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rfc:rfc6239

Internet Engineering Task Force (IETF) K. Igoe Request for Comments: 6239 National Security Agency Category: Informational May 2011 ISSN: 2070-1721

        Suite B Cryptographic Suites for Secure Shell (SSH)

Abstract

 This document describes the architecture of a Suite B compliant
 implementation of the Secure Shell Transport Layer Protocol and the
 Secure Shell Authentication Protocol.  Suite B Secure Shell makes use
 of the elliptic curve Diffie-Hellman (ECDH) key agreement, the
 elliptic curve digital signature algorithm (ECDSA), the Advanced
 Encryption Standard running in Galois/Counter Mode (AES-GCM), two
 members of the SHA-2 family of hashes (SHA-256 and SHA-384), and
 X.509 certificates.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 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).  Not all documents
 approved by the IESG are a candidate for any level of Internet
 Standard; see 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/rfc6239.

Igoe Informational [Page 1] RFC 6239 Suite B Crypto Suites for SSH May 2011

Copyright Notice

 Copyright (c) 2011 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 ....................................................3
 2. Suite B and Secure Shell ........................................3
    2.1. Minimum Levels of Security (minLOS) ........................4
    2.2. Digital Signatures and Certificates ........................4
    2.3. Non-Signature Primitives ...................................5
 3. Security Mechanism Negotiation and Initialization ...............6
    3.1. Algorithm Negotiation: SSH_MSG_KEXINIT .....................7
 4. Key Exchange and Server Authentication ..........................8
    4.1. SSH_MSG_KEXECDH_INIT .......................................9
    4.2. SSH_MSG_KEXECDH_REPLY ......................................9
    4.3. Key and Initialization Vector Derivation ..................10
 5. User Authentication ............................................10
    5.1. First SSH_MSG_USERAUTH_REQUEST Message ....................10
    5.2. Second SSH_MSG_USERAUTH_REQUEST Message ...................11
 6. Confidentiality and Data Integrity of SSH Binary Packets .......12
    6.1. Galois/Counter Mode .......................................12
    6.2. Data Integrity ............................................12
 7. Rekeying .......................................................12
 8. Security Considerations ........................................13
 9. References .....................................................13
    9.1. Normative References ......................................13
    9.2. Informative References ....................................13

Igoe Informational [Page 2] RFC 6239 Suite B Crypto Suites for SSH May 2011

1. Introduction

 This document describes the architecture of a Suite B compliant
 implementation of the Secure Shell Transport Layer Protocol and the
 Secure Shell Authentication Protocol.  Suite B Secure Shell makes use
 of the elliptic curve Diffie-Hellman (ECDH) key agreement, the
 elliptic curve digital signature algorithm (ECDSA), the Advanced
 Encryption Standard running in Galois/Counter Mode (AES-GCM), two
 members of the SHA-2 family of hashes (SHA-256 and SHA-384), and
 X.509 certificates.
 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [RFC2119].

2. Suite B and Secure Shell

 Several RFCs have documented how each of the Suite B components are
 to be integrated into Secure Shell (SSH):
   kex algorithms
         ecdh-sha2-nistp256           [SSH-ECC]
         ecdh-sha2-nistp384           [SSH-ECC]
   server host key algorithms
         x509v3-ecdsa-sha2-nistp256   [SSH-X509]
         x509v3-ecdsa-sha2-nistp384   [SSH-X509]
   encryption algorithms (both client_to_server and server_to_client)
         AEAD_AES_128_GCM             [SSH-GCM]
         AEAD_AES_256_GCM             [SSH-GCM]
   MAC algorithms (both client_to_server and server_to_client)
         AEAD_AES_128_GCM             [SSH-GCM]
         AEAD_AES_256_GCM             [SSH-GCM]
 In Suite B, public key certificates used to verify signatures MUST be
 compliant with the Suite B Certificate Profile specified in RFC 5759
 [SUITEBCERT].
 The purpose of this document is to draw upon all of these documents
 to provide guidance for Suite B compliant implementations of Secure
 Shell (hereafter referred to as "SecSh-B").  Note that while SecSh-B
 MUST follow the guidance in this document, that requirement does not
 in and of itself imply that a given implementation of Secure Shell is
 suitable for use in protecting classified data.  An implementation of
 SecSh-B must be validated by the appropriate authority before such
 usage is permitted.

