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rfc:rfc1898

Network Working Group D. Eastlake 3rd Request for Comments: 1898 CyberCash Category: Informational B. Boesch

                                                             CyberCash
                                                            S. Crocker
                                                             CyberCash
                                                              M. Yesil
                                                             CyberCash
                                                         February 1996
             CyberCash Credit Card Protocol Version 0.8

Status of this Memo

 This memo provides information for the Internet community.  This memo
 does not specify an Internet standard of any kind.  Distribution of
 this memo is unlimited.

Abstract

 CyberCash is developing a general payments system for use over the
 Internet.  The structure and communications protocols of version 0.8
 are described.  This version includes credit card payments only.
 Additional capabilities are planned for future versions.
 This document covers only the current CyberCash system which is one
 of the few operational systems in the rapidly evolving area of
 Internet payments. CyberCash is committed to the further development
 of its system and to cooperation with the Internet Engineering Task
 Force and other standards organizations.

Acknowledgements

 The significant contributions of the following persons (in alphabetic
 order) to this protocol are gratefully acknowledged:
      Bruce Binder, Judith Grass, Alden Hart, Steve Kiser, Steve
      Klebe, Garry Knox, Tom Lee, Bob Lindenberg, Jim Lum, Bill
      Melton, Denise Paredes, Prasad Chintamaneni, Fred Silverman,
      Bruce Wilson, Garland Wong, Wei Wu, Mark Zalewski.
 In addition, Jeff Stapleton and Peter Wagner made useful comments on
 the first version of this memo.

Eastlake, et al Informational [Page 1] RFC 1898 CyberCash Version 0.8 February 1996

History

 For historic purposes, it should be noted that this document was
 first posted as an Internet draft, and thus made publicly available,
 on 8 July 1995.

Table of Contents

    1. Overall System..........................................3
    1.1 System Overview........................................3
    1.2 Security Approach......................................5
    1.2.1 Authentication and Persona Identity..................5
    1.2.2 Privacy..............................................6
    1.3 Credit Card Operation..................................6
    2. General Message Wrapper Format..........................7
    2.1 Message Format.........................................7
    2.2 Details of Format......................................8
    2.3 Body Parts.............................................8
    2.4 Transparent Part.......................................9
    2.5 Opaque Part...........................................10
    2.6 Trailer...............................................10
    2.7 Example Messages......................................11
    3. Signatures and Hashes..................................12
    3.1 Digital Signatures....................................12
    3.2 Hash Codes............................................13
    4. Specific Message Formats...............................13
    4.1 Persona Registration and Application Retrieval........14
    4.1.1 R1 - registration...................................14
    4.1.2 R2 - registration-response..........................15
    4.1.3 GA1 - get-application...............................16
    4.1.4 GA2 - get-application-response......................17
    4.2 Binding Credit Cards..................................18
    4.2.1 BC1 - bind-credit-card..............................18
    4.2.2 BC4 - bind-credit-card-response.....................20
    4.3 Customer Credit Card Purchasing Messages..............21
    4.3.1 PR1 - payment-request...............................21
    4.3.2 CH1 - credit-card-payment...........................23
    4.3.3 CH2 - charge-card-response..........................24
    4.4 Merchant Credit Card Purchasing Messages..............25
    4.4.1 CM1 - auth-only.....................................26
    4.4.2 CM2 - auth-capture..................................28
    3.4.3 CM3 - post-auth-capture.............................28
    4.4.4 CM4 - void..........................................30
    4.4.5 CM5 - return........................................32
    4.4.6 CM6 - charge-action-response........................32
    4.4.7 The MM* Message Series..............................34
    4.4.8 CD1 - card-data-request.............................35
    4.4.9 CD2 - card-data-response............................37

Eastlake, et al Informational [Page 2] RFC 1898 CyberCash Version 0.8 February 1996

    4.5 Utility and Error Messges.............................38
    4.5.1 P1 - ping...........................................39
    4.5.2 P2 - ping-response..................................39
    4.5.3 TQ1 - transaction-query.............................40
    4.5.4 TQ2 - transaction-cancel............................41
    4.5.5 TQ3 - transaction-response..........................42
    4.5.6 UNK1 - unknown-error................................44
    4.5.7 DL1 - diagnostic-log................................46
    4.5.8 DL2 - merchant-diagnostic-log.......................47
    4.6 Table of Messages Described...........................48
    5. Future Development.....................................49
    5.1 The Credit Card Authorization/Clearance Process.......49
    5.2 Lessons Learned.......................................50
    6. Security Considerations................................51
    References................................................51
    Authors' Addresses........................................52

1. Overall System

 CyberCash, Inc. of Reston, Virginia was founded in August of 1994 to
 partner with financial institutions and providers of goods and
 services to deliver a safe, convenient and inexpensive system for
 making payments on the Internet.  The CyberCash approach is based on
 establishing a trusted link between the new world of cyberspace and
 the traditional banking world.  CyberCash serves as a conduit through
 which payments can be transported quickly, easily and safely between
 buyers, sellers and their banks.  Significantly - much as it is the
 real world of commerce - the buyer and seller need not have any prior
 existing relationship.
 As a neutral third party whose sole concern is ensuring the delivery
 of payments from one party to another, CyberCash is the linchpin in
 delivering spontaneous consumer electronic commerce on the Internet.

