TLS Requirements ...............................................22
 9. IANA Considerations ............................................22
    9.1. JSON Web Signature and Encryption Header
         Parameters Registry .......................................23
         9.1.1. Registration Template ..............................23
         9.1.2. Initial Registry Contents ..........................24
    9.2. Media Type Registration ...................................26
         9.2.1. Registry Contents ..................................26
 10. Security Considerations .......................................27
    10.1. Key Entropy and Random Values ............................27
    10.2. Key Protection ...........................................28
    10.3. Key Origin Authentication ................................28
    10.4. Cryptographic Agility ....................................28
    10.5. Differences between Digital Signatures and MACs ..........28
    10.6. Algorithm Validation .....................................29
    10.7. Algorithm Protection .....................................29
    10.8. Chosen Plaintext Attacks .................................30
    10.9. Timing Attacks ...........................................30
    10.10. Replay Protection .......................................30
    10.11. SHA-1 Certificate Thumbprints ...........................30
    10.12. JSON Security Considerations ............................31
    10.13. Unicode Comparison Security Considerations ..............31
 11. References ....................................................32
    11.1. Normative References .....................................32
    11.2. Informative References ...................................34
 Appendix A.  JWS Examples .........................................36
   A.1.  Example JWS Using HMAC SHA-256 ............................36
     A.1.1.  Encoding ..............................................36
     A.1.2.  Validating ............................................38
   A.2.  Example JWS Using RSASSA-PKCS1-v1_5 SHA-256 ...............38
     A.2.1.  Encoding ..............................................38
     A.2.2.  Validating ............................................42
   A.3.  Example JWS Using ECDSA P-256 SHA-256 .....................42
     A.3.1.  Encoding ..............................................42
     A.3.2.  Validating ............................................44
   A.4.  Example JWS Using ECDSA P-521 SHA-512 .....................45
     A.4.1.  Encoding ..............................................45
     A.4.2.  Validating ............................................47
   A.5.  Example Unsecured JWS .....................................47
   A.6.  Example JWS Using General JWS JSON Serialization ..........48
     A.6.1.  JWS Per-Signature Protected Headers ...................48
     A.6.2.  JWS Per-Signature Unprotected Headers .................49
     A.6.3.  Complete JOSE Header Values ...........................49

Jones, et al. Standards Track [Page 3] RFC 7515 JSON Web Signature (JWS) May 2015

     A.6.4.  Complete JWS JSON Serialization Representation ........50
   A.7.  Example JWS Using Flattened JWS JSON Serialization ........51
 Appendix B.  "x5c" (X.509 Certificate Chain) Example ..............52
 Appendix C.  Notes on Implementing base64url Encoding without
              Padding ..............................................54
 Appendix D.  Notes on Key Selection ...............................55
 Appendix E.  Negative Test Case for "crit" Header Parameter .......57
 Appendix F.  Detached Content .....................................57
 Acknowledgements ..................................................58
 Authors' Addresses ................................................58

1. Introduction

 JSON Web Signature (JWS) represents content secured with digital
 signatures or Message Authentication Codes (MACs) using JSON-based
 [RFC7159] data structures.  The JWS cryptographic mechanisms provide
 integrity protection for an arbitrary sequence of octets.  See
 Section 10.5 for a discussion on the differences between digital
 signatures and MACs.
 Two closely related serializations for JWSs are defined.  The JWS
 Compact Serialization is a compact, URL-safe representation intended
 for space-constrained environments such as HTTP Authorization headers
 and URI query parameters.  The JWS JSON Serialization represents JWSs
 as JSON objects and enables multiple signatures and/or MACs to be
 applied to the same content.  Both share the same cryptographic
 underpinnings.
 Cryptographic algorithms and identifiers for use with this
 specification are described in the separate JSON Web Algorithms (JWA)
 [JWA] specification and an IANA registry defined by that
 specification.  Related encryption capabilities are described in the
 separate JSON Web Encryption (JWE) [JWE] specification.
 Names defined by this specification are short because a core goal is
 for the resulting representations to be compact.

1.1. Notational Conventions

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
 "OPTIONAL" in this document are to be interpreted as described in
 "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119].
 The interpretation should only be applied when the terms appear in
 all capital letters.
 BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per
 Section 2.

Jones, et al. Standards Track [Page 4] RFC 7515 JSON Web Signature (JWS) May 2015

 UTF8(STRING) denotes the octets of the UTF-8 [RFC3629] representation
 of STRING, where STRING is a sequence of zero or more Unicode
 [UNICODE] characters.
 ASCII(STRING) denotes the octets of the ASCII [RFC20] representation
 of STRING, where STRING is a sequence of zero or more ASCII
 characters.
 The concatenation of two values A and B is denoted as A || B.

2. Terminology

 These terms are defined by this specification:
 JSON Web Signature (JWS)
    A data structure representing a digitally signed or MACed message.
 JOSE Header
    JSON object containing the parameters describing the cryptographic
    operations and parameters employed.  The JOSE (JSON Object Signing
    and Encryption) Header is comprised of a set of Header Parameters.
 JWS Payload
    The sequence of octets to be secured -- a.k.a. the message.  The
    payload can contain an arbitrary sequence of octets.
 JWS Signature
    Digital signature or MAC over the JWS Protected Header and the JWS
    Payload.
 Header Parameter
    A name/value pair that is member of the JOSE Header.
 JWS Protected Header
    JSON object that contains the Header Parameters that are integrity
    protected by the JWS Signature digital signature or MAC operation.
    For the JWS Compact Serialization, this comprises the entire JOSE
    Header.  For the JWS JSON Serialization, this is one component of
    the JOSE Header.
 JWS Unprotected Header
    JSON object that contains the Header Parameters that are not
    integrity protected.  This can only be present when using the JWS
    JSON Serialization.

Jones, et al. Standards Track [Page 5] RFC 7515 JSON Web Signature (JWS) May 2015

 Base64url Encoding
    Base64 encoding using the URL- and filename-safe character set
    defined in Section 5 of RFC 4648 [RFC4648], with all trailing '='
    characters omitted (as permitted by Section 3.2) and without the
    inclusion of any line breaks, whitespace, or other additional
    characters.  Note that the base64url encoding of the empty octet
    sequence is the empty string.  (See Appendix C for notes on
    implementing base64url encoding without padding.)
 JWS Signing Input
    The input to the digital signature or MAC computation.  Its value
    is ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' ||
    BASE64URL(JWS Payload)).
 JWS Compact Serialization
    A representation of the JWS as a compact, URL-safe string.
 JWS JSON Serialization
    A representation of the JWS as a JSON object.  Unlike the JWS
    Compact Serialization, the JWS JSON Serialization enables multiple
    digital signatures and/or MACs to be applied to the same content.
    This representation is neither optimized for compactness nor URL-
    safe.
 Unsecured JWS
    A JWS that provides no integrity protection.  Unsecured JWSs use
    the "alg" value "none".
 Collision-Resistant Name
    A name in a namespace that enables names to be allocated in a
    manner such that they are highly unlikely to collide with other
    names.  Examples of collision-resistant namespaces include: Domain
    Names, Object Identifiers (OIDs) as defined in the ITU-T X.660 and
    X.670 Recommendation series, and Universally Unique IDentifiers
    (UUIDs) [RFC4122].  When using an administratively delegated
    namespace, the definer of a name needs to take reasonable
    precautions to ensure they are in control of the portion of the
    namespace they use to define the name.
 StringOrURI
    A JSON string value, with the additional requirement that while
    arbitrary string values MAY be used, any value containing a ":"
    character MUST be a URI [RFC3986].  StringOrURI values are
    compared as case-sensitive strings with no transformations or
    canonicalizations applied.

Jones, et al. Standards Track [Page 6] RFC 7515 JSON Web Signature (JWS) May 2015

 The terms "JSON Web Encryption (JWE)", "JWE Compact Serialization",
 and "JWE JSON Serialization" are defined by the JWE specification
 [JWE].
 The terms "Digital Signature" and "Message Authentication Code (MAC)"
 are defined by the "Internet Security Glossary, Version 2" [RFC4949].

3. JSON Web Signature (JWS) Overview

 JWS represents digitally signed or MACed content using JSON data
 structures and base64url encoding.  These JSON data structures MAY
 contain whitespace and/or line breaks before or after any JSON values
 or structural characters, in accordance with Section 2 of RFC 7159
 [RFC7159].  A JWS represents these logical values (each of which is
 defined in Section 2):
 o  JOSE Header
 o  JWS Payload
 o  JWS Signature
 For a JWS, the JOSE Header members are the union of the members of
 these values (each of which is defined in Section 2):
 o  JWS Protected Header
 o  JWS Unprotected Header
 This document defines two serializations for JWSs: a compact, URL-
 safe serialization called the JWS Compact Serialization and a JSON
 serialization called the JWS JSON Serialization.  In both
 serializations, the JWS Protected Header, JWS Payload, and JWS
 Signature are base64url encoded, since JSON lacks a way to directly
 represent arbitrary octet sequences.

3.1. JWS Compact Serialization Overview

 In the JWS Compact Serialization, no JWS Unprotected Header is used.
 In this case, the JOSE Header and the JWS Protected Header are the
 same.
 In the JWS Compact Serialization, a JWS is represented as the
 concatenation:
    BASE64URL(UTF8(JWS Protected Header)) || '.' ||
    BASE64URL(JWS Payload) || '.' ||
    BASE64URL(JWS Signature)
 See Section 7.1 for more information about the JWS Compact
 Serialization.

Jones, et al. Standards Track [Page 7] RFC 7515 JSON Web Signature (JWS) May 2015

3.2. JWS JSON Serialization Overview

 In the JWS JSON Serialization, one or both of the JWS Protected
 Header and JWS Unprotected Header MUST be present.  In this case, the
 members of the JOSE Header are the union of the members of the JWS
 Protected Header and the JWS Unprotected Header values that are
 present.
 In the JWS JSON Serialization, a JWS is represented as a JSON object
 containing some or all of these four members:
 o  "protected", with the value BASE64URL(UTF8(JWS Protected Header))
 o  "header", with the value JWS Unprotected Header
 o  "payload", with the value BASE64URL(JWS Payload)
 o  "signature", with the value BASE64URL(JWS Signature)
 The three base64url-encoded result strings and the JWS Unprotected
 Header value are represented as members within a JSON object.  The
 inclusion of some of these values is OPTIONAL.  The JWS JSON
 Serialization can also represent multiple signature and/or MAC
 values, rather than just one.  See Section 7.2 for more information
 about the JWS JSON Serialization.

3.3. Example JWS

 This section provides an example of a JWS.  Its computation is
 described in more detail in Appendix A.1, including specifying the
 exact octet sequences representing the JSON values used and the key
 value used.
 The following example JWS Protected Header declares that the encoded
 object is a JSON Web Token [JWT] and the JWS Protected Header and the
 JWS Payload are secured using the HMAC SHA-256 [RFC2104] [SHS]
 algorithm:
   {"typ":"JWT",
    "alg":"HS256"}
 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
 The UTF-8 representation of the following JSON object is used as the
 JWS Payload.  (Note that the payload can be any content and need not
 be a representation of a JSON object.)

Jones, et al. Standards Track [Page 8] RFC 7515 JSON Web Signature (JWS) May 2015

   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}
 Encoding this JWS Payload as BASE64URL(JWS Payload) gives this value
 (with line breaks for display purposes only):
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
 Computing the HMAC of the JWS Signing Input ASCII(BASE64URL(UTF8(JWS
 Protected Header)) || '.' || BASE64URL(JWS Payload)) with the HMAC
 SHA-256 algorithm using the key specified in Appendix A.1 and
 base64url-encoding the result yields this BASE64URL(JWS Signature)
 value:
   dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
 Concatenating these values in the order Header.Payload.Signature with
 period ('.') characters between the parts yields this complete JWS
 representation using the JWS Compact Serialization (with line breaks
 for display purposes only):
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
   .
   dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
 See Appendix A for additional examples, including examples using the
 JWS JSON Serialization in Sections A.6 and A.7.

4. JOSE Header

 For a JWS, the members of the JSON object(s) representing the JOSE
 Header describe the digital signature or MAC applied to the JWS
 Protected Header and the JWS Payload and optionally additional
 properties of the JWS.  The Header Parameter names within the JOSE
 Header MUST be unique; JWS parsers MUST either reject JWSs with
 duplicate Header Parameter names or use a JSON parser that returns
 only the lexically last duplicate member name, as specified in
 Section 15.12 ("The JSON Object") of ECMAScript 5.1 [ECMAScript].
 Implementations are required to understand the specific Header
 Parameters defined by this specification that are designated as "MUST
 be understood" and process them in the manner defined in this
 specification.  All other Header Parameters defined by this

Jones, et al. Standards Track [Page 9] RFC 7515 JSON Web Signature (JWS) May 2015

 specification that are not so designated MUST be ignored when not
 understood.  Unless listed as a critical Header Parameter, per
 Section 4.1.11, all Header Parameters not defined by this
 specification MUST be ignored when not understood.
 There are three classes of Header Parameter names: Registered Header
 Parameter names, Public Header Parameter names, and Private Header
 Parameter names.

4.1. Registered Header Parameter Names

 The following Header Parameter names for use in JWSs are registered
 in the IANA "JSON Web Signature and Encryption Header Parameters"
 registry established by Section 9.1, with meanings as defined in the
 subsections below.
 As indicated by the common registry, JWSs and JWEs share a common
 Header Parameter space; when a parameter is used by both
 specifications, its usage must be compatible between the
 specifications.

4.1.1. "alg" (Algorithm) Header Parameter

 The "alg" (algorithm) Header Parameter identifies the cryptographic
 algorithm used to secure the JWS.  The JWS Signature value is not
 valid if the "alg" value does not represent a supported algorithm or
 if there is not a key for use with that algorithm associated with the
 party that digitally signed or MACed the content.  "alg" values
 should either be registered in the IANA "JSON Web Signature and
 Encryption Algorithms" registry established by [JWA] or be a value
 that contains a Collision-Resistant Name.  The "alg" value is a case-
 sensitive ASCII string containing a StringOrURI value.  This Header
 Parameter MUST be present and MUST be understood and processed by
 implementations.
 A list of defined "alg" values for this use can be found in the IANA
 "JSON Web Signature and Encryption Algorithms" registry established
 by [JWA]; the initial contents of this registry are the values
 defined in Section 3.1 of [JWA].