Igoe Informational [Page 3] RFC 6239 Suite B Crypto Suites for SSH May 2011

 The two elliptic curves used in Suite B appear in the literature
 under two different names.  For the sake of clarity, we list both
 names below.
    Curve        NIST name        SECG name     OID [SEC2]
    ---------------------------------------------------------------
    P-256        nistp256         secp256r1     1.2.840.10045.3.1.7
    P-384        nistp384         secp384r1     1.3.132.0.34
 A description of these curves can be found in [NIST] or [SEC2].
 For the sake of brevity, ECDSA-256 will be used to denote ECDSA on
 P-256 using SHA-256, and ECDSA-384 will be used to denote ECDSA on
 P-384 using SHA-384.

2.1. Minimum Levels of Security (minLOS)

 Suite B provides for two levels of cryptographic security, namely a
 128-bit minimum level of security (minLOS_128) and a 192-bit minimum
 level of security (minLOS_192).  As we shall see below, the
 ECDSA-256/384 signature algorithms and corresponding X.509v3
 certificates are treated somewhat differently than the non-signature
 primitives (kex algorithms, encryption algorithms, and Message
 Authentication Code (MAC) algorithms in Secure Shell parlance).

2.2. Digital Signatures and Certificates

 SecSh-B uses ECDSA-256/384 for server authentication, user
 authentication, and in X.509 certificates.  [SSH-X509] defines two
 methods, x509v3-ecdsa-sha2-nistp256 and x509v3-ecdsa-sha2-nistp384,
 that are to be used for server and user authentication.  The
 following conditions must be met:
 1) The server MUST share its public key with the host using an
    X.509v3 certificate as described in [SSH-X509].  This public key
    MUST be used to authenticate the server to the host using
    ECDSA-256 or ECDSA-384 as appropriate (see Section 3).
 2) User authentication MUST begin with public key authentication
    using ECDSA-256/384 with X.509v3 certificates (see Section 4).
    Additional user authentication methods MAY be used, but only after
    the certificate-based ECDSA authentication has been successfully
    completed.
 3) The X.509v3 certificates MUST use only the two Suite B digital
    signatures, ECDSA-256 and ECDSA-384.
 4) ECDSA-256 MUST NOT be used to sign an ECDSA-384 public key.

Igoe Informational [Page 4] RFC 6239 Suite B Crypto Suites for SSH May 2011

 5) ECDSA-384 MAY be used to sign an ECDSA-256 public key.
 6) At minLOS_192, all SecSh-B implementations MUST be able to verify
    ECDSA-384 signatures.
 7) At minLOS_128, all SecSh-B implementations MUST be able to verify
    ECDSA-256 signatures and SHOULD be able to verify ECDSA-384
    signatures, unless it is absolutely certain that the
    implementation will never need to verify certificates originating
    from an authority that uses an ECDSA-384 signing key.
 8) At minLOS_128, each SecSh-B server and each SecSh-B user MUST have
    either an ECDSA-256 signing key with a corresponding X.509v3
    certificate, an ECDSA-384 signing key with a corresponding X.509v3
    certificate, or both.
 9) At minLOS_192, each SecSh-B server and each SecSh-B user MUST have
    an ECDSA-384 signing key with a corresponding X.509v3 certificate.
 The selection of the signature algorithm to be used for server
 authentication is governed by the server_host_key_algorithms name-
 list in the SSH_MSG_KEXINIT packet (see Section 3.1).  The key
 exchange and server authentication are performed by the
 SSH_MSG_KEXECDH_REPLY packets (see Section 4).  User authentication
 is done via the SSH_MSG_USERAUTH_REQUEST messages (see Section 5).