1.1 System Overview

 The CyberCash system will provide several separate payment services
 on the Internet including credit card and electronic cash.  To gain
 access to CyberCash services, consumers need only a personal computer
 with a network connection.  Similarly, merchants and banks need make
 only minimal changes to their current operating procedures in order
 to process CyberCash transactions, enabling them to more quickly
 integrate safe on-line payments into their existing service
 offerings.  Communications with banks are over existing financial
 communications networks.

Eastlake, et al Informational [Page 3] RFC 1898 CyberCash Version 0.8 February 1996

 To get started, consumers download free software from CyberCash on
 the Internet.  This software establishes the electronic link between
 consumers, merchants and their banks as well as between individuals.
 To make gaining access to the CyberCash system even easier, CyberCash
 "PAY" buttons may be incorporated into popular on-line service and
 software graphical user interfaces so that consumers using these
 products can easily enter the CyberCash system when they are ready to
 make payments for goods and services.  Consumers need not have any
 prior relationship with CyberCash to use the CyberCash system.  They
 can easily set up their CyberCash persona on-line.
 Transactions are automated in that once the consumer enters
 appropriate information into his own computer, no manual steps are
 required to process authorization or clearance transactions through
 the entire system.  The consumer need only initiate payment for each
 transaction by exercising the pay option on an electronic form.
 Transactions are safe in that they are cryptographicly protected from
 tampering and modification by eavesdroppers. And they are private in
 that information about the consumer not relevant to the transaction
 is not visible to the merchant.
    +------------+            +------------+
    |            |            |            |
    |  Internet  |            |  Internet  |
    |  customer  +------------+  merchant  +
    |            |            |  /         |
    +------------+            +------------+
                              /
                             /
                 +------------|-+
                 | CyberCash  | |
                 |     server | |
                 +-----+------|-+
                       |      |
                       |      |
        +--------------+------|---------+
        | +--------+       +--+-------+ |
        | | card   +-------+ / charge | |
        | | issuer |       | acquirer | |
        | +--------+       +----------+ |
        |                               |
        |      The Banking System       |
        +-------------------------------+
                 SYSTEM OVERVIEW

Eastlake, et al Informational [Page 4] RFC 1898 CyberCash Version 0.8 February 1996

1.2 Security Approach

 The CyberCash system pays special attention to security issues.  It
 uses encryption technology from the world's leading sources of
 security technology and is committed over time to employing new
 security technologies as they emerge.

1.2.1 Authentication and Persona Identity

 Authentication of messages is based on Public Key encryption as
 developed by RSA.  The CyberCash Server maintains records of the
 public key associated with every customer and merchant persona.  It
 is thus able to authenticate any information digitally signed by a
 customer or merchant regardless of the path the data followed on its
 way to the server.  The corresponding private key, which is needed to
 create such digital signatures, will be held by the customer or
 merchant and never revealed to other parties.  In customer software,
 the private key is only stored in an encrypted form protected by a
 passphrase.
 While the true CyberCash identity of a customer or merchant is
 recognized by their public/private key pair, such keys are too
 cumbersome (over 100 hex digits) to be remembered or typed by people.
 So, the user interface utilizes short alphanumeric ID's selected by
 the user or merchant for purposes of specifying a persona.  CyberCash
 adds check digits to the requested ID to minimize the chance of
 accidental wrong persona selection.  Persona IDUs are essentially
 public information.  Possession of an persona ID without the
 corresponding private key is of no benefit in the current system.
 Individuals or organizations may establish one or more CyberCash
 customer personas directly with CyberCash.  Thus, an individual may
 have several unrelated CyberCash personas or share a CyberCash
 persona with other individuals.  This approach provides a degree of
 privacy consistent with Internet presence generally and with cash
 transactions specifically.  However, persona holders who wish to use
 a credit card for purchases in conjunction with their CyberCash
 persona must first meet such on-line identification criteria as the
 card issuing organization requires.
 Control over a CyberCash persona is normally available only to an
 entity that possesses the private key for that persona.  However, a
 special provision is made to associate an emergency close out
 passphrase with a CyberCash persona.  On receipt of the emergency
 close out passphrase, even if received over insecure channels such as
 a telephone call or ordinary email, CyberCash will suspend activity
 for the CyberCash persona.  This emergency close-out passphrase can
 be stored separately from and with somewhat less security than the

Eastlake, et al Informational [Page 5] RFC 1898 CyberCash Version 0.8 February 1996

 private key for the persona since the emergency passphrase can not be
 used to divert funds to others. This provides some protection against
 loss or misappropriation of the private key or the passphrase under
 which the private key in kept encrypted.  In the cash system, the
 emergency close-out passpharase may also transfer the persona balance
 to a designated bank account.

1.2.2 Privacy

 Encryption of messages use the Digital Encryption Standard (DES),
 commonly used in electronic payment systems today.  It is planned to
 superencrypt (i.e., encrypted more than one level) particularly
 sensitive information, such as PIN numbers, and handle them so that
 the plain text readable version never exists in the CyberCash system
 except momentarily, within special purpose secure cryptographic
 hardware that is part of the server, before being re-encrypted under
 another key.
 The processing of card charges through the CyberCash system is
 organized so that the merchant never learns the customerUs credit
 card number unless the merchantUs bank chooses to release this
 information to the merchant or it is required for dispute resolution.
 In addition, the server maintains no permanent storage of card
 numbers.  They are only present while a transaction involving that
 card is in progress.  These practices greatly reduce the chance of
 card number misappropriation.