4.1.2. "jku" (JWK Set URL) Header Parameter

 The "jku" (JWK Set URL) Header Parameter is a URI [RFC3986] that
 refers to a resource for a set of JSON-encoded public keys, one of
 which corresponds to the key used to digitally sign the JWS.  The
 keys MUST be encoded as a JWK Set [JWK].  The protocol used to
 acquire the resource MUST provide integrity protection; an HTTP GET
 request to retrieve the JWK Set MUST use Transport Layer Security

Jones, et al. Standards Track [Page 10] RFC 7515 JSON Web Signature (JWS) May 2015

 (TLS) [RFC2818] [RFC5246]; and the identity of the server MUST be
 validated, as per Section 6 of RFC 6125 [RFC6125].  Also, see
 Section 8 on TLS requirements.  Use of this Header Parameter is
 OPTIONAL.

4.1.3. "jwk" (JSON Web Key) Header Parameter

 The "jwk" (JSON Web Key) Header Parameter is the public key that
 corresponds to the key used to digitally sign the JWS.  This key is
 represented as a JSON Web Key [JWK].  Use of this Header Parameter is
 OPTIONAL.

4.1.4. "kid" (Key ID) Header Parameter

 The "kid" (key ID) Header Parameter is a hint indicating which key
 was used to secure the JWS.  This parameter allows originators to
 explicitly signal a change of key to recipients.  The structure of
 the "kid" value is unspecified.  Its value MUST be a case-sensitive
 string.  Use of this Header Parameter is OPTIONAL.
 When used with a JWK, the "kid" value is used to match a JWK "kid"
 parameter value.

4.1.5. "x5u" (X.509 URL) Header Parameter

 The "x5u" (X.509 URL) Header Parameter is a URI [RFC3986] that refers
 to a resource for the X.509 public key certificate or certificate
 chain [RFC5280] corresponding to the key used to digitally sign the
 JWS.  The identified resource MUST provide a representation of the
 certificate or certificate chain that conforms to RFC 5280 [RFC5280]
 in PEM-encoded form, with each certificate delimited as specified in
 Section 6.1 of RFC 4945 [RFC4945].  The certificate containing the
 public key corresponding to the key used to digitally sign the JWS
 MUST be the first certificate.  This MAY be followed by additional
 certificates, with each subsequent certificate being the one used to
 certify the previous one.  The protocol used to acquire the resource
 MUST provide integrity protection; an HTTP GET request to retrieve
 the certificate MUST use TLS [RFC2818] [RFC5246]; and the identity of
 the server MUST be validated, as per Section 6 of RFC 6125 [RFC6125].
 Also, see Section 8 on TLS requirements.  Use of this Header
 Parameter is OPTIONAL.

4.1.6. "x5c" (X.509 Certificate Chain) Header Parameter

 The "x5c" (X.509 certificate chain) Header Parameter contains the
 X.509 public key certificate or certificate chain [RFC5280]
 corresponding to the key used to digitally sign the JWS.  The
 certificate or certificate chain is represented as a JSON array of

Jones, et al. Standards Track [Page 11] RFC 7515 JSON Web Signature (JWS) May 2015

 certificate value strings.  Each string in the array is a
 base64-encoded (Section 4 of [RFC4648] -- not base64url-encoded) DER
 [ITU.X690.2008] PKIX certificate value.  The certificate containing
 the public key corresponding to the key used to digitally sign the
 JWS MUST be the first certificate.  This MAY be followed by
 additional certificates, with each subsequent certificate being the
 one used to certify the previous one.  The recipient MUST validate
 the certificate chain according to RFC 5280 [RFC5280] and consider
 the certificate or certificate chain to be invalid if any validation
 failure occurs.  Use of this Header Parameter is OPTIONAL.
 See Appendix B for an example "x5c" value.

4.1.7. "x5t" (X.509 Certificate SHA-1 Thumbprint) Header Parameter

 The "x5t" (X.509 certificate SHA-1 thumbprint) Header Parameter is a
 base64url-encoded SHA-1 thumbprint (a.k.a. digest) of the DER
 encoding of the X.509 certificate [RFC5280] corresponding to the key
 used to digitally sign the JWS.  Note that certificate thumbprints
 are also sometimes known as certificate fingerprints.  Use of this
 Header Parameter is OPTIONAL.

4.1.8. "x5t#S256" (X.509 Certificate SHA-256 Thumbprint) Header

      Parameter
 The "x5t#S256" (X.509 certificate SHA-256 thumbprint) Header
 Parameter is a base64url-encoded SHA-256 thumbprint (a.k.a. digest)
 of the DER encoding of the X.509 certificate [RFC5280] corresponding
 to the key used to digitally sign the JWS.  Note that certificate
 thumbprints are also sometimes known as certificate fingerprints.
 Use of this Header Parameter is OPTIONAL.

4.1.9. "typ" (Type) Header Parameter

 The "typ" (type) Header Parameter is used by JWS applications to
 declare the media type [IANA.MediaTypes] of this complete JWS.  This
 is intended for use by the application when more than one kind of
 object could be present in an application data structure that can
 contain a JWS; the application can use this value to disambiguate
 among the different kinds of objects that might be present.  It will
 typically not be used by applications when the kind of object is
 already known.  This parameter is ignored by JWS implementations; any
 processing of this parameter is performed by the JWS application.
 Use of this Header Parameter is OPTIONAL.
 Per RFC 2045 [RFC2045], all media type values, subtype values, and
 parameter names are case insensitive.  However, parameter values are
 case sensitive unless otherwise specified for the specific parameter.

Jones, et al. Standards Track [Page 12] RFC 7515 JSON Web Signature (JWS) May 2015

 To keep messages compact in common situations, it is RECOMMENDED that
 producers omit an "application/" prefix of a media type value in a
 "typ" Header Parameter when no other '/' appears in the media type
 value.  A recipient using the media type value MUST treat it as if
 "application/" were prepended to any "typ" value not containing a
 '/'.  For instance, a "typ" value of "example" SHOULD be used to
 represent the "application/example" media type, whereas the media
 type "application/example;part="1/2"" cannot be shortened to
 "example;part="1/2"".
 The "typ" value "JOSE" can be used by applications to indicate that
 this object is a JWS or JWE using the JWS Compact Serialization or
 the JWE Compact Serialization.  The "typ" value "JOSE+JSON" can be
 used by applications to indicate that this object is a JWS or JWE
 using the JWS JSON Serialization or the JWE JSON Serialization.
 Other type values can also be used by applications.

4.1.10. "cty" (Content Type) Header Parameter

 The "cty" (content type) Header Parameter is used by JWS applications
 to declare the media type [IANA.MediaTypes] of the secured content
 (the payload).  This is intended for use by the application when more
 than one kind of object could be present in the JWS Payload; the
 application can use this value to disambiguate among the different
 kinds of objects that might be present.  It will typically not be
 used by applications when the kind of object is already known.  This
 parameter is ignored by JWS implementations; any processing of this
 parameter is performed by the JWS application.  Use of this Header
 Parameter is OPTIONAL.
 Per RFC 2045 [RFC2045], all media type values, subtype values, and
 parameter names are case insensitive.  However, parameter values are
 case sensitive unless otherwise specified for the specific parameter.
 To keep messages compact in common situations, it is RECOMMENDED that
 producers omit an "application/" prefix of a media type value in a
 "cty" Header Parameter when no other '/' appears in the media type
 value.  A recipient using the media type value MUST treat it as if
 "application/" were prepended to any "cty" value not containing a
 '/'.  For instance, a "cty" value of "example" SHOULD be used to
 represent the "application/example" media type, whereas the media
 type "application/example;part="1/2"" cannot be shortened to
 "example;part="1/2"".

Jones, et al. Standards Track [Page 13] RFC 7515 JSON Web Signature (JWS) May 2015

4.1.11. "crit" (Critical) Header Parameter

 The "crit" (critical) Header Parameter indicates that extensions to
 this specification and/or [JWA] are being used that MUST be
 understood and processed.  Its value is an array listing the Header
 Parameter names present in the JOSE Header that use those extensions.
 If any of the listed extension Header Parameters are not understood
 and supported by the recipient, then the JWS is invalid.  Producers
 MUST NOT include Header Parameter names defined by this specification
 or [JWA] for use with JWS, duplicate names, or names that do not
 occur as Header Parameter names within the JOSE Header in the "crit"
 list.  Producers MUST NOT use the empty list "[]" as the "crit"
 value.  Recipients MAY consider the JWS to be invalid if the critical
 list contains any Header Parameter names defined by this
 specification or [JWA] for use with JWS or if any other constraints
 on its use are violated.  When used, this Header Parameter MUST be
 integrity protected; therefore, it MUST occur only within the JWS
 Protected Header.  Use of this Header Parameter is OPTIONAL.  This
 Header Parameter MUST be understood and processed by implementations.
 An example use, along with a hypothetical "exp" (expiration time)
 field is:
   {"alg":"ES256",
    "crit":["exp"],
    "exp":1363284000
   }

4.2. Public Header Parameter Names

 Additional Header Parameter names can be defined by those using JWSs.
 However, in order to prevent collisions, any new Header Parameter
 name should either be registered in the IANA "JSON Web Signature and
 Encryption Header Parameters" registry established by Section 9.1 or
 be a Public Name (a value that contains a Collision-Resistant Name).
 In each case, the definer of the name or value needs to take
 reasonable precautions to make sure they are in control of the part
 of the namespace they use to define the Header Parameter name.
 New Header Parameters should be introduced sparingly, as they can
 result in non-interoperable JWSs.

4.3. Private Header Parameter Names

 A producer and consumer of a JWS may agree to use Header Parameter
 names that are Private Names (names that are not Registered Header
 Parameter names (Section 4.1)) or Public Header Parameter names

Jones, et al. Standards Track [Page 14] RFC 7515 JSON Web Signature (JWS) May 2015

 (Section 4.2).  Unlike Public Header Parameter names, Private Header
 Parameter names are subject to collision and should be used with
 caution.

5. Producing and Consuming JWSs

5.1. Message Signature or MAC Computation

 To create a JWS, the following steps are performed.  The order of the
 steps is not significant in cases where there are no dependencies
 between the inputs and outputs of the steps.
 1.  Create the content to be used as the JWS Payload.
 2.  Compute the encoded payload value BASE64URL(JWS Payload).
 3.  Create the JSON object(s) containing the desired set of Header
     Parameters, which together comprise the JOSE Header (the JWS
     Protected Header and/or the JWS Unprotected Header).
 4.  Compute the encoded header value BASE64URL(UTF8(JWS Protected
     Header)).  If the JWS Protected Header is not present (which can
     only happen when using the JWS JSON Serialization and no
     "protected" member is present), let this value be the empty
     string.
 5.  Compute the JWS Signature in the manner defined for the
     particular algorithm being used over the JWS Signing Input
     ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' ||
     BASE64URL(JWS Payload)).  The "alg" (algorithm) Header Parameter
     MUST be present in the JOSE Header, with the algorithm value
     accurately representing the algorithm used to construct the JWS
     Signature.
 6.  Compute the encoded signature value BASE64URL(JWS Signature).
 7.  If the JWS JSON Serialization is being used, repeat this process
     (steps 3-6) for each digital signature or MAC operation being
     performed.
 8.  Create the desired serialized output.  The JWS Compact
     Serialization of this result is BASE64URL(UTF8(JWS Protected
     Header)) || '.' || BASE64URL(JWS Payload) || '.' || BASE64URL(JWS
     Signature).  The JWS JSON Serialization is described in
     Section 7.2.

Jones, et al. Standards Track [Page 15] RFC 7515 JSON Web Signature (JWS) May 2015

5.2. Message Signature or MAC Validation

 When validating a JWS, the following steps are performed.  The order
 of the steps is not significant in cases where there are no
 dependencies between the inputs and outputs of the steps.  If any of
 the listed steps fails, then the signature or MAC cannot be
 validated.
 When there are multiple JWS Signature values, it is an application
 decision which of the JWS Signature values must successfully validate
 for the JWS to be accepted.  In some cases, all must successfully
 validate, or the JWS will be considered invalid.  In other cases,
 only a specific JWS Signature value needs to be successfully
 validated.  However, in all cases, at least one JWS Signature value
 MUST successfully validate, or the JWS MUST be considered invalid.
 1.  Parse the JWS representation to extract the serialized values for
     the components of the JWS.  When using the JWS Compact
     Serialization, these components are the base64url-encoded
     representations of the JWS Protected Header, the JWS Payload, and
     the JWS Signature, and when using the JWS JSON Serialization,
     these components also include the unencoded JWS Unprotected
     Header value.  When using the JWS Compact Serialization, the JWS
     Protected Header, the JWS Payload, and the JWS Signature are
     represented as base64url-encoded values in that order, with each
     value being separated from the next by a single period ('.')
     character, resulting in exactly two delimiting period characters
     being used.  The JWS JSON Serialization is described in
     Section 7.2.
 2.  Base64url-decode the encoded representation of the JWS Protected
     Header, following the restriction that no line breaks,
     whitespace, or other additional characters have been used.
 3.  Verify that the resulting octet sequence is a UTF-8-encoded
     representation of a completely valid JSON object conforming to
     RFC 7159 [RFC7159]; let the JWS Protected Header be this JSON
     object.
 4.  If using the JWS Compact Serialization, let the JOSE Header be
     the JWS Protected Header.  Otherwise, when using the JWS JSON
     Serialization, let the JOSE Header be the union of the members of
     the corresponding JWS Protected Header and JWS Unprotected
     Header, all of which must be completely valid JSON objects.
     During this step, verify that the resulting JOSE Header does not
     contain duplicate Header Parameter names.  When using the JWS

Jones, et al. Standards Track [Page 16] RFC 7515 JSON Web Signature (JWS) May 2015

     JSON Serialization, this restriction includes that the same
     Header Parameter name also MUST NOT occur in distinct JSON object
     values that together comprise the JOSE Header.
 5.  Verify that the implementation understands and can process all
     fields that it is required to support, whether required by this
     specification, by the algorithm being used, or by the "crit"
     Header Parameter value, and that the values of those parameters
     are also understood and supported.
 6.  Base64url-decode the encoded representation of the JWS Payload,
     following the restriction that no line breaks, whitespace, or
     other additional characters have been used.
 7.  Base64url-decode the encoded representation of the JWS Signature,
     following the restriction that no line breaks, whitespace, or
     other additional characters have been used.
 8.  Validate the JWS Signature against the JWS Signing Input
     ASCII(BASE64URL(UTF8(JWS Protected Header)) || '.' ||
     BASE64URL(JWS Payload)) in the manner defined for the algorithm
     being used, which MUST be accurately represented by the value of
     the "alg" (algorithm) Header Parameter, which MUST be present.
     See Section 10.6 for security considerations on algorithm
     validation.  Record whether the validation succeeded or not.
 9.  If the JWS JSON Serialization is being used, repeat this process
     (steps 4-8) for each digital signature or MAC value contained in
     the representation.
 10. If none of the validations in step 9 succeeded, then the JWS MUST
     be considered invalid.  Otherwise, in the JWS JSON Serialization
     case, return a result to the application indicating which of the
     validations succeeded and failed.  In the JWS Compact
     Serialization case, the result can simply indicate whether or not
     the JWS was successfully validated.
 Finally, note that it is an application decision which algorithms may
 be used in a given context.  Even if a JWS can be successfully
 validated, unless the algorithm(s) used in the JWS are acceptable to
 the application, it SHOULD consider the JWS to be invalid.