2.3. Non-Signature Primitives

 This section covers the constraints that the choice of minimum
 security level imposes upon the selection of a key agreement protocol
 (kex algorithm), encryption algorithm, and data integrity algorithm
 (MAC algorithm).  We divide the non-signature algorithms into two
 families, as shown in Table 1.
    +--------------+----------------------+----------------------+
    |  Algorithm   |  Family 1            |  Family 2            |
    +==============+======================+======================+
    |  kex         |  ecdh-sha2-nistp256  |  ecdh-sha2-nistp384  |
    +--------------+----------------------+----------------------+
    |  encryption  |  AEAD_AES_128_GCM    |  AEAD_AES_256_GCM    |
    +--------------+----------------------+----------------------+
    |  MAC         |  AEAD_AES_128_GCM    |  AEAD_AES_256_GCM    |
    +--------------+-----------------------+---------------------+
      Table 1.  Families of Non-Signature Algorithms in SecSh-B

Igoe Informational [Page 5] RFC 6239 Suite B Crypto Suites for SSH May 2011

 At the 128-bit minimum level of security:
 o  The non-signature algorithms MUST either come exclusively from
    Family 1 or exclusively from Family 2.
 o  The selection of Family 1 versus Family 2 is independent of the
    choice of server host key algorithm.
 At the 192-bit minimum level of security:
 o  The non-signature algorithms MUST all come from Family 2.
 Most of the constraints described in this section can be achieved by
 severely restricting the kex_algorithm, encryption_algorithm, and
 mac_algorithm name lists offered in the SSH_MSG_KEXINIT packet.  See
 Section 3.1 for details.

3. Security Mechanism Negotiation and Initialization

 As described in [SSH-Tran], the exchange of SSH_MSG_KEXINIT between
 the server and the client establishes which key agreement algorithm,
 MAC algorithm, host key algorithm (server authentication algorithm),
 and encryption algorithm are to be used.  This section describes how
 the Suite B components are to be used in the Secure Shell algorithm
 negotiation, key agreement, server authentication, and user
 authentication.
 Negotiation and initialization of a Suite B Secure Shell connection
 involves the following Secure Shell messages (where C->S denotes a
 message from the client to the server, and S->C denotes a server-to-
 client message):
    SSH_MSG_KEXINIT           C->S  Contains lists of algorithms
                                    acceptable to the client.
    SSH_MSG_KEXINIT           S->C  Contains lists of algorithms
                                    acceptable to the server.
    SSH_MSG_KEXECDH_INIT      C->S  Contains the client's ephemeral
                                    elliptic curve Diffie-Hellman key.
    SSH_MSG_KEXECDH_REPLY     S->C  Contains a certificate with the
                                    server's ECDSA public signature
                                    key, the server's ephemeral ECDH
                                    contribution, and an ECDSA digital
                                    signature of the newly formed
                                    exchange hash value.

Igoe Informational [Page 6] RFC 6239 Suite B Crypto Suites for SSH May 2011

    SSH_MSG_USERAUTH_REQUEST  C->S  Contains the user's name, the
                                    name of the service the user is
                                    requesting, the name of the
                                    authentication method the client
                                    wishes to use, and method-specific
                                    fields.
 When not in the midst of processing a key exchange, either party may
 initiate a key re-exchange by sending an SSH_MSG_KEXINIT packet.  All
 packets exchanged during the re-exchange are encrypted and
 authenticated using the current keys until the conclusion of the
 re-exchange, at which point an SSH_MSG_NEWKEYS initiates a change to
 the newly established keys.  Otherwise, the re-exchange protocol is
 identical to the initial key exchange protocol.  See Section 9 of
 [SSH-Tran].

3.1. Algorithm Negotiation: SSH_MSG_KEXINIT

 The choice of all but the user authentication methods are determined
 by the exchange of SSH_MSG_KEXINIT between the client and the server.
 As described in [SSH-Tran], the SSH_MSG_KEXINIT packet has the
 following structure:
    byte         SSH_MSG_KEXINIT
    byte[16]     cookie (random bytes)
    name-list    kex_algorithms
    name-list    server_host_key_algorithms
    name-list    encryption_algorithms_client_to_server
    name-list    encryption_algorithms_server_to_client
    name-list    mac_algorithms_client_to_server
    name-list    mac_algorithms_server_to_client
    name-list    compression_algorithms_client_to_server
    name-list    compression_algorithms_server_to_client
    name-list    languages_client_to_server
    name-list    languages_server_to_client
    boolean      first_kex_packet_follows
    uint32       0 (reserved for future extension)
 The SSH_MSG_KEXINIT name lists can be used to constrain the choice of
 non-signature and host key algorithms in accordance with the guidance
 given in Section 2.  Table 2 lists three allowable name lists for the
 non-signature algorithms.  One of these options MUST be used.