1.3 Credit Card Operation

 Using the CyberCash system for credit card transactions, once price
 has been negotiated and the consumer is ready to purchase, the
 consumer simply clicks on the CyberCash "PAY" button displayed on the
 merchant interface, which invokes the merchant CyberCash software.
 The merchant sends the consumer an on-line invoice that includes
 relevant purchase information which appears on the customerUs screen.
 (See PR1 message.)  The consumer adds his credit card number and
 other information by simply selecting from a list of credit cards he
 has registered to his CyberCash persona.  All this information is
 digitally signed by the customer's CyberCash software, encrypted, and
 passed, along with a hash code of the invoice as seen by the
 customer, to the merchant.  (See CH1 message.)
 Upon receipt, the merchant adds additional authorization information
 which is then encrypted, electronically signed by the merchant, and
 sent to the CyberCash Server.  (See CM1 & CM2 messages.)  The
 CyberCash Server can authenticate all the signatures and be sure that
 the customer and merchant agree on the invoice and charge amount.
 The CyberCash Server then forwards the relevant information to the

Eastlake, et al Informational [Page 6] RFC 1898 CyberCash Version 0.8 February 1996

 acquiring bank along with a request on behalf of the merchant for a
 specific banking operation such as charge authorization.  The bank
 decrypts and then processes the received data as it would normally
 process a credit card transaction.  The bank's response is returned
 to the CyberCash Server which returns an electronic receipt to the
 merchant (see CM6 message) part of which the merchant is expected to
 forward to the customer (see CH2 message).  The transaction is
 complete.

2. General Message Wrapper Format

 Version 0.8 of the external format for the encoding of CyberCash
 messages is described below.  CyberCash messages are stylized
 documents for the transmission of financial data over the Internet.
 While there are numerous schemes for sending information over the
 Internet (HTTP, SMTP, and others), each is attached to a specific
 transmission mechanism.  Because CyberCash messages will need to
 travel over each of these media (as well as others) a transmission
 independent mechanism is needed.

2.1 Message Format

 CyberCash messages consist of the following components:
 1. Header - defines the start of the CyberCash message and includes
    version information.
 2. Transparent Part - contains information that is not private.
 3. Opaque Part(s) - contains the financial information in the
    message and is both privacy protected as well as tamper protected.
    An opaque part is not present in some messages. When present, the
    opaque part usually provides tamper protection for the transparent
    part.
 4. Trailer - defines the end of the CyberCash message and includes a
    check value to enable the receiver to determine that the message
    has arrived undamaged. Note: this check value is intended only to
    detect accidental damage to the message, not deliberate tampering.
    No null characters (zero value) or characters with the eighth bit
    on are permitted inside a CyberCash message.  "Binary" quantities
    that might have such byte values in them are encoded in base64 as
    described in RFC 1521.

Eastlake, et al Informational [Page 7] RFC 1898 CyberCash Version 0.8 February 1996

2.2 Details of Format

 The header consists of a single line which looks approximately like
 this
      $$-CyberCash-0.8-$$
 or like this
      $$-CyberCash-1.2.3-Extra-$$
 It includes a number of fields separated with the minus character "-"
 1. "$$" - the literal string with the initial $ in column 1.
 2. "CyberCash" - the literal string (case insensitive)
 3. x.y or x.y.z - the version number of the message format.  x is the
 primary version number.  y is a subversion number.  z, if present, is
 a subsubversion number.
 4. "Extra" - an optional additional alphanumeric string.
 5.  "$$" - the literal string
 Version numbers start at 0.7 and count up.  The ".z" is omitted when
 z is zero.  0.7 and 0.8 are the test and initial shipped version of
 the credit card system. 0.9 and 1.0 are expected to also incorporate
 the test and initial shipped versions of the cash facilities as well
 as improvements to the credit card system.
 The "Extra" string is used within secure environments so that one
 subcomponent can scribble a note to another with minimum overhead.
 For example, a server firewall could put "HTTP" or "SMTP" here before
 forwarding the message to the core server within the firewall
 perimeter.

2.3 Body Parts

 The body parts of the message (both transparent and opaque) consist
 of attribute value pairs in formats that are reminiscent of the
 standard electronic mail header (RFC822) format. However, there are
 some differences.
 Attribute names start with and are composed predominantly of letters
 and internal hyphens except that they sometimes end with a hyphen
 followed by a number.  Such a trailing number is used when there is
 logically an indexed vector of values.  Attribute names are

Eastlake, et al Informational [Page 8] RFC 1898 CyberCash Version 0.8 February 1996

 frequently referred to as labels.
 If the label ends with a ":", then RFC822 processing is done.  While
 the existence of trailing white space is significant, all leading
 white space on continuation lines is stripped.  Such lines are
 wrapped at 64 characters in length, excluding any line termination
 character(s).
 However, if the label is terminated with a ";", this indicates a
 free-form field where new-line characters and any leading white
 space, after the initial space that indicates a continuation line, is
 significant.  Such lines should not be wrapped except that, to avoid
 other processing problems, they are forcibly wrapped at 200
 characters.
 Blank lines are ignored and do not signify a change  to  a  different
 mode of line handling.
 Another way of looking at the above is as follows: after having found
 an initial $$ start line, you can treat any following lines according
 to the first character.  If it is alphanumeric, it is a new label
 which should be terminated with a ":" or ";" and indicates a new
 label-value pair.  If it is a white space character, it indicates the
 continuation of the value for the preceding new label line.  (Exactly
 how the continuation is processed depends on the label termination
 character.)  If it is "$", it should be the end line for the message.
 If it is #, it is a comment line and should be ignored.  Other
 initial characters are undefined.  (As of this date, no software
 sends CyberCash messages with # lines but they are convenient for
 commenting messages stored in files.)