5.3. String Comparison Rules

 Processing a JWS inevitably requires comparing known strings to
 members and values in JSON objects.  For example, in checking what
 the algorithm is, the Unicode string "alg" will be checked against
 the member names in the JOSE Header to see if there is a matching

Jones, et al. Standards Track [Page 17] RFC 7515 JSON Web Signature (JWS) May 2015

 Header Parameter name.  The same process is then used to determine if
 the value of the "alg" Header Parameter represents a supported
 algorithm.
 The JSON rules for doing member name comparison are described in
 Section 8.3 of RFC 7159 [RFC7159].  Since the only string comparison
 operations that are performed are equality and inequality, the same
 rules can be used for comparing both member names and member values
 against known strings.
 These comparison rules MUST be used for all JSON string comparisons
 except in cases where the definition of the member explicitly calls
 out that a different comparison rule is to be used for that member
 value.  Only the "typ" and "cty" member values defined in this
 specification do not use these comparison rules.
 Some applications may include case-insensitive information in a case-
 sensitive value, such as including a DNS name as part of a "kid" (key
 ID) value.  In those cases, the application may need to define a
 convention for the canonical case to use for representing the case-
 insensitive portions, such as lowercasing them, if more than one
 party might need to produce the same value so that they can be
 compared.  (However, if all other parties consume whatever value the
 producing party emitted verbatim without attempting to compare it to
 an independently produced value, then the case used by the producer
 will not matter.)
 Also, see the JSON security considerations in Section 10.12 and the
 Unicode security considerations in Section 10.13.

6. Key Identification

 It is necessary for the recipient of a JWS to be able to determine
 the key that was employed for the digital signature or MAC operation.
 The key employed can be identified using the Header Parameter methods
 described in Section 4.1 or can be identified using methods that are
 outside the scope of this specification.  Specifically, the Header
 Parameters "jku", "jwk", "kid", "x5u", "x5c", "x5t", and "x5t#S256"
 can be used to identify the key used.  These Header Parameters MUST
 be integrity protected if the information that they convey is to be
 utilized in a trust decision; however, if the only information used
 in the trust decision is a key, these parameters need not be
 integrity protected, since changing them in a way that causes a
 different key to be used will cause the validation to fail.
 The producer SHOULD include sufficient information in the Header
 Parameters to identify the key used, unless the application uses
 another means or convention to determine the key used.  Validation of

Jones, et al. Standards Track [Page 18] RFC 7515 JSON Web Signature (JWS) May 2015

 the signature or MAC fails when the algorithm used requires a key
 (which is true of all algorithms except for "none") and the key used
 cannot be determined.
 The means of exchanging any shared symmetric keys used is outside the
 scope of this specification.
 Also, see Appendix D for notes on possible key selection algorithms.

7. Serializations

 JWSs use one of two serializations: the JWS Compact Serialization or
 the JWS JSON Serialization.  Applications using this specification
 need to specify what serialization and serialization features are
 used for that application.  For instance, applications might specify
 that only the JWS JSON Serialization is used, that only JWS JSON
 Serialization support for a single signature or MAC value is used, or
 that support for multiple signatures and/or MAC values is used.  JWS
 implementations only need to implement the features needed for the
 applications they are designed to support.

7.1. JWS Compact Serialization

 The JWS Compact Serialization represents digitally signed or MACed
 content as a compact, URL-safe string.  This string is:
    BASE64URL(UTF8(JWS Protected Header)) || '.' ||
    BASE64URL(JWS Payload) || '.' ||
    BASE64URL(JWS Signature)
 Only one signature/MAC is supported by the JWS Compact Serialization
 and it provides no syntax to represent a JWS Unprotected Header
 value.

7.2. JWS JSON Serialization

 The JWS JSON Serialization represents digitally signed or MACed
 content as a JSON object.  This representation is neither optimized
 for compactness nor URL-safe.
 Two closely related syntaxes are defined for the JWS JSON
 Serialization: a fully general syntax, with which content can be
 secured with more than one digital signature and/or MAC operation,
 and a flattened syntax, which is optimized for the single digital
 signature or MAC case.

Jones, et al. Standards Track [Page 19] RFC 7515 JSON Web Signature (JWS) May 2015

7.2.1. General JWS JSON Serialization Syntax

 The following members are defined for use in top-level JSON objects
 used for the fully general JWS JSON Serialization syntax:
 payload
    The "payload" member MUST be present and contain the value
    BASE64URL(JWS Payload).
 signatures
    The "signatures" member value MUST be an array of JSON objects.
    Each object represents a signature or MAC over the JWS Payload and
    the JWS Protected Header.
 The following members are defined for use in the JSON objects that
 are elements of the "signatures" array:
 protected
    The "protected" member MUST be present and contain the value
    BASE64URL(UTF8(JWS Protected Header)) when the JWS Protected
    Header value is non-empty; otherwise, it MUST be absent.  These
    Header Parameter values are integrity protected.
 header
    The "header" member MUST be present and contain the value JWS
    Unprotected Header when the JWS Unprotected Header value is non-
    empty; otherwise, it MUST be absent.  This value is represented as
    an unencoded JSON object, rather than as a string.  These Header
    Parameter values are not integrity protected.
 signature
    The "signature" member MUST be present and contain the value
    BASE64URL(JWS Signature).
 At least one of the "protected" and "header" members MUST be present
 for each signature/MAC computation so that an "alg" Header Parameter
 value is conveyed.
 Additional members can be present in both the JSON objects defined
 above; if not understood by implementations encountering them, they
 MUST be ignored.
 The Header Parameter values used when creating or validating
 individual signature or MAC values are the union of the two sets of
 Header Parameter values that may be present: (1) the JWS Protected
 Header represented in the "protected" member of the signature/MAC's
 array element, and (2) the JWS Unprotected Header in the "header"

Jones, et al. Standards Track [Page 20] RFC 7515 JSON Web Signature (JWS) May 2015

 member of the signature/MAC's array element.  The union of these sets
 of Header Parameters comprises the JOSE Header.  The Header Parameter
 names in the two locations MUST be disjoint.
 Each JWS Signature value is computed using the parameters of the
 corresponding JOSE Header value in the same manner as for the JWS
 Compact Serialization.  This has the desirable property that each JWS
 Signature value represented in the "signatures" array is identical to
 the value that would have been computed for the same parameter in the
 JWS Compact Serialization, provided that the JWS Protected Header
 value for that signature/MAC computation (which represents the
 integrity-protected Header Parameter values) matches that used in the
 JWS Compact Serialization.
 In summary, the syntax of a JWS using the general JWS JSON
 Serialization is as follows:
   {
    "payload":"<payload contents>",
    "signatures":[
     {"protected":"<integrity-protected header 1 contents>",
      "header":<non-integrity-protected header 1 contents>,
      "signature":"<signature 1 contents>"},
     ...
     {"protected":"<integrity-protected header N contents>",
      "header":<non-integrity-protected header N contents>,
      "signature":"<signature N contents>"}]
   }
 See Appendix A.6 for an example JWS using the general JWS JSON
 Serialization syntax.

7.2.2. Flattened JWS JSON Serialization Syntax

 The flattened JWS JSON Serialization syntax is based upon the general
 syntax but flattens it, optimizing it for the single digital
 signature/MAC case.  It flattens it by removing the "signatures"
 member and instead placing those members defined for use in the
 "signatures" array (the "protected", "header", and "signature"
 members) in the top-level JSON object (at the same level as the
 "payload" member).
 The "signatures" member MUST NOT be present when using this syntax.
 Other than this syntax difference, JWS JSON Serialization objects
 using the flattened syntax are processed identically to those using
 the general syntax.

Jones, et al. Standards Track [Page 21] RFC 7515 JSON Web Signature (JWS) May 2015

 In summary, the syntax of a JWS using the flattened JWS JSON
 Serialization is as follows:
   {
    "payload":"<payload contents>",
    "protected":"<integrity-protected header contents>",
    "header":<non-integrity-protected header contents>,
    "signature":"<signature contents>"
   }
 See Appendix A.7 for an example JWS using the flattened JWS JSON
 Serialization syntax.

8. TLS Requirements

 Implementations supporting the "jku" and/or "x5u" Header Parameters
 MUST support TLS.  Which TLS version(s) ought to be implemented will
 vary over time and depend on the widespread deployment and known
 security vulnerabilities at the time of implementation.  At the time
 of this writing, TLS version 1.2 [RFC5246] is the most recent
 version.
 To protect against information disclosure and tampering,
 confidentiality protection MUST be applied using TLS with a
 ciphersuite that provides confidentiality and integrity protection.
 See current publications by the IETF TLS working group, including RFC
 6176 [RFC6176], for guidance on the ciphersuites currently considered
 to be appropriate for use.  Also, see "Recommendations for Secure Use
 of Transport Layer Security (TLS) and Datagram Transport Layer
 Security (DTLS)" [RFC7525] for recommendations on improving the
 security of software and services using TLS.
 Whenever TLS is used, the identity of the service provider encoded in
 the TLS server certificate MUST be verified using the procedures
 described in Section 6 of RFC 6125 [RFC6125].

9. IANA Considerations

 The following registration procedure is used for all the registries
 established by this specification.
 Values are registered on a Specification Required [RFC5226] basis
 after a three-week review period on the jose-reg-review@ietf.org
 mailing list, on the advice of one or more Designated Experts.
 However, to allow for the allocation of values prior to publication,
 the Designated Experts may approve registration once they are
 satisfied that such a specification will be published.

Jones, et al. Standards Track [Page 22] RFC 7515 JSON Web Signature (JWS) May 2015

 Registration requests sent to the mailing list for review should use
 an appropriate subject (e.g., "Request to register header parameter:
 example").
 Within the review period, the Designated Experts will either approve
 or deny the registration request, communicating this decision to the
 review list and IANA.  Denials should include an explanation and, if
 applicable, suggestions as to how to make the request successful.
 Registration requests that are undetermined for a period longer than
 21 days can be brought to the IESG's attention (using the
 iesg@ietf.org mailing list) for resolution.
 Criteria that should be applied by the Designated Experts includes
 determining whether the proposed registration duplicates existing
 functionality, whether it is likely to be of general applicability or
 useful only for a single application, and whether the registration
 description is clear.
 IANA must only accept registry updates from the Designated Experts
 and should direct all requests for registration to the review mailing
 list.
 It is suggested that multiple Designated Experts be appointed who are
 able to represent the perspectives of different applications using
 this specification, in order to enable broadly informed review of
 registration decisions.  In cases where a registration decision could
 be perceived as creating a conflict of interest for a particular
 Expert, that Expert should defer to the judgment of the other
 Experts.

9.1. JSON Web Signature and Encryption Header Parameters Registry

 This specification establishes the IANA "JSON Web Signature and
 Encryption Header Parameters" registry for Header Parameter names.
 The registry records the Header Parameter name and a reference to the
 specification that defines it.  The same Header Parameter name can be
 registered multiple times, provided that the parameter usage is
 compatible between the specifications.  Different registrations of
 the same Header Parameter name will typically use different Header
 Parameter Usage Locations values.

9.1.1. Registration Template

 Header Parameter Name:
    The name requested (e.g., "kid").  Because a core goal of this
    specification is for the resulting representations to be compact,
    it is RECOMMENDED that the name be short -- not to exceed 8
    characters without a compelling reason to do so.  This name is

Jones, et al. Standards Track [Page 23] RFC 7515 JSON Web Signature (JWS) May 2015

    case sensitive.  Names may not match other registered names in a
    case-insensitive manner unless the Designated Experts state that
    there is a compelling reason to allow an exception.
 Header Parameter Description:
    Brief description of the Header Parameter (e.g., "Key ID").
 Header Parameter Usage Location(s):
    The Header Parameter usage locations, which should be one or more
    of the values "JWS" or "JWE".
 Change Controller:
    For Standards Track RFCs, list the "IESG".  For others, give the
    name of the responsible party.  Other details (e.g., postal
    address, email address, home page URI) may also be included.
 Specification Document(s):
    Reference to the document or documents that specify the parameter,
    preferably including URIs that can be used to retrieve copies of
    the documents.  An indication of the relevant sections may also be
    included but is not required.