Igoe Informational [Page 7] RFC 6239 Suite B Crypto Suites for SSH May 2011

     Family 1 only (min_LOS 128):
        kex_algorithm name_list         := { ecdh_sha2_nistp256 }
        encryption_algorithm name_list  := { AEAD_AES_128_GCM   }
        mac_algorithm name_list         := { AEAD_AES_128_GCM   }
     Family 2 only (min_LOS 128 or 192):
        kex_algorithm name_list         := { ecdh_sha2_nistp384 }
        encryption_algorithm name_list  := { AEAD_AES_256_GCM   }
        mac_algorithm name_list         := { AEAD_AES_256_GCM   }
     Family 1 or Family 2 (min_LOS 128):
        kex_algorithm name_list         := { ecdh_sha2_nistp256,
                                             ecdh_sha2_nistp384 }
        encryption_algorithm name_list  := { AEAD_AES_128_GCM,
                                             AEAD_AES_256_GCM   }
        mac_algorithm name_list         := { AEAD_AES_128_GCM,
                                             AEAD_AES_256_GCM   }
         Table 2.  Allowed Non-Signature Algorithm Name Lists
 Table 3 lists three allowable name lists for the server host key
 algorithms.  One of these options MUST be used.
          ECDSA-256 only (min_LOS 128):
             server_host_key_algorithms name_list :=
                              { x509v3-ecdsa-sha2-nistp256 }
          ECDSA-384 only (min_LOS 128 or 192):
             server_host_key_algorithms name_list :=
                              { x509v3-ecdsa-sha2-nistp384 }
          ECDSA-256 or ECDSA-384 (min_LOS 128):
             server_host_key_algorithms name_list :=
                              { x509v3-ecdsa-sha2-nistp256,
                                x509v3-ecdsa-sha2-nistp384 }
        Table 3.  Allowed Server Host Key Algorithm Name Lists

4. Key Exchange and Server Authentication

 SecSh-B uses ECDH to establish a shared secret value between the
 client and the server.  An X.509v3 certificate containing the
 server's public signing ECDSA key and an ECDSA signature on the
 exchange hash value derived from the newly established shared secret
 value are used to authenticate the server to the client.

Igoe Informational [Page 8] RFC 6239 Suite B Crypto Suites for SSH May 2011

4.1. SSH_MSG_KEXECDH_INIT

 The key exchange to be used in Secure Shell is determined by the name
 lists exchanged in the SSH_MSG_KEXINIT packets.  In Suite B, one of
 the following key agreement methods MUST be used to generate a shared
 secret value (SSV):
    ecdh-sha2-nistp256      ephemeral-ephemeral elliptic curve
                            Diffie-Hellman on nistp256 with SHA-256
    ecdh-sha2-nistp384      ephemeral-ephemeral elliptic curve
                            Diffie-Hellman on nistp384 with SHA-384
 and the format of the SSH_MSG_KEXECDH_INIT message is:
    byte      SSH_MSG_KEXDH_INIT
    string    Q_C    // the client's ephemeral contribution to the
                     // ECDH exchange, encoded as an octet string
 where the encoding of the elliptic curve point Q_C as an octet string
 is as specified in Section 2.3.3 of [SEC1].

4.2. SSH_MSG_KEXECDH_REPLY

 The SSH_MSG_KEXECDH_REPLY contains the server's contribution to the
 ECDH exchange, the server's public signature key, and a signature of
 the exchange hash value formed from the newly established shared
 secret value.  As stated in Section 3.1, in SecSh-B, the server host
 key algorithm MUST be either x509v3-ecdsa-sha2-nistp256 or
 x509v3-ecdsa-sha2-nistp384.
 The format of the SSH_MSG_KEXECDH_REPLY is:
    byte      SSH_MSG_KEXECDH_REPLY
    string    K_S    // a string encoding an X.509v3 certificate
                     // containing the server's ECDSA public host key
    string    Q_S    // the server's ephemeral contribution to the
                     // ECDH exchange, encoded as an octet string
    string    Sig_S  // an octet string containing the server's
                     // signature of the newly established exchange
                     // hash value