2.4 Transparent Part

 The transparent part includes any clear-text data associated with the
 financial transaction as well as information needed by CyberCash and
 others to decrypt the opaque part(s).  It always includes a
 transaction field which is the transaction number generated by the
 requester and which is repeated in the response.  It always includes
 a date field that is the local date and time at the requester and is
 repeated in the response.  In all cases other than an initial
 registration to establish a persona ID, it includes the requester's
 persona ID.
 On messages bound for the server, there is a "cyberkey:" field that
 identifies which server public key was used to encrypt the session
 key.

Eastlake, et al Informational [Page 9] RFC 1898 CyberCash Version 0.8 February 1996

2.5 Opaque Part

 The opaque part consists of a single block of characters encoded
 using base64 encoding (see RFC 1521). The data in the opaque section
 is always encrypted before encoding.
 The label "opaque" or "merchant-opaque" precedes the opaque part
 depending on whether the data was encrypted by the client or merchant
 software.
 On messages inbound to the server, the data to be opaqued is DES CBC
 encrypted under a random transacton key and then that DES key is RSA
 encrypted under one of the server's public keys.  The RSA encrypted
 DES key appears as the first part of the base64 encoded field and is
 not broken out as a separate value in the message.  The corresponding
 outbound reply from the server can simply be DES encrypted under this
 transaction key as there is enough plain text information to identify
 the transaction and the customer or merchant will have remembered the
 transaction key from the inbound message.
 A signature is not generally necessary in the opaque part of a reply
 message.  Knowledge of the transaction key is adequate
 authentication.  In order for someone to forge the response, they
 would have to know the server's private key to be able to get at the
 transaction key.  It is assumed that if anyone tampered with the
 response opaque part, the probability that it would decrypt to
 something that would parse is insignificant.  (Just the fact that the
 8th bit has to be off means a chance of 1 in 2**n where there are n
 characters and that's ignoring the rest of the formatting.)  While
 someone can tamper with the transparent part, this usually either has
 no effect or means that the client won't find the transaction key, in
 which case it's just a particular example of denial of service by
 damaging a message.

2.6 Trailer

 The trailer is intended to close the message and provide a definitive
 and parseable end of the message.
 The trailer consists of several fields separated by "-" as in header.
 1. "$$" - literal string.
 2. "CyberCash" - literal string (case insensitive).
 3. "End" - literal string (case insensitive).
 4. transmission checksum.

Eastlake, et al Informational [Page 10] RFC 1898 CyberCash Version 0.8 February 1996

 5.  "$$" - literal string.
 The transmission checksum is the MD5 has of all printable characters
 in the version number in the start line and those appearing after the
 second $$ of the start line and before the first $$ of the trailer
 line as transmitted.  Note that all white space is left out of this
 hash, including any new-lines, spaces, tabs, carriage returns, etc.
 The exact label terminators actually used (: or ;) are included as
 would any # comment line.  Note that the optional "Extra" string in
 the $ start line is not included.  The idea is to check correct
 transmission while avoiding sensitivity to gateways or processing
 that might change the line terminator sequence, convert tabs to
 spaces, or the like.

2.7 Example Messages

 Simple message from a client:
 $$-CyberCash-0.8-$$
 id: DONALD-69
 transaction: 918273645
 date: 199512250102
 cyberkey:CC1001
 opaque:
  GpOJvDpLH62z+eZlbVkhZJXtTneZH32Qj4T4IwJqv6kjAeMRZw6nR4f0OhvbTFfPm+GG
  aXmoxyUlwVnFkYcOyTbSOidqrwOjnAwLEVGJ/wa4ciKKI2PsNPA4sThpV2leFp2Vmkm4
  elmZdS0Qe350g6OPrkC7TKpqQKHjzczRRytWbFvE+zSi44wMF/ngzmiVsUCW01FXc8T9
  EB8KjHEzVSRfZDn+lP/c1nTLTwPrQ0DYiN1lGy9nwM1ImXifijHR19LZIHlRXy8=
 $$-End-CyberCash-End-jkn38fD3+/DFDF3434mn10==-$$
 Message from a merchant:
 $$-CyberCash-a.b.c-extra-$$
 merchant-ccid: acme-69
 merchant-date: 19951231115959
 merchant-transaction: 987654321
 label: value
 labelx: multiple line
    value...
 # comment
 # another comment line
 label; text with a real
   multi-line
      format !
 merchant-cyberkey: CC1001
 merchant-opaque:

Eastlake, et al Informational [Page 11] RFC 1898 CyberCash Version 0.8 February 1996

  C1Q96lU7n9snKN5nv+1SWpDZumJPJY+QNXGAm3SPgB/dlXlTDHwYJ4HDWKZMat+VIJ8y
  /iomz6/+LgX+Dn0smoAge7W+ESJ6d6Ge3kRAQKVCSpbOVLXF6E7mshlyXgQYmtwIVN2J
  66fJMQpo31ErrdPVdtq6MufynN8rJyJtu8xSNolXlqIYNQy5G2I3XCc6D3UnSErPx1VJ
  6cbwjLuIHHv58Nk+xxt/FyW7yAMwUb9YNcmOj//6Ru0NiOA9P/IiWczDe2mJRK1uqVpC
  sDrWehG/UbFTPD26trlYRnnY
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$