9.1.2. Initial Registry Contents

 This section registers the Header Parameter names defined in
 Section 4.1 in this registry.
 o  Header Parameter Name: "alg"
 o  Header Parameter Description: Algorithm
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.1 of RFC 7515
 o  Header Parameter Name: "jku"
 o  Header Parameter Description: JWK Set URL
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.2 of RFC 7515
 o  Header Parameter Name: "jwk"
 o  Header Parameter Description: JSON Web Key
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.3 of RFC 7515

Jones, et al. Standards Track [Page 24] RFC 7515 JSON Web Signature (JWS) May 2015

 o  Header Parameter Name: "kid"
 o  Header Parameter Description: Key ID
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.4 of RFC 7515
 o  Header Parameter Name: "x5u"
 o  Header Parameter Description: X.509 URL
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.5 of RFC 7515
 o  Header Parameter Name: "x5c"
 o  Header Parameter Description: X.509 Certificate Chain
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.6 of RFC 7515
 o  Header Parameter Name: "x5t"
 o  Header Parameter Description: X.509 Certificate SHA-1 Thumbprint
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.7 of RFC 7515
 o  Header Parameter Name: "x5t#S256"
 o  Header Parameter Description: X.509 Certificate SHA-256 Thumbprint
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.8 of RFC 7515
 o  Header Parameter Name: "typ"
 o  Header Parameter Description: Type
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.9 of RFC 7515
 o  Header Parameter Name: "cty"
 o  Header Parameter Description: Content Type
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.10 of RFC 7515
 o  Header Parameter Name: "crit"
 o  Header Parameter Description: Critical
 o  Header Parameter Usage Location(s): JWS
 o  Change Controller: IESG
 o  Specification Document(s): Section 4.1.11 of RFC 7515

Jones, et al. Standards Track [Page 25] RFC 7515 JSON Web Signature (JWS) May 2015

9.2. Media Type Registration

9.2.1. Registry Contents

 This section registers the "application/jose" media type [RFC2046] in
 the "Media Types" registry [IANA.MediaTypes] in the manner described
 in RFC 6838 [RFC6838], which can be used to indicate that the content
 is a JWS or JWE using the JWS Compact Serialization or the JWE
 Compact Serialization.  This section also registers the "application/
 jose+json" media type in the "Media Types" registry, which can be
 used to indicate that the content is a JWS or JWE using the JWS JSON
 Serialization or the JWE JSON Serialization.
 o  Type name: application
 o  Subtype name: jose
 o  Required parameters: n/a
 o  Optional parameters: n/a
 o  Encoding considerations: 8bit; application/jose values are encoded
    as a series of base64url-encoded values (some of which may be the
    empty string), each separated from the next by a single period
    ('.') character.
 o  Security considerations: See the Security Considerations section
    of RFC 7515.
 o  Interoperability considerations: n/a
 o  Published specification: RFC 7515
 o  Applications that use this media type: OpenID Connect, Mozilla
    Persona, Salesforce, Google, Android, Windows Azure, Xbox One,
    Amazon Web Services, and numerous others that use JWTs
 o  Fragment identifier considerations: n/a
 o  Additional information:
       Magic number(s): n/a
       File extension(s): n/a
       Macintosh file type code(s): n/a
 o  Person & email address to contact for further information:
    Michael B. Jones, mbj@microsoft.com
 o  Intended usage: COMMON
 o  Restrictions on usage: none
 o  Author: Michael B. Jones, mbj@microsoft.com
 o  Change Controller: IESG
 o  Provisional registration?  No

Jones, et al. Standards Track [Page 26] RFC 7515 JSON Web Signature (JWS) May 2015

 o  Type name: application
 o  Subtype name: jose+json
 o  Required parameters: n/a
 o  Optional parameters: n/a
 o  Encoding considerations: 8bit; application/jose+json values are
    represented as a JSON Object; UTF-8 encoding SHOULD be employed
    for the JSON object.
 o  Security considerations: See the Security Considerations section
    of RFC 7515
 o  Interoperability considerations: n/a
 o  Published specification: RFC 7515
 o  Applications that use this media type: Nimbus JOSE + JWT library
 o  Fragment identifier considerations: n/a
 o  Additional information:
       Magic number(s): n/a
       File extension(s): n/a
       Macintosh file type code(s): n/a
 o  Person & email address to contact for further information:
    Michael B. Jones, mbj@microsoft.com
 o  Intended usage: COMMON
 o  Restrictions on usage: none
 o  Author: Michael B. Jones, mbj@microsoft.com
 o  Change Controller: IESG
 o  Provisional registration?  No

10. Security Considerations

 All of the security issues that are pertinent to any cryptographic
 application must be addressed by JWS/JWE/JWK agents.  Among these
 issues are protecting the user's asymmetric private and symmetric
 secret keys and employing countermeasures to various attacks.
 All the security considerations in "XML Signature Syntax and
 Processing Version 2.0" [W3C.NOTE-xmldsig-core2-20130411], also apply
 to this specification, other than those that are XML specific.
 Likewise, many of the best practices documented in "XML Signature
 Best Practices" [W3C.NOTE-xmldsig-bestpractices-20130411] also apply
 to this specification, other than those that are XML specific.

10.1. Key Entropy and Random Values

 Keys are only as strong as the amount of entropy used to generate
 them.  A minimum of 128 bits of entropy should be used for all keys,
 and depending upon the application context, more may be required.

Jones, et al. Standards Track [Page 27] RFC 7515 JSON Web Signature (JWS) May 2015

 Implementations must randomly generate public/private key pairs, MAC
 keys, and padding values.  The use of inadequate pseudorandom number
 generators (PRNGs) to generate cryptographic keys can result in
 little or no security.  An attacker may find it much easier to
 reproduce the PRNG environment that produced the keys, searching the
 resulting small set of possibilities rather than brute-force
 searching the whole key space.  The generation of quality random
 numbers is difficult.  RFC 4086 [RFC4086] offers important guidance
 in this area.

10.2. Key Protection

 Implementations must protect the signer's private key.  Compromise of
 the signer's private key permits an attacker to masquerade as the
 signer.
 Implementations must protect the MAC key.  Compromise of the MAC key
 may result in undetectable modification of the authenticated content.

10.3. Key Origin Authentication

 The key management technique employed to obtain public keys must
 authenticate the origin of the key; otherwise, it is unknown what
 party signed the message.
 Likewise, the key management technique employed to distribute MAC
 keys must provide data origin authentication; otherwise, the contents
 are delivered with integrity from an unknown source.

10.4. Cryptographic Agility

 See Section 8.1 of [JWA] for security considerations on cryptographic
 agility.

10.5. Differences between Digital Signatures and MACs

 While MACs and digital signatures can both be used for integrity
 checking, there are some significant differences between the security
 properties that each of them provides.  These need to be taken into
 consideration when designing protocols and selecting the algorithms
 to be used in protocols.
 Both signatures and MACs provide for integrity checking -- verifying
 that the message has not been modified since the integrity value was
 computed.  However, MACs provide for origination identification only
 under specific circumstances.  It can normally be assumed that a
 private key used for a signature is only in the hands of a single
 entity (although perhaps a distributed entity, in the case of

Jones, et al. Standards Track [Page 28] RFC 7515 JSON Web Signature (JWS) May 2015

 replicated servers); however, a MAC key needs to be in the hands of
 all the entities that use it for integrity computation and checking.
 Validation of a MAC only provides corroboration that the message was
 generated by one of the parties that knows the symmetric MAC key.
 This means that origination can only be determined if a MAC key is
 known only to two entities and the recipient knows that it did not
 create the message.  MAC validation cannot be used to prove
 origination to a third party.

10.6. Algorithm Validation

 The digital signature representations for some algorithms include
 information about the algorithm used inside the signature value.  For
 instance, signatures produced with RSASSA-PKCS1-v1_5 [RFC3447] encode
 the hash function used, and many libraries actually use the hash
 algorithm specified inside the signature when validating the
 signature.  When using such libraries, as part of the algorithm
 validation performed, implementations MUST ensure that the algorithm
 information encoded in the signature corresponds to that specified
 with the "alg" Header Parameter.  If this is not done, an attacker
 could claim to have used a strong hash algorithm while actually using
 a weak one represented in the signature value.

10.7. Algorithm Protection

 In some usages of JWS, there is a risk of algorithm substitution
 attacks, in which an attacker can use an existing digital signature
 value with a different signature algorithm to make it appear that a
 signer has signed something that it has not.  These attacks have been
 discussed in detail in the context of Cryptographic Message Syntax
 (CMS) [RFC6211].  This risk arises when all of the following are
 true:
 o  Verifiers of a signature support multiple algorithms.
 o  Given an existing signature, an attacker can find another payload
    that produces the same signature value with a different algorithm.
 o  The payload crafted by the attacker is valid in the application
    context.
 There are several ways for an application to mitigate algorithm
 substitution attacks:
 o  Use only digital signature algorithms that are not vulnerable to
    substitution attacks.  Substitution attacks are only feasible if
    an attacker can compute pre-images for a hash function accepted by

Jones, et al. Standards Track [Page 29] RFC 7515 JSON Web Signature (JWS) May 2015

    the recipient.  All JWA-defined signature algorithms use SHA-2
    hashes, for which there are no known pre-image attacks, as of the
    time of this writing.
 o  Require that the "alg" Header Parameter be carried in the JWS
    Protected Header.  (This is always the case when using the JWS
    Compact Serialization and is the approach taken by CMS [RFC6211].)
 o  Include a field containing the algorithm in the application
    payload, and require that it be matched with the "alg" Header
    Parameter during verification.  (This is the approach taken by
    PKIX [RFC5280].)

10.8. Chosen Plaintext Attacks

 Creators of JWSs should not allow third parties to insert arbitrary
 content into the message without adding entropy not controlled by the
 third party.

10.9. Timing Attacks

 When cryptographic algorithms are implemented in such a way that
 successful operations take a different amount of time than
 unsuccessful operations, attackers may be able to use the time
 difference to obtain information about the keys employed.  Therefore,
 such timing differences must be avoided.

10.10. Replay Protection

 While not directly in scope for this specification, note that
 applications using JWS (or JWE) objects can thwart replay attacks by
 including a unique message identifier as integrity-protected content
 in the JWS (or JWE) message and having the recipient verify that the
 message has not been previously received or acted upon.

10.11. SHA-1 Certificate Thumbprints

 A SHA-1 hash is used when computing "x5t" (X.509 certificate SHA-1
 thumbprint) values, for compatibility reasons.  Should an effective
 means of producing SHA-1 hash collisions be developed and should an
 attacker wish to interfere with the use of a known certificate on a
 given system, this could be accomplished by creating another
 certificate whose SHA-1 hash value is the same and adding it to the
 certificate store used by the intended victim.  A prerequisite to
 this attack succeeding is the attacker having write access to the
 intended victim's certificate store.

Jones, et al. Standards Track [Page 30] RFC 7515 JSON Web Signature (JWS) May 2015

 Alternatively, the "x5t#S256" (X.509 certificate SHA-256 thumbprint)
 Header Parameter could be used instead of "x5t".  However, at the
 time of this writing, no development platform is known to support
 SHA-256 certificate thumbprints.

10.12. JSON Security Considerations

 Strict JSON [RFC7159] validation is a security requirement.  If
 malformed JSON is received, then the intent of the producer is
 impossible to reliably discern.  Ambiguous and potentially
 exploitable situations could arise if the JSON parser used does not
 reject malformed JSON syntax.  In particular, any JSON inputs not
 conforming to the JSON-text syntax defined in RFC 7159 MUST be
 rejected in their entirety by JSON parsers.
 Section 4 of "The JavaScript Object Notation (JSON) Data Interchange
 Format" [RFC7159] states, "The names within an object SHOULD be
 unique", whereas this specification states that
    The Header Parameter names within the JOSE Header MUST be unique;
    JWS parsers MUST either reject JWSs with duplicate Header
    Parameter names or use a JSON parser that returns only the
    lexically last duplicate member name, as specified in
    Section 15.12 ("The JSON Object") of ECMAScript 5.1 [ECMAScript].
 Thus, this specification requires that the "SHOULD" in Section 4 of
 [RFC7159] be treated as a "MUST" by producers and that it be either
 treated as a "MUST" or treated in the manner specified in ECMAScript
 5.1 by consumers.  Ambiguous and potentially exploitable situations
 could arise if the JSON parser used does not enforce the uniqueness
 of member names or returns an unpredictable value for duplicate
 member names.
 Some JSON parsers might not reject input that contains extra
 significant characters after a valid input.  For instance, the input
 "{"tag":"value"}ABCD" contains a valid JSON-text object followed by
 the extra characters "ABCD".  Implementations MUST consider JWSs
 containing such input to be invalid.

10.13. Unicode Comparison Security Considerations

 Header Parameter names and algorithm names are Unicode strings.  For
 security reasons, the representations of these names must be compared
 verbatim after performing any escape processing (as per Section 8.3
 of RFC 7159 [RFC7159]).  This means, for instance, that these JSON
 strings must compare as being equal ("sig", "\u0073ig"), whereas
 these must all compare as being not equal to the first set or to each
 other ("SIG", "Sig", "si\u0047").

Jones, et al. Standards Track [Page 31] RFC 7515 JSON Web Signature (JWS) May 2015

 JSON strings can contain characters outside the Unicode Basic
 Multilingual Plane.  For instance, the G clef character (U+1D11E) may
 be represented in a JSON string as "\uD834\uDD1E".  Ideally, JWS
 implementations SHOULD ensure that characters outside the Basic
 Multilingual Plane are preserved and compared correctly;
 alternatively, if this is not possible due to these characters
 exercising limitations present in the underlying JSON implementation,
 then input containing them MUST be rejected.

11. References

11.1. Normative References

 [ECMAScript] Ecma International, "ECMAScript Language Specification,
              5.1 Edition", ECMA 262, June 2011,
              <http://www.ecma-international.org/ecma-262/5.1/
              ECMA-262.pdf>.
 [IANA.MediaTypes]
              IANA, "Media Types",
              <http://www.iana.org/assignments/media-types>.
 [ITU.X690.2008]
              International Telecommunications Union, "Information
              Technology - ASN.1 encoding rules: Specification of
              Basic Encoding Rules (BER), Canonical Encoding Rules
              (CER) and Distinguished Encoding Rules (DER)", ITU-T
              Recommendation X.690, 2008.
 [JWA]        Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
              DOI 10.17487/RFC7518, May 2015,
              <http://www.rfc-editor.org/info/rfc7518>.
 [JWK]        Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,
              <http://www.rfc-editor.org/info/rfc7517>.
 [RFC20]      Cerf, V., "ASCII format for Network Interchange",
              STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969,
              <http://www.rfc-editor.org/info/rfc20>.
 [RFC2045]    Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part One: Format of Internet Message
              Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
              <http://www.rfc-editor.org/info/rfc2045>.