Igoe Informational [Page 9] RFC 6239 Suite B Crypto Suites for SSH May 2011

 Details on the structure and encoding of the X.509v3 certificate can
 be found in Section 2 of [SSH-X509].  The encoding of the elliptic
 curve point Q_C as an octet string is as specified in Section 2.3.3
 of [SEC1], and the encoding of the ECDSA signature Sig_S as an octet
 string is as described in Section 3.1.2 of [SSH-ECC].

4.3. Key and Initialization Vector Derivation

 As specified in [SSH-Tran], the encryption keys and initialization
 vectors needed by Secure Shell are derived directly from the SSV
 using the hash function specified by the key agreement algorithm
 (SHA-256 for ecdh-sha2-nistp256 and SHA-384 for ecdh-sha2-nistp384).
 The client-to-server channel and the server-to-client channel will
 have independent keys and initialization vectors.  These keys will
 remain constant until a re-exchange results in the formation of a
 new SSV.

5. User Authentication

 The Secure Shell Transport Layer Protocol authenticates the server to
 the host but does not authenticate the user (or the user's host) to
 the server.  For this reason, condition (2) of Section 2.2 requires
 that all users of SecSh-B MUST be authenticated using ECDSA-256/384
 signatures and X.509v3 certificates.  [SSH-X509] provides two
 methods, x509v3-ecdsa-sha2-nistp256 and x509v3-ecdsa-sha2-nistp384,
 that MUST be used to achieve this goal.  At minLOS 128, either one of
 these methods may be used, but at minLOS 192,
 x509v3-ecdsa-sha2-nistp384 MUST be used.

5.1. First SSH_MSG_USERAUTH_REQUEST Message

 The user's public key is sent to the server using an
 SSH_MSG_USERAUTH_REQUEST message.  When an x509v3-ecdsa-sha2-* user
 authentication method is being used, the structure of the
 SSH_MSG_USERAUTH_REQUEST message should be:
    byte      SSH_MSG_USERAUTH_REQUEST
    string    user_name      // in ISO-10646 UTF-8 encoding
    string    service_name   // service name in US-ASCII
    string    "publickey"
    boolean   FALSE

Igoe Informational [Page 10] RFC 6239 Suite B Crypto Suites for SSH May 2011

    string    public_key_algorithm_name  // x509v3-ecdsa-sha2-nistp256
                                      // or x509v3-ecdsa-sha2-nistp384
    string    public_key_blob // X.509v3 certificate
 Details on the structure and encoding of the X.509v3 certificate can
 be found in Section 2 of [SSH-X509].

5.2. Second SSH_MSG_USERAUTH_REQUEST Message

 Once the server has responded to the request message with an
 SSH_MSG_USERAUTH_PK_OK message, the client uses a second
 SSH_MSG_USERAUTH_REQUEST message to perform the actual
 authentication:
    byte      SSH_MSG_USERAUTH_REQUEST
    string    user_name      // in ISO-10646 UTF-8 encoding
    string    service_name   // service name in US-ASCII
    string    "publickey"
    boolean   TRUE
    string    public_key_algorithm_name  // x509v3-ecdsa-sha2-nistp256
                                      // or x509v3-ecdsa-sha2-nistp384
    string    Sig_U
 The signature field Sig_U is an ECDSA signature of the concatenation
 of several values, including the session identifier, user name,
 service name, public key algorithm name, and the user's public
 signing key.  The user's public signing key MUST be the signing key
 conveyed in the X.509v3 certificate sent in the first
 SSH_MSG_USERAUTH_REQUEST message.  The encoding of the ECDSA
 signature Sig_U as an octet string is as described in Section 3.1.2
 of [SSH-ECC].
 The server MUST respond with either SSH_MSG_USERAUTH_SUCCESS (if no
 more authentications are needed) or SSH_MSG_USERAUTH_FAILURE (if the
 request failed, or more authentications are needed).