3. Signatures and Hashes

 Inbound CyberCash request messages normally have a signature, as
 described below, of all of the messages fields outside of the
 signature.  This signature is transmitted inside the opaque part of
 the message.  It enables the server to authenticate the source of the
 message.
 Messages from a merchant to a client initiating a purchase sequence
 have fields signed by the merchant.  These fields and this signature
 are included by the client in the opaque part of their card purchase
 message to the merchant so that, when all is passed on to the server,
 it can verify that the client saw the information the merchant
 intended.
 More information on CyberCash signatures and the hash codes they are
 based on, is given below.

3.1 Digital Signatures

 Digital signatures are a means of authenticating information.  In
 CyberCash messages, they are calculated by first taking the hash of
 the data to be authenticated, as described below, and then encoding
 the hash using an RSA private key.
 Anyone possessing the corresponding public key can then decrypt the
 hash and compare it with the message hash.  If they match, then you
 can be sure that the signature was generated by someone possessing
 the private key which corresponded with the public key you used and
 that the message was not tampered with.
 In the CyberCash system, clients, merchants, and the server have
 public-private key pairs.  By keeping the private key secret and
 registering their public key with the server (for a merchant or
 client) or publishing their public key or keys (for the server), they
 can provide high quality authentication by signing parts of messages.
 An RSA digital signature is approximately the size of the modulus
 used.  For example, if that is 768 bits long, then the binary digital
 signature would be 768 bits or 96 bytes long and its base 64 encoding
 would be 128 bytes.

Eastlake, et al Informational [Page 12] RFC 1898 CyberCash Version 0.8 February 1996

3.2 Hash Codes

 The hashes used in CyberCash messages are message digests.  That is,
 a non-invertable fingerprint of a message such that it is
 computationally infeasible to find an alternate message with the same
 hash.  Thus the relatively small hash can be used to secure a larger
 message.  If you are confident in the authenticity of the hash and
 are presented with a message which matches the hash, you can be sure
 it is the original message, at least as regards all aspects that have
 been included in the hash.
 The hash is calculated using the MD5 algorithm (see RFC 1321) on a
 synthetic message.  The synthetic message is composed of the labels
 and values specified in a list for the particular hash.  Since the
 hash is input order dependent, it is essential that the label-value
 pairs be assembled in the order specified.  In some cases, a range of
 matching labels is specified.  For example, "card*" to match card-
 number, card-expiration-date, and all other labels starting with
 "card".  In such cases, all existing matching labels are used in
 ascending alphabetic order by ASCII character code.
 If a label is specified in a signature list but is not present in the
 label-value data on which the hash is being calculated, it is not
 included in the hash at all.  That is, even the label and label
 terminator are omitted from the synthetic message.
 Before being hashed, the text of the synthetic message is processed
 to remove all "white space" characters.  White space characters are
 defined as any with an ASCII value of 32 (space) or less or 127
 (rubout) or greater.  Thus all forms of new-line/carriage-return and
 distinctions such as blank lines, trailing spaces, replacement of a
 horizontal tab character by multiple spaces, etc., are ignored for
 hash purposes.
 MD5 hashes are 16 bytes long.  This means that the base 64 encoding
 of such a hash will be 24 characters (of which the last two will
 always be padding equal signs).

4. Specific Message Formats

 This section describes the formats of the Verison 0.8 CyberCash
 messages by example with comments.  The reader in assumed to be
 familiar with terms such as "acquirer", "PAN" (primary account
 number), etc., defined in ISO 8583, and currency designations as
 defined in ISO 4217. A few fields not relevant to current operations
 have been removed to simplify this exposition.

Eastlake, et al Informational [Page 13] RFC 1898 CyberCash Version 0.8 February 1996

 In the following example messages, signatures, hashes, and encrypted
 sections are fake nonsense text and ids are fictitious.

4.1 Persona Registration and Application Retrieval

 The first step in customer use of CyberCash is registering a persona
 using the customer application.  This is done with the R1 message
 defined below.  The CyberCash server responds with the R2 message.
 When the customer application learns that it is out of date, it can
 use the GA1 request message to the server and its GA2 response to
 download a new signed version of itself.

4.1.1 R1 - registration

 Description: This is the initial message sent to create a new
     CyberCash persona.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 transaction: 123123213
 date: 19950121100505.nnn
 cyberkey: CC1001
 opaque:
  FrYOQrD16lEfrvkrqGWkajM1IZOsLbcouB43A4HzIpV3/EBQM5WzkRJGzYPM1r3noBUc
  MJ4zvpG0xlroY1de6DccwO9j/0aAZgDi9bcQWV4PFLjsN604j3qxWdYn9evIGQGbqGjF
  vn1qI1Ckrz/4/eT1oRkBBILbrWsuwTltFd84plvTy+bo5WE3WnhVKsCUJAlkKpXMaX73
  JRPoOEVQ3YEmhmD8itutafqvC90atX7ErkfUGDNqcB9iViRQ7HSvGDnKwaihRyfirkgN
  +lhOg6xSEw2AmYlNiFL5d/Us9eNG8cZM5peTow==
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: Generated using CyberCash encrypting public key
     identified in CyberKey.
 #####################################################################
 Opaque Section Contents:
 type: registration
 swversion: 0.8win
 content-language: en-us
 requested-id: MyRequestedCCID