Jones, et al. Standards Track [Page 32] RFC 7515 JSON Web Signature (JWS) May 2015

 [RFC2046]    Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              DOI 10.17487/RFC2046, November 1996,
              <http://www.rfc-editor.org/info/rfc2046>.
 [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.
 [RFC2818]    Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000,
              <http://www.rfc-editor.org/info/rfc2818>.
 [RFC3629]    Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <http://www.rfc-editor.org/info/rfc3629>.
 [RFC3986]    Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <http://www.rfc-editor.org/info/rfc3986>.
 [RFC4648]    Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October
              2006, <http://www.rfc-editor.org/info/rfc4648>.
 [RFC4945]    Korver, B., "The Internet IP Security PKI Profile of
              IKEv1/ISAKMP, IKEv2, and PKIX", RFC 4945,
              DOI 10.17487/RFC4945, August 2007,
              <http://www.rfc-editor.org/info/rfc4945>.
 [RFC4949]    Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <http://www.rfc-editor.org/info/rfc4949>.
 [RFC5246]    Dierks, T. and E. Rescorla, "The Transport Layer
              Security (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <http://www.rfc-editor.org/info/rfc5246>.
 [RFC5280]    Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation
              List (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May
              2008, <http://www.rfc-editor.org/info/rfc5280>.

Jones, et al. Standards Track [Page 33] RFC 7515 JSON Web Signature (JWS) May 2015

 [RFC6125]    Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service
              Identity within Internet Public Key Infrastructure Using
              X.509 (PKIX) Certificates in the Context of Transport
              Layer Security (TLS)", RFC 6125, DOI 10.17487/RFC6125,
              March 2011, <http://www.rfc-editor.org/info/rfc6125>.
 [RFC6176]    Turner, S. and T. Polk, "Prohibiting Secure Sockets
              Layer (SSL) Version 2.0", RFC 6176,
              DOI 10.17487/RFC6176, March 2011,
              <http://www.rfc-editor.org/info/rfc6176>.
 [RFC7159]    Bray, T., Ed., "The JavaScript Object Notation (JSON)
              Data Interchange Format", RFC 7159,
              DOI 10.17487/RFC7159, March 2014,
              <http://www.rfc-editor.org/info/rfc7159>.
 [UNICODE]    The Unicode Consortium, "The Unicode Standard",
              <http://www.unicode.org/versions/latest/>.

11.2. Informative References

 [CanvasApp]  Facebook, "Canvas Applications",
              <http://developers.facebook.com/docs/authentication/
              canvas>.
 [JSS]        Bradley, J. and N. Sakimura, Ed., "JSON Simple Sign",
              September 2010, <http://jsonenc.info/jss/1.0/>.
 [JWE]        Jones, M. and J. Hildebrand, "JSON Web Encryption
              (JWE)", RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <http://www.rfc-editor.org/info/rfc7516>.
 [JWT]        Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <http://www.rfc-editor.org/info/rfc7519>.
 [MagicSignatures]
              Panzer, J., Ed., Laurie, B., and D. Balfanz, "Magic
              Signatures", January 2011,
              <http://salmon-protocol.googlecode.com/svn/trunk/
              draft-panzer-magicsig-01.html>.
 [RFC2104]    Krawczyk, H., Bellare, M., and R. Canetti, "HMAC:
              Keyed-Hashing for Message Authentication", RFC 2104,
              DOI 10.17487/RFC2104, February 1997,
              <http://www.rfc-editor.org/info/rfc2104>.

Jones, et al. Standards Track [Page 34] RFC 7515 JSON Web Signature (JWS) May 2015

 [RFC3447]    Jonsson, J. and B. Kaliski, "Public-Key Cryptography
              Standards (PKCS) #1: RSA Cryptography Specifications
              Version 2.1", RFC 3447, DOI 10.17487/RFC3447, February
              2003, <http://www.rfc-editor.org/info/rfc3447>.
 [RFC4086]    Eastlake 3rd, D., Schiller, J., and S. Crocker,
              "Randomness Requirements for Security", BCP 106,
              RFC 4086, DOI 10.17487/RFC4086, June 2005,
              <http://www.rfc-editor.org/info/rfc4086>.
 [RFC4122]    Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <http://www.rfc-editor.org/info/rfc4122>.
 [RFC5226]    Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.
 [RFC6211]    Schaad, J., "Cryptographic Message Syntax (CMS)
              Algorithm Identifier Protection Attribute", RFC 6211,
              DOI 10.17487/RFC6211, April 2011,
              <http://www.rfc-editor.org/info/rfc6211>.
 [RFC6838]    Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <http://www.rfc-editor.org/info/rfc6838>.
 [RFC7525]    Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <http://www.rfc-editor.org/info/rfc7525>.
 [SHS]        National Institute of Standards and Technology, "Secure
              Hash Standard (SHS)", FIPS PUB 180-4, March 2012,
              <http://csrc.nist.gov/publications/fips/fips180-4/
              fips-180-4.pdf>.
 [W3C.NOTE-xmldsig-bestpractices-20130411]
              Hirsch, F. and P. Datta, "XML Signature Best Practices",
              World Wide Web Consortium Note
              NOTE-xmldsig-bestpractices-20130411, April 2013,
              <http://www.w3.org/TR/2013/
              NOTE-xmldsig-bestpractices-20130411/>.

Jones, et al. Standards Track [Page 35] RFC 7515 JSON Web Signature (JWS) May 2015

 [W3C.NOTE-xmldsig-core2-20130411]
              Eastlake, D., Reagle, J., Solo, D., Hirsch, F.,
              Roessler, T., Yiu, K., Datta, P., and S. Cantor, "XML
              Signature Syntax and Processing Version 2.0", World Wide
              Web Consortium Note NOTE-xmldsig-core2-20130411, April
              2013,
              <http://www.w3.org/TR/2013/NOTE-xmldsig-core2-20130411/>.

Jones, et al. Standards Track [Page 36] RFC 7515 JSON Web Signature (JWS) May 2015

Appendix A. JWS Examples

 This section provides several examples of JWSs.  While the first
 three examples all represent JSON Web Tokens (JWTs) [JWT], the
 payload can be any octet sequence, as shown in Appendix A.4.

A.1. Example JWS Using HMAC SHA-256

A.1.1. Encoding

 The following example JWS Protected Header declares that the data
 structure is a JWT [JWT] and the JWS Signing Input is secured using
 the HMAC SHA-256 algorithm.
   {"typ":"JWT",
    "alg":"HS256"}
 To remove potential ambiguities in the representation of the JSON
 object above, the actual octet sequence representing UTF8(JWS
 Protected Header) used in this example is also included below.  (Note
 that ambiguities can arise due to differing platform representations
 of line breaks (CRLF versus LF), differing spacing at the beginning
 and ends of lines, whether the last line has a terminating line break
 or not, and other causes.  In the representation used in this
 example, the first line has no leading or trailing spaces, a CRLF
 line break (13, 10) occurs between the first and second lines, the
 second line has one leading space (32) and no trailing spaces, and
 the last line does not have a terminating line break.)  The octets
 representing UTF8(JWS Protected Header) in this example (using JSON
 array notation) are:
 [123, 34, 116, 121, 112, 34, 58, 34, 74, 87, 84, 34, 44, 13, 10, 32,
 34, 97, 108, 103, 34, 58, 34, 72, 83, 50, 53, 54, 34, 125]
 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
 The JWS Payload used in this example is the octets of the UTF-8
 representation of the JSON object below.  (Note that the payload can
 be any base64url-encoded octet sequence and need not be a base64url-
 encoded JSON object.)
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}

Jones, et al. Standards Track [Page 37] RFC 7515 JSON Web Signature (JWS) May 2015

 The following octet sequence, which is the UTF-8 representation used
 in this example for the JSON object above, is the JWS Payload:
 [123, 34, 105, 115, 115, 34, 58, 34, 106, 111, 101, 34, 44, 13, 10,
 32, 34, 101, 120, 112, 34, 58, 49, 51, 48, 48, 56, 49, 57, 51, 56,
 48, 44, 13, 10, 32, 34, 104, 116, 116, 112, 58, 47, 47, 101, 120, 97,
 109, 112, 108, 101, 46, 99, 111, 109, 47, 105, 115, 95, 114, 111,
 111, 116, 34, 58, 116, 114, 117, 101, 125]
 Encoding this JWS Payload as BASE64URL(UTF8(JWS Payload)) gives this
 value (with line breaks for display purposes only):
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
 Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' ||
 BASE64URL(JWS Payload) gives this string (with line breaks for
 display purposes only):
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
 The resulting JWS Signing Input value, which is the ASCII
 representation of above string, is the following octet sequence
 (using JSON array notation):
 [101, 121, 74, 48, 101, 88, 65, 105, 79, 105, 74, 75, 86, 49, 81,
 105, 76, 65, 48, 75, 73, 67, 74, 104, 98, 71, 99, 105, 79, 105, 74,
 73, 85, 122, 73, 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51,
 77, 105, 79, 105, 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67,
 74, 108, 101, 72, 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84,
 107, 122, 79, 68, 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100,
 72, 65, 54, 76, 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76,
 109, 78, 118, 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73,
 106, 112, 48, 99, 110, 86, 108, 102, 81]
 HMACs are generated using keys.  This example uses the symmetric key
 represented in JSON Web Key [JWK] format below (with line breaks
 within values for display purposes only):
   {"kty":"oct",
    "k":"AyM1SysPpbyDfgZld3umj1qzKObwVMkoqQ-EstJQLr_T-1qS0gZH75
         aKtMN3Yj0iPS4hcgUuTwjAzZr1Z9CAow"
   }

Jones, et al. Standards Track [Page 38] RFC 7515 JSON Web Signature (JWS) May 2015

 Running the HMAC SHA-256 algorithm on the JWS Signing Input with this
 key yields this JWS Signature octet sequence:
 [116, 24, 223, 180, 151, 153, 224, 37, 79, 250, 96, 125, 216, 173,
 187, 186, 22, 212, 37, 77, 105, 214, 191, 240, 91, 88, 5, 88, 83,
 132, 141, 121]
 Encoding this JWS Signature as BASE64URL(JWS Signature) gives this
 value:
   dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
 Concatenating these values in the order Header.Payload.Signature with
 period ('.') characters between the parts yields this complete JWS
 representation using the JWS Compact Serialization (with line breaks
 for display purposes only):
   eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
   .
   dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk

A.1.2. Validating

 Since the "alg" Header Parameter is "HS256", we validate the HMAC
 SHA-256 value contained in the JWS Signature.
 To validate the HMAC value, we repeat the previous process of using
 the correct key and the JWS Signing Input (which is the initial
 substring of the JWS Compact Serialization representation up until
 but not including the second period character) as input to the HMAC
 SHA-256 function and then taking the output and determining if it
 matches the JWS Signature (which is base64url decoded from the value
 encoded in the JWS representation).  If it matches exactly, the HMAC
 has been validated.

A.2. Example JWS Using RSASSA-PKCS1-v1_5 SHA-256

A.2.1. Encoding

 The JWS Protected Header in this example is different from the
 previous example in two ways.  First, because a different algorithm
 is being used, the "alg" value is different.  Second, for
 illustration purposes only, the optional "typ" (type) Header
 Parameter is not used.  (This difference is not related to the
 algorithm employed.)  The JWS Protected Header used is:

Jones, et al. Standards Track [Page 39] RFC 7515 JSON Web Signature (JWS) May 2015

   {"alg":"RS256"}
 The octets representing UTF8(JWS Protected Header) in this example
 (using JSON array notation) are:
 [123, 34, 97, 108, 103, 34, 58, 34, 82, 83, 50, 53, 54, 34, 125]
 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJhbGciOiJSUzI1NiJ9
 The JWS Payload used in this example, which follows, is the same as
 in the previous example.  Since the BASE64URL(JWS Payload) value will
 therefore be the same, its computation is not repeated here.
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}
 Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' ||
 BASE64URL(JWS Payload) gives this string (with line breaks for
 display purposes only):
   eyJhbGciOiJSUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
 The resulting JWS Signing Input value, which is the ASCII
 representation of above string, is the following octet sequence:
 [101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 83, 85, 122, 73,
 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105,
 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72,
 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68,
 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76,
 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118,
 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48,
 99, 110, 86, 108, 102, 81]

Jones, et al. Standards Track [Page 40] RFC 7515 JSON Web Signature (JWS) May 2015