Igoe Informational [Page 11] RFC 6239 Suite B Crypto Suites for SSH May 2011

6. Confidentiality and Data Integrity of SSH Binary Packets

 Secure Shell transfers data between the client and the server using
 its own binary packet structure.  The SSH binary packet structure is
 independent of any packet structure on the underlying data channel.
 The contents of each binary packet and portions of the header are
 encrypted, and each packet is authenticated with its own message
 authentication code.  AES GCM will both encrypt the packet and form a
 16-octet authentication tag to ensure data integrity.

6.1. Galois/Counter Mode

 [SSH-GCM] describes how AES Galois/Counter Mode is to be used in
 Secure Shell.  Suite B SSH implementations MUST support
 AEAD_AES_GCM_128 and SHOULD support AEAD_AES_GCM_256 to both provide
 confidentiality and ensure data integrity.  No other confidentiality
 or data integrity algorithms are permitted.
 These algorithms rely on two counters:
    Invocation Counter: A 64-bit integer, incremented after each call
    to AES-GCM to process an SSH binary packet.  The initial value of
    the invocation counter is determined by the SSH initialization
    vector.
    Block Counter: A 32-bit integer, set to one at the start of each
    new SSH binary packet and incremented as each 16-octet block of
    data is processed.
 Ensuring that these counters are properly implemented is crucial to
 the security of the system.  The reader is referred to [SSH-GCM] for
 details on the format, initialization, and usage of these counters
 and their relationship to the initialization vector and the SSV.

6.2. Data Integrity

 The reader is reminded that, as specified in [SSH-GCM], Suite B
 requires that all 16 octets of the authentication tag MUST be used as
 the SSH data integrity value of the SSH binary packet.

7. Rekeying

 Secure Shell allows either the server or client to request that the
 Secure Shell connection be rekeyed.  Suite B places no constraints on
 how frequently this is to be done, but it does require that the
 cipher suite being employed MUST NOT be changed when a rekey occurs.

Igoe Informational [Page 12] RFC 6239 Suite B Crypto Suites for SSH May 2011

8. Security Considerations

 When using ecdh_sha2_nistp256, each exponent used in the key exchange
 must have 256 bits of entropy.  Similarly, when using
 ecdh_sha2_nistp384, each exponent used in the key exchange must have
 384 bits of entropy.  The security considerations of [SSH-Arch]
 apply.

9. References

9.1. Normative References

 [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
 [SUITEBCERT] Solinas, J. and L. Zieglar, "Suite B Certificate and
              Certificate Revocation List (CRL) Profile", RFC 5759,
              January 2010.
 [SSH-Arch]   Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Protocol Architecture", RFC 4251, January 2006.
 [SSH-Tran]   Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
              Transport Layer Protocol", RFC 4253, January 2006.
 [SSH-ECC]    Stebila, D. and J. Green, "Elliptic Curve Algorithm
              Integration in the Secure Shell Transport Layer", RFC
              5656, December 2009.
 [SSH-GCM]    Igoe, K. and J. Solinas, "AES Galois Counter Mode for
              the Secure Shell Transport Layer Protocol", RFC 5647,
              August 2009.
 [SSH-X509]   Igoe, K. and D. Stebila, "X.509v3 Certificates for
              Secure Shell Authentication", RFC 6187, March 2011.

9.2. Informative References

 [NIST]       National Institute of Standards and Technology, "Digital
              Signature Standard (DSS)", Federal Information
              Processing Standards Publication 186-3.
 [SEC1]       Standards for Efficient Cryptography Group, "Elliptic
              Curve Cryptography", SEC 1 v2.0, May 2009,
              <http://www.secg.org/download/aid-780/sec1-v2.pdf>.

Igoe Informational [Page 13] RFC 6239 Suite B Crypto Suites for SSH May 2011

 [SEC2]       Standards for Efficient Cryptography Group, "Recommended
              Elliptic Curve Domain Parameters", SEC 2 v1.0, September
              2000.  <http://www.secg.org/download/aid-386/
              sec2_final.pdf>.

Author's Address

 Kevin M. Igoe
 NSA/CSS Commercial Solutions Center
 National Security Agency
 EMail: kmigoe@nsa.gov

Igoe Informational [Page 14]

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