Eastlake, et al Informational [Page 14] RFC 1898 CyberCash Version 0.8 February 1996

 email: myemail@myemailhost.com
 pubkey:
  0VdP1eAUZRrqt3Rlg460Go/TTs4gZYZ+mvI7OlS3l08BVeoms8nELqL1RG1pVYdDrTsX
  E5L+wcGCLEo5+XU5zTKkdRUnGRW4ratrqtcte7e94F+4gkCN06GlzM/Hux94
 signature:
  v6JGmxIwRiB6iXUK7XAIiHZRQsZwkbLV0L0OpVEvan9l59hVJ3nia/cZc/r5arkLIYEU
  dw6Uj/R4Z7ZdqO/fZZHldpd9+XPaqNHw/y8Arih6VbwrO5pKerLQfuuPbIom
 #####################################################################
 signature is of the following fields: transaction, date, cyberkey,
     type, swversion, content-language, requested-id, email, pubkey
 #####################################################################
 Explanation:
 content-language is taken from the MIME header field (see RFC1766)
     and is the language text messages should be generated in.  (only
     en-us implemented at this time.
 swversion used to check if client application is old.

4.1.2 R2 - registration-response

 Description: This message gives the success/failure response to R1.
 #####################################################################
 Sender: CyberServer
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 transaction: 12312313
 date: 19950121100505.nnn
 opaque:
  r1XfjSQt+KJYUVOGU60r7voFrm55A8fP5DjJZuPzWdPQjGBIu3B6Geya8AlJfHsW11u8
  dIv1yQeeYj/+l9TD1dXW21/1cUDFFK++J2gUMVv8mX1Z6Mi4OU8AfsgoCliwSkWmjSOb
  kE62sAlZTnw998cKzMFp70TSlI3PEBtvIfpLq5lDCNbWidX8vFZV0ENUmMQ9DTP3du9w
  fsFGvz1mvtHLT/Gj8GNQRYKF4xiyx4HYzTkSMhgU5B/QDLPS/SawIJuR86b9X0mwsr0a
  gbGTzECPJTiKkrhxxMG/eymptsVQSLqNaTCx6w==
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: Same as session key for R1 for same Transaction and
     connection (there may be no ID!).
 #####################################################################
 Opaque Section Contents:

Eastlake, et al Informational [Page 15] RFC 1898 CyberCash Version 0.8 February 1996

 type: registration-response
 server-date: 19950121100506.nnn
 requested-id: MyRequestedCCID
 response-id: CyberCashHandle
 email: myemail@myemailhost.com
 response-code: success/failure/etc.
 pubkey:
  0VdP1eAUZRrqt3Rlg460Go/TTs4gZYZ+mvI7OlS3l08BVeoms8nELqL1RG1pVYdDrTsX
  E5L+wcGCLEo5+XU5zTKkdRUnGRW4ratrqtcte7e94F+4gkCN06GlzM/Hux94
 swseverity: fatal/warning  [absent if ok]
 swmessage; Tells CyberApp that it is obsolete.  Display this
  text to the user.  [only present if SWSeverity present]
 message;
        Free text of the error/success condition.
        This text is to be displayed to the person
        by the CyberCash application...
        In general this includes: duplicate-id, bad-signature,
        or ill-formed-registration
 #####################################################################
 Signature is of the following fields: no-signature
 #####################################################################
 Explanation:
 responseid is used to suggest a unique ID if the failure was due
     to the requested ID being already in use... If the reason for
     failure was not due to duplicate ID then this field may be
     omitted.
 responseid gives the actual ID with check characters appended if
     success.
 swseverity can warn user of old client application or indicate
     failure due to old or known buggy version.

4.1.3 GA1 - get-application

 Description: Used by CyberApp to get an updated version.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 transaction: 123123213
 date: 19950121100505.nnn

Eastlake, et al Informational [Page 16] RFC 1898 CyberCash Version 0.8 February 1996

 cyberkey: CC1001
 opaque:
  VHMS611wGkUmR6bKoI+ODoSbl7L5PKtEo6aM88LCidqN+H/8B4xM3LxdwUiLn7rMPkZi
  xOGb+5d1lRV7WeTp21QYlqJr8emc6FAnGd5c0csPmcnEpTFh9xZDJaStarxxmSEwm2mw
  l2VjEUODH6321vjoMAOFQWn7ER0o
 $$-CyberCash-End-0QXqLlNxrn4GNQPPk9AO1Q==-$$
 #####################################################################
 Opaque Key: Generated using CyberCash encrypting public key identified
    in CyberKey.
 #####################################################################
 Opaque Section Contents:
 type: get-application
 swversion: 0.8win
 #####################################################################
 Signature is of the following fields: no signature
 #####################################################################
 Explanation:
 There may not be a customer persona so there is no ID.  There
     may not be a customer public/private key pair so there is
     no signature.  The swversion is mandatory so the server can
     tell what to return.