 This example uses the RSA key represented in JSON Web Key [JWK]
 format below (with line breaks within values for display purposes
 only):
   {"kty":"RSA",
    "n":"ofgWCuLjybRlzo0tZWJjNiuSfb4p4fAkd_wWJcyQoTbji9k0l8W26mPddx
         HmfHQp-Vaw-4qPCJrcS2mJPMEzP1Pt0Bm4d4QlL-yRT-SFd2lZS-pCgNMs
         D1W_YpRPEwOWvG6b32690r2jZ47soMZo9wGzjb_7OMg0LOL-bSf63kpaSH
         SXndS5z5rexMdbBYUsLA9e-KXBdQOS-UTo7WTBEMa2R2CapHg665xsmtdV
         MTBQY4uDZlxvb3qCo5ZwKh9kG4LT6_I5IhlJH7aGhyxXFvUK-DWNmoudF8
         NAco9_h9iaGNj8q2ethFkMLs91kzk2PAcDTW9gb54h4FRWyuXpoQ",
    "e":"AQAB",
    "d":"Eq5xpGnNCivDflJsRQBXHx1hdR1k6Ulwe2JZD50LpXyWPEAeP88vLNO97I
         jlA7_GQ5sLKMgvfTeXZx9SE-7YwVol2NXOoAJe46sui395IW_GO-pWJ1O0
         BkTGoVEn2bKVRUCgu-GjBVaYLU6f3l9kJfFNS3E0QbVdxzubSu3Mkqzjkn
         439X0M_V51gfpRLI9JYanrC4D4qAdGcopV_0ZHHzQlBjudU2QvXt4ehNYT
         CBr6XCLQUShb1juUO1ZdiYoFaFQT5Tw8bGUl_x_jTj3ccPDVZFD9pIuhLh
         BOneufuBiB4cS98l2SR_RQyGWSeWjnczT0QU91p1DhOVRuOopznQ",
    "p":"4BzEEOtIpmVdVEZNCqS7baC4crd0pqnRH_5IB3jw3bcxGn6QLvnEtfdUdi
         YrqBdss1l58BQ3KhooKeQTa9AB0Hw_Py5PJdTJNPY8cQn7ouZ2KKDcmnPG
         BY5t7yLc1QlQ5xHdwW1VhvKn-nXqhJTBgIPgtldC-KDV5z-y2XDwGUc",
    "q":"uQPEfgmVtjL0Uyyx88GZFF1fOunH3-7cepKmtH4pxhtCoHqpWmT8YAmZxa
         ewHgHAjLYsp1ZSe7zFYHj7C6ul7TjeLQeZD_YwD66t62wDmpe_HlB-TnBA
         -njbglfIsRLtXlnDzQkv5dTltRJ11BKBBypeeF6689rjcJIDEz9RWdc",
    "dp":"BwKfV3Akq5_MFZDFZCnW-wzl-CCo83WoZvnLQwCTeDv8uzluRSnm71I3Q
         CLdhrqE2e9YkxvuxdBfpT_PI7Yz-FOKnu1R6HsJeDCjn12Sk3vmAktV2zb
         34MCdy7cpdTh_YVr7tss2u6vneTwrA86rZtu5Mbr1C1XsmvkxHQAdYo0",
    "dq":"h_96-mK1R_7glhsum81dZxjTnYynPbZpHziZjeeHcXYsXaaMwkOlODsWa
         7I9xXDoRwbKgB719rrmI2oKr6N3Do9U0ajaHF-NKJnwgjMd2w9cjz3_-ky
         NlxAr2v4IKhGNpmM5iIgOS1VZnOZ68m6_pbLBSp3nssTdlqvd0tIiTHU",
    "qi":"IYd7DHOhrWvxkwPQsRM2tOgrjbcrfvtQJipd-DlcxyVuuM9sQLdgjVk2o
         y26F0EmpScGLq2MowX7fhd_QJQ3ydy5cY7YIBi87w93IKLEdfnbJtoOPLU
         W0ITrJReOgo1cq9SbsxYawBgfp_gh6A5603k2-ZQwVK0JKSHuLFkuQ3U"
   }

Jones, et al. Standards Track [Page 41] RFC 7515 JSON Web Signature (JWS) May 2015

 The RSA private key is then passed to the RSA signing function, which
 also takes the hash type, SHA-256, and the JWS Signing Input as
 inputs.  The result of the digital signature is an octet sequence,
 which represents a big-endian integer.  In this example, it is:
 [112, 46, 33, 137, 67, 232, 143, 209, 30, 181, 216, 45, 191, 120, 69,
 243, 65, 6, 174, 27, 129, 255, 247, 115, 17, 22, 173, 209, 113, 125,
 131, 101, 109, 66, 10, 253, 60, 150, 238, 221, 115, 162, 102, 62, 81,
 102, 104, 123, 0, 11, 135, 34, 110, 1, 135, 237, 16, 115, 249, 69,
 229, 130, 173, 252, 239, 22, 216, 90, 121, 142, 232, 198, 109, 219,
 61, 184, 151, 91, 23, 208, 148, 2, 190, 237, 213, 217, 217, 112, 7,
 16, 141, 178, 129, 96, 213, 248, 4, 12, 167, 68, 87, 98, 184, 31,
 190, 127, 249, 217, 46, 10, 231, 111, 36, 242, 91, 51, 187, 230, 244,
 74, 230, 30, 177, 4, 10, 203, 32, 4, 77, 62, 249, 18, 142, 212, 1,
 48, 121, 91, 212, 189, 59, 65, 238, 202, 208, 102, 171, 101, 25, 129,
 253, 228, 141, 247, 127, 55, 45, 195, 139, 159, 175, 221, 59, 239,
 177, 139, 93, 163, 204, 60, 46, 176, 47, 158, 58, 65, 214, 18, 202,
 173, 21, 145, 18, 115, 160, 95, 35, 185, 232, 56, 250, 175, 132, 157,
 105, 132, 41, 239, 90, 30, 136, 121, 130, 54, 195, 212, 14, 96, 69,
 34, 165, 68, 200, 242, 122, 122, 45, 184, 6, 99, 209, 108, 247, 202,
 234, 86, 222, 64, 92, 178, 33, 90, 69, 178, 194, 85, 102, 181, 90,
 193, 167, 72, 160, 112, 223, 200, 163, 42, 70, 149, 67, 208, 25, 238,
 251, 71]
 Encoding the signature as BASE64URL(JWS Signature) produces this
 value (with line breaks for display purposes only):
   cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7
   AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4
   BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K
   0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv
   hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB
   p0igcN_IoypGlUPQGe77Rw

Jones, et al. Standards Track [Page 42] RFC 7515 JSON Web Signature (JWS) May 2015

 Concatenating these values in the order Header.Payload.Signature with
 period ('.') characters between the parts yields this complete JWS
 representation using the JWS Compact Serialization (with line breaks
 for display purposes only):
   eyJhbGciOiJSUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
   .
   cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZmh7
   AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjbKBYNX4
   BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHlb1L07Qe7K
   0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZESc6BfI7noOPqv
   hJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AXLIhWkWywlVmtVrB
   p0igcN_IoypGlUPQGe77Rw

A.2.2. Validating

 Since the "alg" Header Parameter is "RS256", we validate the RSASSA-
 PKCS1-v1_5 SHA-256 digital signature contained in the JWS Signature.
 Validating the JWS Signature is a bit different from the previous
 example.  We pass the public key (n, e), the JWS Signature (which is
 base64url decoded from the value encoded in the JWS representation),
 and the JWS Signing Input (which is the initial substring of the JWS
 Compact Serialization representation up until but not including the
 second period character) to an RSASSA-PKCS1-v1_5 signature verifier
 that has been configured to use the SHA-256 hash function.

A.3. Example JWS Using ECDSA P-256 SHA-256

A.3.1. Encoding

 The JWS Protected Header for this example differs from the previous
 example because a different algorithm is being used.  The JWS
 Protected Header used is:
   {"alg":"ES256"}
 The octets representing UTF8(JWS Protected Header) in this example
 (using JSON array notation) are:
 [123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 50, 53, 54, 34, 125]

Jones, et al. Standards Track [Page 43] RFC 7515 JSON Web Signature (JWS) May 2015

 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJhbGciOiJFUzI1NiJ9
 The JWS Payload used in this example, which follows, is the same as
 in the previous examples.  Since the BASE64URL(JWS Payload) value
 will therefore be the same, its computation is not repeated here.
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}
 Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' ||
 BASE64URL(JWS Payload) gives this string (with line breaks for
 display purposes only):
   eyJhbGciOiJFUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
 The resulting JWS Signing Input value, which is the ASCII
 representation of above string, is the following octet sequence:
 [101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 73,
 49, 78, 105, 74, 57, 46, 101, 121, 74, 112, 99, 51, 77, 105, 79, 105,
 74, 113, 98, 50, 85, 105, 76, 65, 48, 75, 73, 67, 74, 108, 101, 72,
 65, 105, 79, 106, 69, 122, 77, 68, 65, 52, 77, 84, 107, 122, 79, 68,
 65, 115, 68, 81, 111, 103, 73, 109, 104, 48, 100, 72, 65, 54, 76,
 121, 57, 108, 101, 71, 70, 116, 99, 71, 120, 108, 76, 109, 78, 118,
 98, 83, 57, 112, 99, 49, 57, 121, 98, 50, 57, 48, 73, 106, 112, 48,
 99, 110, 86, 108, 102, 81]
 This example uses the Elliptic Curve key represented in JSON Web Key
 [JWK] format below:
   {"kty":"EC",
    "crv":"P-256",
    "x":"f83OJ3D2xF1Bg8vub9tLe1gHMzV76e8Tus9uPHvRVEU",
    "y":"x_FEzRu9m36HLN_tue659LNpXW6pCyStikYjKIWI5a0",
    "d":"jpsQnnGQmL-YBIffH1136cspYG6-0iY7X1fCE9-E9LI"
   }
 The Elliptic Curve Digital Signature Algorithm (ECDSA) private part d
 is then passed to an ECDSA signing function, which also takes the
 curve type, P-256, the hash type, SHA-256, and the JWS Signing Input
 as inputs.  The result of the digital signature is the Elliptic Curve

Jones, et al. Standards Track [Page 44] RFC 7515 JSON Web Signature (JWS) May 2015

 (EC) point (R, S), where R and S are unsigned integers.  In this
 example, the R and S values, given as octet sequences representing
 big-endian integers are:
 +--------+----------------------------------------------------------+
 | Result | Value                                                    |
 | Name   |                                                          |
 +--------+----------------------------------------------------------+
 | R      | [14, 209, 33, 83, 121, 99, 108, 72, 60, 47, 127, 21, 88, |
 |        | 7, 212, 2, 163, 178, 40, 3, 58, 249, 124, 126, 23, 129,  |
 |        | 154, 195, 22, 158, 166, 101]                             |
 | S      | [197, 10, 7, 211, 140, 60, 112, 229, 216, 241, 45, 175,  |
 |        | 8, 74, 84, 128, 166, 101, 144, 197, 242, 147, 80, 154,   |
 |        | 143, 63, 127, 138, 131, 163, 84, 213]                    |
 +--------+----------------------------------------------------------+
 The JWS Signature is the value R || S.  Encoding the signature as
 BASE64URL(JWS Signature) produces this value (with line breaks for
 display purposes only):
   DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA
   pmWQxfKTUJqPP3-Kg6NU1Q
 Concatenating these values in the order Header.Payload.Signature with
 period ('.') characters between the parts yields this complete JWS
 representation using the JWS Compact Serialization (with line breaks
 for display purposes only):
   eyJhbGciOiJFUzI1NiJ9
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
   .
   DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8ISlSA
   pmWQxfKTUJqPP3-Kg6NU1Q

A.3.2. Validating

 Since the "alg" Header Parameter is "ES256", we validate the ECDSA
 P-256 SHA-256 digital signature contained in the JWS Signature.
 Validating the JWS Signature is a bit different from the previous
 examples.  We need to split the 64 member octet sequence of the JWS
 Signature (which is base64url decoded from the value encoded in the
 JWS representation) into two 32 octet sequences, the first
 representing R and the second S.  We then pass the public key (x, y),
 the signature (R, S), and the JWS Signing Input (which is the initial
 substring of the JWS Compact Serialization representation up until

Jones, et al. Standards Track [Page 45] RFC 7515 JSON Web Signature (JWS) May 2015

 but not including the second period character) to an ECDSA signature
 verifier that has been configured to use the P-256 curve with the
 SHA-256 hash function.

A.4. Example JWS Using ECDSA P-521 SHA-512

A.4.1. Encoding

 The JWS Protected Header for this example differs from the previous
 example because different ECDSA curves and hash functions are used.
 The JWS Protected Header used is:
   {"alg":"ES512"}
 The octets representing UTF8(JWS Protected Header) in this example
 (using JSON array notation) are:
 [123, 34, 97, 108, 103, 34, 58, 34, 69, 83, 53, 49, 50, 34, 125]
 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJhbGciOiJFUzUxMiJ9
 The JWS Payload used in this example is the ASCII string "Payload".
 The representation of this string is the following octet sequence:
 [80, 97, 121, 108, 111, 97, 100]
 Encoding this JWS Payload as BASE64URL(JWS Payload) gives this value:
   UGF5bG9hZA
 Combining these as BASE64URL(UTF8(JWS Protected Header)) || '.' ||
 BASE64URL(JWS Payload) gives this string:
   eyJhbGciOiJFUzUxMiJ9.UGF5bG9hZA
 The resulting JWS Signing Input value, which is the ASCII
 representation of above string, is the following octet sequence:
 [101, 121, 74, 104, 98, 71, 99, 105, 79, 105, 74, 70, 85, 122, 85,
 120, 77, 105, 74, 57, 46, 85, 71, 70, 53, 98, 71, 57, 104, 90, 65]

Jones, et al. Standards Track [Page 46] RFC 7515 JSON Web Signature (JWS) May 2015

 This example uses the Elliptic Curve key represented in JSON Web Key
 [JWK] format below (with line breaks within values for display
 purposes only):
   {"kty":"EC",
    "crv":"P-521",
    "x":"AekpBQ8ST8a8VcfVOTNl353vSrDCLLJXmPk06wTjxrrjcBpXp5EOnYG_
         NjFZ6OvLFV1jSfS9tsz4qUxcWceqwQGk",
    "y":"ADSmRA43Z1DSNx_RvcLI87cdL07l6jQyyBXMoxVg_l2Th-x3S1WDhjDl
         y79ajL4Kkd0AZMaZmh9ubmf63e3kyMj2",
    "d":"AY5pb7A0UFiB3RELSD64fTLOSV_jazdF7fLYyuTw8lOfRhWg6Y6rUrPA
         xerEzgdRhajnu0ferB0d53vM9mE15j2C"
   }
 The ECDSA private part d is then passed to an ECDSA signing function,
 which also takes the curve type, P-521, the hash type, SHA-512, and
 the JWS Signing Input as inputs.  The result of the digital signature
 is the EC point (R, S), where R and S are unsigned integers.  In this
 example, the R and S values, given as octet sequences representing
 big-endian integers are:
 +--------+----------------------------------------------------------+
 | Result | Value                                                    |
 | Name   |                                                          |
 +--------+----------------------------------------------------------+
 | R      | [1, 220, 12, 129, 231, 171, 194, 209, 232, 135, 233,     |
 |        | 117, 247, 105, 122, 210, 26, 125, 192, 1, 217, 21, 82,   |
 |        | 91, 45, 240, 255, 83, 19, 34, 239, 71, 48, 157, 147,     |
 |        | 152, 105, 18, 53, 108, 163, 214, 68, 231, 62, 153, 150,  |
 |        | 106, 194, 164, 246, 72, 143, 138, 24, 50, 129, 223, 133, |
 |        | 206, 209, 172, 63, 237, 119, 109]                        |
 | S      | [0, 111, 6, 105, 44, 5, 41, 208, 128, 61, 152, 40, 92,   |
 |        | 61, 152, 4, 150, 66, 60, 69, 247, 196, 170, 81, 193,     |
 |        | 199, 78, 59, 194, 169, 16, 124, 9, 143, 42, 142, 131,    |
 |        | 48, 206, 238, 34, 175, 83, 203, 220, 159, 3, 107, 155,   |
 |        | 22, 27, 73, 111, 68, 68, 21, 238, 144, 229, 232, 148,    |
 |        | 188, 222, 59, 242, 103]                                  |
 +--------+----------------------------------------------------------+
 The JWS Signature is the value R || S.  Encoding the signature as
 BASE64URL(JWS Signature) produces this value (with line breaks for
 display purposes only):
   AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq
   wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp
   EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn

Jones, et al. Standards Track [Page 47] RFC 7515 JSON Web Signature (JWS) May 2015

 Concatenating these values in the order Header.Payload.Signature with
 period ('.') characters between the parts yields this complete JWS
 representation using the JWS Compact Serialization (with line breaks
 for display purposes only):
   eyJhbGciOiJFUzUxMiJ9
   .
   UGF5bG9hZA
   .
   AdwMgeerwtHoh-l192l60hp9wAHZFVJbLfD_UxMi70cwnZOYaRI1bKPWROc-mZZq
   wqT2SI-KGDKB34XO0aw_7XdtAG8GaSwFKdCAPZgoXD2YBJZCPEX3xKpRwcdOO8Kp
   EHwJjyqOgzDO7iKvU8vcnwNrmxYbSW9ERBXukOXolLzeO_Jn

A.4.2. Validating

 Since the "alg" Header Parameter is "ES512", we validate the ECDSA
 P-521 SHA-512 digital signature contained in the JWS Signature.
 Validating this JWS Signature is very similar to the previous
 example.  We need to split the 132-member octet sequence of the JWS
 Signature into two 66-octet sequences, the first representing R and
 the second S.  We then pass the public key (x, y), the signature (R,
 S), and the JWS Signing Input to an ECDSA signature verifier that has
 been configured to use the P-521 curve with the SHA-512 hash
 function.

A.5. Example Unsecured JWS

 The following example JWS Protected Header declares that the encoded
 object is an Unsecured JWS:
   {"alg":"none"}
 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJhbGciOiJub25lIn0
 The JWS Payload used in this example, which follows, is the same as
 in the previous examples.  Since the BASE64URL(JWS Payload) value
 will therefore be the same, its computation is not repeated here.
   {"iss":"joe",
    "exp":1300819380,
    "http://example.com/is_root":true}
 The JWS Signature is the empty octet string and BASE64URL(JWS
 Signature) is the empty string.

Jones, et al. Standards Track [Page 48] RFC 7515 JSON Web Signature (JWS) May 2015

 Concatenating these values in the order Header.Payload.Signature with
 period ('.') characters between the parts yields this complete JWS
 representation using the JWS Compact Serialization (with line breaks
 for display purposes only):
   eyJhbGciOiJub25lIn0
   .
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
   .

A.6. Example JWS Using General JWS JSON Serialization

 This section contains an example using the general JWS JSON
 Serialization syntax.  This example demonstrates the capability for
 conveying multiple digital signatures and/or MACs for the same
 payload.
 The JWS Payload used in this example is the same as that used in the
 examples in Appendix A.2 and Appendix A.3 (with line breaks for
 display purposes only):
   eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFt
   cGxlLmNvbS9pc19yb290Ijp0cnVlfQ
 Two digital signatures are used in this example: the first using
 RSASSA-PKCS1-v1_5 SHA-256 and the second using ECDSA P-256 SHA-256.
 For the first, the JWS Protected Header and key are the same as in
 Appendix A.2, resulting in the same JWS Signature value; therefore,
 its computation is not repeated here.  For the second, the JWS
 Protected Header and key are the same as in Appendix A.3, resulting
 in the same JWS Signature value; therefore, its computation is not
 repeated here.

A.6.1. JWS Per-Signature Protected Headers

 The JWS Protected Header value used for the first signature is:
   {"alg":"RS256"}
 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJhbGciOiJSUzI1NiJ9
 The JWS Protected Header value used for the second signature is:
   {"alg":"ES256"}

Jones, et al. Standards Track [Page 49] RFC 7515 JSON Web Signature (JWS) May 2015

 Encoding this JWS Protected Header as BASE64URL(UTF8(JWS Protected
 Header)) gives this value:
   eyJhbGciOiJFUzI1NiJ9

A.6.2. JWS Per-Signature Unprotected Headers

 Key ID values are supplied for both keys using per-signature Header
 Parameters.  The two JWS Unprotected Header values used to represent
 these key IDs are:
   {"kid":"2010-12-29"}
 and
   {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}

A.6.3. Complete JOSE Header Values

 Combining the JWS Protected Header and JWS Unprotected Header values
 supplied, the JOSE Header values used for the first and second
 signatures, respectively, are:
   {"alg":"RS256",
    "kid":"2010-12-29"}
 and
   {"alg":"ES256",
    "kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"}

Jones, et al. Standards Track [Page 50] RFC 7515 JSON Web Signature (JWS) May 2015

A.6.4. Complete JWS JSON Serialization Representation

 The complete JWS JSON Serialization for these values is as follows
 (with line breaks within values for display purposes only):
   {
    "payload":
     "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
      tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ",
    "signatures":[
     {"protected":"eyJhbGciOiJSUzI1NiJ9",
      "header":
       {"kid":"2010-12-29"},
      "signature":
       "cC4hiUPoj9Eetdgtv3hF80EGrhuB__dzERat0XF9g2VtQgr9PJbu3XOiZj5RZ
        mh7AAuHIm4Bh-0Qc_lF5YKt_O8W2Fp5jujGbds9uJdbF9CUAr7t1dnZcAcQjb
        KBYNX4BAynRFdiuB--f_nZLgrnbyTyWzO75vRK5h6xBArLIARNPvkSjtQBMHl
        b1L07Qe7K0GarZRmB_eSN9383LcOLn6_dO--xi12jzDwusC-eOkHWEsqtFZES
        c6BfI7noOPqvhJ1phCnvWh6IeYI2w9QOYEUipUTI8np6LbgGY9Fs98rqVt5AX
        LIhWkWywlVmtVrBp0igcN_IoypGlUPQGe77Rw"},
     {"protected":"eyJhbGciOiJFUzI1NiJ9",
      "header":
       {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"},
      "signature":
       "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8IS
        lSApmWQxfKTUJqPP3-Kg6NU1Q"}]
   }

Jones, et al. Standards Track [Page 51] RFC 7515 JSON Web Signature (JWS) May 2015

A.7. Example JWS Using Flattened JWS JSON Serialization

 This section contains an example using the flattened JWS JSON
 Serialization syntax.  This example demonstrates the capability for
 conveying a single digital signature or MAC in a flattened JSON
 structure.
 The values in this example are the same as those in the second
 signature of the previous example in Appendix A.6.
 The complete JWS JSON Serialization for these values is as follows
 (with line breaks within values for display purposes only):
   {
    "payload":
     "eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGF
      tcGxlLmNvbS9pc19yb290Ijp0cnVlfQ",
    "protected":"eyJhbGciOiJFUzI1NiJ9",
    "header":
     {"kid":"e9bc097a-ce51-4036-9562-d2ade882db0d"},
    "signature":
     "DtEhU3ljbEg8L38VWAfUAqOyKAM6-Xx-F4GawxaepmXFCgfTjDxw5djxLa8IS
      lSApmWQxfKTUJqPP3-Kg6NU1Q"
   }

Jones, et al. Standards Track [Page 52] RFC 7515 JSON Web Signature (JWS) May 2015

Appendix B. "x5c" (X.509 Certificate Chain) Example

 The JSON array below is an example of a certificate chain that could
 be used as the value of an "x5c" (X.509 certificate chain) Header
 Parameter, per Section 4.1.6 (with line breaks within values for
 display purposes only):
   ["MIIE3jCCA8agAwIBAgICAwEwDQYJKoZIhvcNAQEFBQAwYzELMAkGA1UEBhMCVVM
     xITAfBgNVBAoTGFRoZSBHbyBEYWRkeSBHcm91cCwgSW5jLjExMC8GA1UECxMoR2
     8gRGFkZHkgQ2xhc3MgMiBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTAeFw0wNjExM
     TYwMTU0MzdaFw0yNjExMTYwMTU0MzdaMIHKMQswCQYDVQQGEwJVUzEQMA4GA1UE
     CBMHQXJpem9uYTETMBEGA1UEBxMKU2NvdHRzZGFsZTEaMBgGA1UEChMRR29EYWR
     keS5jb20sIEluYy4xMzAxBgNVBAsTKmh0dHA6Ly9jZXJ0aWZpY2F0ZXMuZ29kYW
     RkeS5jb20vcmVwb3NpdG9yeTEwMC4GA1UEAxMnR28gRGFkZHkgU2VjdXJlIENlc
     nRpZmljYXRpb24gQXV0aG9yaXR5MREwDwYDVQQFEwgwNzk2OTI4NzCCASIwDQYJ
     KoZIhvcNAQEBBQADggEPADCCAQoCggEBAMQt1RWMnCZM7DI161+4WQFapmGBWTt
     wY6vj3D3HKrjJM9N55DrtPDAjhI6zMBS2sofDPZVUBJ7fmd0LJR4h3mUpfjWoqV
     Tr9vcyOdQmVZWt7/v+WIbXnvQAjYwqDL1CBM6nPwT27oDyqu9SoWlm2r4arV3aL
     GbqGmu75RpRSgAvSMeYddi5Kcju+GZtCpyz8/x4fKL4o/K1w/O5epHBp+YlLpyo
     7RJlbmr2EkRTcDCVw5wrWCs9CHRK8r5RsL+H0EwnWGu1NcWdrxcx+AuP7q2BNgW
     JCJjPOq8lh8BJ6qf9Z/dFjpfMFDniNoW1fho3/Rb2cRGadDAW/hOUoz+EDU8CAw
     EAAaOCATIwggEuMB0GA1UdDgQWBBT9rGEyk2xF1uLuhV+auud2mWjM5zAfBgNVH
     SMEGDAWgBTSxLDSkdRMEXGzYcs9of7dqGrU4zASBgNVHRMBAf8ECDAGAQH/AgEA
     MDMGCCsGAQUFBwEBBCcwJTAjBggrBgEFBQcwAYYXaHR0cDovL29jc3AuZ29kYWR
     keS5jb20wRgYDVR0fBD8wPTA7oDmgN4Y1aHR0cDovL2NlcnRpZmljYXRlcy5nb2
     RhZGR5LmNvbS9yZXBvc2l0b3J5L2dkcm9vdC5jcmwwSwYDVR0gBEQwQjBABgRVH
     SAAMDgwNgYIKwYBBQUHAgEWKmh0dHA6Ly9jZXJ0aWZpY2F0ZXMuZ29kYWRkeS5j
     b20vcmVwb3NpdG9yeTAOBgNVHQ8BAf8EBAMCAQYwDQYJKoZIhvcNAQEFBQADggE
     BANKGwOy9+aG2Z+5mC6IGOgRQjhVyrEp0lVPLN8tESe8HkGsz2ZbwlFalEzAFPI
     UyIXvJxwqoJKSQ3kbTJSMUA2fCENZvD117esyfxVgqwcSeIaha86ykRvOe5GPLL
     5CkKSkB2XIsKd83ASe8T+5o0yGPwLPk9Qnt0hCqU7S+8MxZC9Y7lhyVJEnfzuz9
     p0iRFEUOOjZv2kWzRaJBydTXRE4+uXR21aITVSzGh6O1mawGhId/dQb8vxRMDsx
     uxN89txJx9OjxUUAiKEngHUuHqDTMBqLdElrRhjZkAzVvb3du6/KFUJheqwNTrZ
     EjYx8WnM25sgVjOuH0aBsXBTWVU+4=",
    "MIIE+zCCBGSgAwIBAgICAQ0wDQYJKoZIhvcNAQEFBQAwgbsxJDAiBgNVBAcTG1Z
     hbGlDZXJ0IFZhbGlkYXRpb24gTmV0d29yazEXMBUGA1UEChMOVmFsaUNlcnQsIE
     luYy4xNTAzBgNVBAsTLFZhbGlDZXJ0IENsYXNzIDIgUG9saWN5IFZhbGlkYXRpb
     24gQXV0aG9yaXR5MSEwHwYDVQQDExhodHRwOi8vd3d3LnZhbGljZXJ0LmNvbS8x
     IDAeBgkqhkiG9w0BCQEWEWluZm9AdmFsaWNlcnQuY29tMB4XDTA0MDYyOTE3MDY
     yMFoXDTI0MDYyOTE3MDYyMFowYzELMAkGA1UEBhMCVVMxITAfBgNVBAoTGFRoZS
     BHbyBEYWRkeSBHcm91cCwgSW5jLjExMC8GA1UECxMoR28gRGFkZHkgQ2xhc3MgM
     iBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTCCASAwDQYJKoZIhvcNAQEBBQADggEN
     ADCCAQgCggEBAN6d1+pXGEmhW+vXX0iG6r7d/+TvZxz0ZWizV3GgXne77ZtJ6XC
     APVYYYwhv2vLM0D9/AlQiVBDYsoHUwHU9S3/Hd8M+eKsaA7Ugay9qK7HFiH7Eux
     6wwdhFJ2+qN1j3hybX2C32qRe3H3I2TqYXP2WYktsqbl2i/ojgC95/5Y0V4evLO
     tXiEqITLdiOr18SPaAIBQi2XKVlOARFmR6jYGB0xUGlcmIbYsUfb18aQr4CUWWo
     riMYavx4A6lNf4DD+qta/KFApMoZFv6yyO9ecw3ud72a9nmYvLEHZ6IVDd2gWMZ
     Eewo+YihfukEHU1jPEX44dMX4/7VpkI+EdOqXG68CAQOjggHhMIIB3TAdBgNVHQ