4.1.4 GA2 - get-application-response

 Description: Return success and URL of up to date copy of CyberApp
     or failure.
 #####################################################################
 Sender: CyberServer
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 transaction: 12312313
 date: 19950110102333.nnn
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==

Eastlake, et al Informational [Page 17] RFC 1898 CyberCash Version 0.8 February 1996

 $$-CyberCash-End-0QXqLlNxrn4GNQPPk9AO1Q==-$$
 #####################################################################
 Opaque Key: session key from GA1
 #####################################################################
 Opaque Section Contents:
 type: get-application-response
 server-date: 19950110102334.nnn
 response-code: success/failure/etc.
 message; Text message to be displayed to the user providing more
     information on the success/failure.
 swversion: 0.8win
 application-url: http://foo.cybercash.com/server/0.8WIN.EXE
 application-hash: lSLzs/vFQ0BXfU98LZNWhQ==
 #####################################################################
 Signature: none.
 #####################################################################
 Explanation:
 application-hash is the MD5 of the binary of the application.
 application-url & application-hash omitted on failure.
 swversion is the version being transmitted to the customer.

4.2 Binding Credit Cards

 The CyberCash system is design to give the card issuing organization
 control over whether a card may be used via the CyberCash system.
 The customer, after having registered a persona with CyberCash as
 described above, can then bind each credit card they wish to use to
 their CyberCash persona.  This is done via the BC1 message from the
 customer to their CyberCash server and the BC4 response from the
 server.

4.2.1 BC1 - bind-credit-card

 Description: This is the initial message in the process of binding a
     credit card to a CyberCash persona.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:

Eastlake, et al Informational [Page 18] RFC 1898 CyberCash Version 0.8 February 1996

 $$-CyberCash-0.8-$$
 id: MyCyberCashID
 date: 19950121100505.nnn
 transaction: 12312314
 cyberkey: CC1001
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: generated from CyberCash encryption key identified in
     CyberKey
 #####################################################################
 Opaque Section Contents:
 type: bind-credit-card
 swversion: 0.8win
 card-number: 1234567887654321
 card-type: mastercard
 card-salt: 46735210
 card-expiration-date: 05/99
 card-name: John Q. Public
 card-street:
 card-city:
 card-state:
 card-postal-code:
 card-country:
 signature:
  tX3odBF2xPHqvhN4KVQZZBIXDveNi0eWA7717DNfcyqh2TpXqgCxlDjcKqdJXgsNLkY7
  GkyuDyTF/m3SZif64giCLjJRKg0I6mqI1k/Dcm58D9hKCUttz4rFWRqhlFaj
 #####################################################################
 signature is of the following fields: id, date, transaction,
     cyberkey, type, swversion, card-number, card-salt,
     card-expiration-date, card-name, card-street, card-city,
     card-state, card-postal-code, card-country
 #####################################################################
 Explanation:
 salt is needed so that the hash stored at the server is less
     informative.  Server just remembers the "prefix" of the card
     number and the hash of the combined card number and salt. If it
     just hashed the card number, it would be recoverable with modest

Eastlake, et al Informational [Page 19] RFC 1898 CyberCash Version 0.8 February 1996

     effort by trying to hash all plausible numbers.  We don't want
     to store the card numbers on the server because it would make
     the server files too valuable to bad guys.

4.2.2 BC4 - bind-credit-card-response

 Description: Indicates that the process of binding a credit card
     terminated.  Returns success or failure.
 #####################################################################
 Sender: CyberServer
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 id: mycybercashid
 transaction: 12312314
 date: 19950121100505.nnn
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: Session key from BC1 with same Transaction and ID
 #####################################################################
 Opaque Section Contents:
 type: bind-credit-card-response
 server-date: 19950121100506.nnn
 swseverity: fatal/warning  [absent if ok]
 swmessage; message about obsoleteness of customer software
     to be shown to the customer.  [only present if SWSeverity present]
 response-code: success/failure/etc.
 card-number: 1234567887654321
 card-type: visa
 card-salt: 47562310
 card-expiration-date: 01/99
 card*: [other card* lines to also be given in CH.1 message]
 message; Plain text for the user
     can be multiple lines

Eastlake, et al Informational [Page 20] RFC 1898 CyberCash Version 0.8 February 1996

 #####################################################################
 Signature is of the following fields: no-signature
 #####################################################################
 Explanation: All the card* lines can be saved as a blob to be
     submitted in CH.1.  card-expiration-date, card-number, card-salt,
     and card-type should always be present.
 Depending on reason for failure, not all fields may be present.

4.3 Customer Credit Card Purchasing Messages

 In general, CyberCash involvement in the credit card purchasing cycle
 starts after the user has determined what they are buying.  When they
 click on the CyberCash payment button, a PR1 message is sent by the
 merchant to the customer as the body of a message of MIME type
 application/cybercash.
 If the customer wishes to proceed, they respond to the merchant  with
 a  CH1.   The merchant responds with a CH2 but between the receipt of
 the CH1 and issuance of the CH2, the  merchant  usually  communicates
 with the CyberCash server via the CM* messages.