Jones, et al. Standards Track [Page 53] RFC 7515 JSON Web Signature (JWS) May 2015

     4EFgQU0sSw0pHUTBFxs2HLPaH+3ahq1OMwgdIGA1UdIwSByjCBx6GBwaSBvjCBu
     zEkMCIGA1UEBxMbVmFsaUNlcnQgVmFsaWRhdGlvbiBOZXR3b3JrMRcwFQYDVQQK
     Ew5WYWxpQ2VydCwgSW5jLjE1MDMGA1UECxMsVmFsaUNlcnQgQ2xhc3MgMiBQb2x
     pY3kgVmFsaWRhdGlvbiBBdXRob3JpdHkxITAfBgNVBAMTGGh0dHA6Ly93d3cudm
     FsaWNlcnQuY29tLzEgMB4GCSqGSIb3DQEJARYRaW5mb0B2YWxpY2VydC5jb22CA
     QEwDwYDVR0TAQH/BAUwAwEB/zAzBggrBgEFBQcBAQQnMCUwIwYIKwYBBQUHMAGG
     F2h0dHA6Ly9vY3NwLmdvZGFkZHkuY29tMEQGA1UdHwQ9MDswOaA3oDWGM2h0dHA
     6Ly9jZXJ0aWZpY2F0ZXMuZ29kYWRkeS5jb20vcmVwb3NpdG9yeS9yb290LmNybD
     BLBgNVHSAERDBCMEAGBFUdIAAwODA2BggrBgEFBQcCARYqaHR0cDovL2NlcnRpZ
     mljYXRlcy5nb2RhZGR5LmNvbS9yZXBvc2l0b3J5MA4GA1UdDwEB/wQEAwIBBjAN
     BgkqhkiG9w0BAQUFAAOBgQC1QPmnHfbq/qQaQlpE9xXUhUaJwL6e4+PrxeNYiY+
     Sn1eocSxI0YGyeR+sBjUZsE4OWBsUs5iB0QQeyAfJg594RAoYC5jcdnplDQ1tgM
     QLARzLrUc+cb53S8wGd9D0VmsfSxOaFIqII6hR8INMqzW/Rn453HWkrugp++85j
     09VZw==",
    "MIIC5zCCAlACAQEwDQYJKoZIhvcNAQEFBQAwgbsxJDAiBgNVBAcTG1ZhbGlDZXJ
     0IFZhbGlkYXRpb24gTmV0d29yazEXMBUGA1UEChMOVmFsaUNlcnQsIEluYy4xNT
     AzBgNVBAsTLFZhbGlDZXJ0IENsYXNzIDIgUG9saWN5IFZhbGlkYXRpb24gQXV0a
     G9yaXR5MSEwHwYDVQQDExhodHRwOi8vd3d3LnZhbGljZXJ0LmNvbS8xIDAeBgkq
     hkiG9w0BCQEWEWluZm9AdmFsaWNlcnQuY29tMB4XDTk5MDYyNjAwMTk1NFoXDTE
     5MDYyNjAwMTk1NFowgbsxJDAiBgNVBAcTG1ZhbGlDZXJ0IFZhbGlkYXRpb24gTm
     V0d29yazEXMBUGA1UEChMOVmFsaUNlcnQsIEluYy4xNTAzBgNVBAsTLFZhbGlDZ
     XJ0IENsYXNzIDIgUG9saWN5IFZhbGlkYXRpb24gQXV0aG9yaXR5MSEwHwYDVQQD
     ExhodHRwOi8vd3d3LnZhbGljZXJ0LmNvbS8xIDAeBgkqhkiG9w0BCQEWEWluZm9
     AdmFsaWNlcnQuY29tMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDOOnHK5a
     vIWZJV16vYdA757tn2VUdZZUcOBVXc65g2PFxTXdMwzzjsvUGJ7SVCCSRrCl6zf
     N1SLUzm1NZ9WlmpZdRJEy0kTRxQb7XBhVQ7/nHk01xC+YDgkRoKWzk2Z/M/VXwb
     P7RfZHM047QSv4dk+NoS/zcnwbNDu+97bi5p9wIDAQABMA0GCSqGSIb3DQEBBQU
     AA4GBADt/UG9vUJSZSWI4OB9L+KXIPqeCgfYrx+jFzug6EILLGACOTb2oWH+heQ
     C1u+mNr0HZDzTuIYEZoDJJKPTEjlbVUjP9UNV+mWwD5MlM/Mtsq2azSiGM5bUMM
     j4QssxsodyamEwCW/POuZ6lcg5Ktz885hZo+L7tdEy8W9ViH0Pd"]

Jones, et al. Standards Track [Page 54] RFC 7515 JSON Web Signature (JWS) May 2015

Appendix C. Notes on Implementing base64url Encoding without Padding

 This appendix describes how to implement base64url encoding and
 decoding functions without padding based upon standard base64
 encoding and decoding functions that do use padding.
 To be concrete, example C# code implementing these functions is shown
 below.  Similar code could be used in other languages.
   static string base64urlencode(byte [] arg)
   {
     string s = Convert.ToBase64String(arg); // Regular base64 encoder
     s = s.Split('=')[0]; // Remove any trailing '='s
     s = s.Replace('+', '-'); // 62nd char of encoding
     s = s.Replace('/', '_'); // 63rd char of encoding
     return s;
   }
   static byte [] base64urldecode(string arg)
   {
     string s = arg;
     s = s.Replace('-', '+'); // 62nd char of encoding
     s = s.Replace('_', '/'); // 63rd char of encoding
     switch (s.Length % 4) // Pad with trailing '='s
     {
       case 0: break; // No pad chars in this case
       case 2: s += "=="; break; // Two pad chars
       case 3: s += "="; break; // One pad char
       default: throw new System.Exception(
         "Illegal base64url string!");
     }
     return Convert.FromBase64String(s); // Standard base64 decoder
   }
 As per the example code above, the number of '=' padding characters
 that needs to be added to the end of a base64url-encoded string
 without padding to turn it into one with padding is a deterministic
 function of the length of the encoded string.  Specifically, if the
 length mod 4 is 0, no padding is added; if the length mod 4 is 2, two
 '=' padding characters are added; if the length mod 4 is 3, one '='
 padding character is added; if the length mod 4 is 1, the input is
 malformed.

Jones, et al. Standards Track [Page 55] RFC 7515 JSON Web Signature (JWS) May 2015

 An example correspondence between unencoded and encoded values
 follows.  The octet sequence below encodes into the string below,
 which when decoded, reproduces the octet sequence.
 3 236 255 224 193
 A-z_4ME

Appendix D. Notes on Key Selection

 This appendix describes a set of possible algorithms for selecting
 the key to be used to validate the digital signature or MAC of a JWS
 or for selecting the key to be used to decrypt a JWE.  This guidance
 describes a family of possible algorithms rather than a single
 algorithm, because in different contexts, not all the sources of keys
 will be used, they can be tried in different orders, and sometimes
 not all the collected keys will be tried; hence, different algorithms
 will be used in different application contexts.
 The steps below are described for illustration purposes only;
 specific applications can and are likely to use different algorithms
 or perform some of the steps in different orders.  Specific
 applications will frequently have a much simpler method of
 determining the keys to use, as there may be one or two key selection
 methods that are profiled for the application's use.  This appendix
 supplements the normative information on key location in Section 6.
 These algorithms include the following steps.  Note that the steps
 can be performed in any order and do not need to be treated as
 distinct.  For example, keys can be tried as soon as they are found,
 rather than collecting all the keys before trying any.
 1.  Collect the set of potentially applicable keys.  Sources of keys
     may include:
  • Keys supplied by the application protocol being used.
  • Keys referenced by the "jku" (JWK Set URL) Header Parameter.
  • The key provided by the "jwk" (JSON Web Key) Header Parameter.
  • The key referenced by the "x5u" (X.509 URL) Header Parameter.
  • The key provided by the "x5c" (X.509 certificate chain) Header

Parameter.

  • Other applicable keys available to the application.

Jones, et al. Standards Track [Page 56] RFC 7515 JSON Web Signature (JWS) May 2015

     The order for collecting and trying keys from different key
     sources is typically application dependent.  For example,
     frequently, all keys from a one set of locations, such as local
     caches, will be tried before collecting and trying keys from
     other locations.
 2.  Filter the set of collected keys.  For instance, some
     applications will use only keys referenced by "kid" (key ID) or
     "x5t" (X.509 certificate SHA-1 thumbprint) parameters.  If the
     application uses the JWK "alg" (algorithm), "use" (public key
     use), or "key_ops" (key operations) parameters, keys with
     inappropriate values of those parameters would be excluded.
     Additionally, keys might be filtered to include or exclude keys
     with certain other member values in an application-specific
     manner.  For some applications, no filtering will be applied.
 3.  Order the set of collected keys.  For instance, keys referenced
     by "kid" (key ID) or "x5t" (X.509 certificate SHA-1 thumbprint)
     parameters might be tried before keys with neither of these
     values.  Likewise, keys with certain member values might be
     ordered before keys with other member values.  For some
     applications, no ordering will be applied.
 4.  Make trust decisions about the keys.  Signatures made with keys
     not meeting the application's trust criteria would not be
     accepted.  Such criteria might include, but is not limited to,
     the source of the key, whether the TLS certificate validates for
     keys retrieved from URLs, whether a key in an X.509 certificate
     is backed by a valid certificate chain, and other information
     known by the application.
 5.  Attempt signature or MAC validation for a JWS or decryption of a
     JWE with some or all of the collected and possibly filtered and/
     or ordered keys.  A limit on the number of keys to be tried might
     be applied.  This process will normally terminate following a
     successful validation or decryption.
 Note that it is reasonable for some applications to perform signature
 or MAC validation prior to making a trust decision about a key, since
 keys for which the validation fails need no trust decision.

Jones, et al. Standards Track [Page 57] RFC 7515 JSON Web Signature (JWS) May 2015

Appendix E. Negative Test Case for "crit" Header Parameter

 Conforming implementations must reject input containing critical
 extensions that are not understood or cannot be processed.  The
 following JWS must be rejected by all implementations, because it
 uses an extension Header Parameter name "http://example.invalid/
 UNDEFINED" that they do not understand.  Any other similar input, in
 which the use of the value "http://example.invalid/UNDEFINED" is
 substituted for any other Header Parameter name not understood by the
 implementation, must also be rejected.
 The JWS Protected Header value for this JWS is:
   {"alg":"none",
    "crit":["http://example.invalid/UNDEFINED"],
    "http://example.invalid/UNDEFINED":true
   }
 The complete JWS that must be rejected is as follows (with line
 breaks for display purposes only):
   eyJhbGciOiJub25lIiwNCiAiY3JpdCI6WyJodHRwOi8vZXhhbXBsZS5jb20vVU5ERU
   ZJTkVEIl0sDQogImh0dHA6Ly9leGFtcGxlLmNvbS9VTkRFRklORUQiOnRydWUNCn0.
   RkFJTA.

Appendix F. Detached Content

 In some contexts, it is useful to integrity-protect content that is
 not itself contained in a JWS.  One way to do this is to create a JWS
 in the normal fashion using a representation of the content as the
 payload but then delete the payload representation from the JWS and
 send this modified object to the recipient rather than the JWS.  When
 using the JWS Compact Serialization, the deletion is accomplished by
 replacing the second field (which contains BASE64URL(JWS Payload))
 value with the empty string; when using the JWS JSON Serialization,
 the deletion is accomplished by deleting the "payload" member.  This
 method assumes that the recipient can reconstruct the exact payload
 used in the JWS.  To use the modified object, the recipient
 reconstructs the JWS by re-inserting the payload representation into
 the modified object and uses the resulting JWS in the usual manner.
 Note that this method needs no support from JWS libraries, as
 applications can use this method by modifying the inputs and outputs
 of standard JWS libraries.

Jones, et al. Standards Track [Page 58] RFC 7515 JSON Web Signature (JWS) May 2015

Acknowledgements

 Solutions for signing JSON content were previously explored by Magic
 Signatures [MagicSignatures], JSON Simple Sign [JSS], and Canvas
 Applications [CanvasApp], all of which influenced this document.
 Thanks to Axel Nennker for his early implementation and feedback on
 the JWS and JWE specifications.
 This specification is the work of the JOSE working group, which
 includes dozens of active and dedicated participants.  In particular,
 the following individuals contributed ideas, feedback, and wording
 that influenced this specification:
 Dirk Balfanz, Richard Barnes, Brian Campbell, Alissa Cooper, Breno de
 Medeiros, Stephen Farrell, Yaron Y. Goland, Dick Hardt, Joe
 Hildebrand, Jeff Hodges, Russ Housley, Edmund Jay, Tero Kivinen, Ben
 Laurie, Ted Lemon, James Manger, Matt Miller, Kathleen Moriarty, Tony
 Nadalin, Hideki Nara, Axel Nennker, John Panzer, Ray Polk, Emmanuel
 Raviart, Eric Rescorla, Pete Resnick, Jim Schaad, Paul Tarjan, Hannes
 Tschofenig, and Sean Turner.
 Jim Schaad and Karen O'Donoghue chaired the JOSE working group and
 Sean Turner, Stephen Farrell, and Kathleen Moriarty served as
 Security Area Directors during the creation of this specification.

Authors' Addresses

 Michael B. Jones
 Microsoft
 EMail: mbj@microsoft.com
 URI:   http://self-issued.info/
 John Bradley
 Ping Identity
 EMail: ve7jtb@ve7jtb.com
 URI:   http://www.thread-safe.com/
 Nat Sakimura
 Nomura Research Institute
 EMail: n-sakimura@nri.co.jp
 URI:   http://nat.sakimura.org/

Jones, et al. Standards Track [Page 59]

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