4.3.1 PR1 - payment-request

 Description: This message is the first message that is defined
     by CyberCash in the purchase-from-a-merchant process. The
     shopping has completed.  Now we are at the point of paying
     for the purchases.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 type: payment-request
 merchant-ccid: ACME-012
 merchant-order-id: 1231-3424-234242
 merchant-date: 19950121100505.nnn
 note;
   ACME Products
   Purchase of 4 pairs "Rocket Shoes" at $39.95 ea.
   Shipping and handling $5.00

Eastlake, et al Informational [Page 21] RFC 1898 CyberCash Version 0.8 February 1996

   Total Price: 164.80
   Ship to:
        Wily Coyote
        1234 South St.
        Somewhere, VA 12345
 merchant-amount: usd 164.80
 accepts: visa:CC001, master:CC001,amex:CC001,JCPenny:VK005,macy:VK006
 url-pay-to: http://www.ACME.com/CybercashPayment
 url-success: http://www.ACME.com/ordersuccess
 url-fail: http://www.ACME.com/orderfail
 merchant-signed-hash:
  a/0meaMHRinNVd8nq/fKsYg5AfTZZUCX0S3gkjAhZTmcrkp6RZvppmDd/P7lboFLFDBh
  Ec0oIyxWeHfArb3OtkgXxJ7qe0Gmm/87jG5ClGnpBnw0dY7qcJ6XoGB6WGnD
 $$-CyberCash-End-lSLzs/vFQ0BXfU98LZNWhQ==-$$
 #####################################################################
 Opaque Key: no opaque section
 #####################################################################
 Opaque Section Contents: no opaque section
 #####################################################################
 merchant-signed-hash is the signature under the merchant's
     private key of the hash of the following fields: type,
     merchant-ccid, merchant-order-id, date, note, merchant-amount,
     accepts, url-pay-to, url-success, url-fail
 #####################################################################
 Explanation:
 This message is signed by the merchant but the customer cannot
     directly verify this signature. When the payment is made, the
     Customer includes the signature with the hash (derived by the
     customer directly) in the payment. If these do not match, the
     CyberCash will not perform the payment function.
 accepts: The client software will only recognized single word card
 name in the accepts field of PR1. For example,
   MasterCard
   AmericanExpress
 are recognized where as
   Master card
   American express
 are not recognized. MasterCard and masterCard are both
 recognized as master card.
 Card type followed by key designator.  For main line credit cards,
     this will be a CC*.  Client can use or ignore the * number as
     it chooses.  For proprietary card, this will be VK* where * is
     the CheckFree key to use (1 based).  Cards separated by comma,

Eastlake, et al Informational [Page 22] RFC 1898 CyberCash Version 0.8 February 1996

     key designator follows card type and colon.
 url-pay-to is where the CH1 should be sent.  url-fail and url-success
     are where the browser should look after failure or success.

4.3.2 CH1 - credit-card-payment

 Description: This message represents the presentation of a "credit
     card for payment".
 #####################################################################
 Sender: CyberApp
 Receiver: MerchantApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 type: card-payment
 id: myCyberCashID
 order-id: 1231-3424-234242
 merchant-ccid: ACME-012
 transaction: 78784567
 date: 19950121100505.nnn
 pr-hash: c77VU/1umPKH2kpMR2QVKg==
 pr-signed-hash:
  a/0meaMHRinNVd8nq/fKsYg5AfTZZUCX0S3gkjAhZTmcrkp6RZvppmDd/P7lboFLFDBh
  Ec0oIyxWeHfArb3OtkgXxJ7qe0Gmm/87jG5ClGnpBnw0dY7qcJ6XoGB6WGnD
 cyberkey: CC1001
 opaque:
  iff/tPf99+Tm5P7s3d61jOWK94nq9/+1jOWK9+vr9+b+94n3tYzmiveJ9/+09/334ubg
  3rWM5Ir3ier3/7WM5Ir36+v35v73ife1jOWK94n3/7T3/ffm5uD+7N339/f39/eq3ff3
  9/eFiJK5tLizsoeSmpW7uLS8/7iio7Wisfv38biio7uyufv3tfv35uH+7N3d9/exuKX3
  5+z3vuu4oqO7srnsvvz8/venoqO0v7al/7iio7WisYy+iv7s3ff3p6KjtL+2pf/wi7nw
  3ard3Q==
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Opaque Key: Created using CyberCash encrypting public key in
     CyberKey.
 #####################################################################
 Opaque Section Contents:
 swversion: 0.8win
 amount: usd 10.00
 card*: [from successful BC4 (includes card-expiration-date,
     card-number, card-type, and card-salt)]
 signature:
  meO38aULnoP09VhTS2E56tnuZBRRlGfbwqaleZ9zNnv7YjExJKBFxuaqYTUDEj427HHh

Eastlake, et al Informational [Page 23] RFC 1898 CyberCash Version 0.8 February 1996

  mm9BVmHRwCq6+8ylZXixGHI1I9A/ufAMrpqMIi6DS3PRlc8WC3CCWoAHyAqr
 #####################################################################
 signature is under client private key of the following fields:
     type, id, order-id, merchant-ccid, transaction, date,
     pr-hash, pr-signed-hash, cyberkey, swversion, amount,
     card*
 #####################################################################
 Explanation:
 The pr-signed-hash field is the same as the merchant-signed-hash in
     the PR1 message but has a different name for historic reasons.

4.3.3 CH2 - charge-card-response

 Description: Return to customer from a CH1 attempt to pay via credit
     card.  Indicates success/failure.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 type: charge-card-response
 merchant-ccid: ACME-012
 id: myCyberCashID
 transaction: 78784567
 date: 1995121100500.nnn
 merchant-date: 19950121100505.nnn
 merchant-response-code: failure/success/etc.
 pr-hash: 7Tm/djB05pLIw3JAyy5E7A==
 pr-signed-hash:
  a/0meaMHRinNVd8nq/fKsYg5AfTZZUCX0S3gkjAhZTmcrkp6RZvppmDd/P7lboFLFDBh
  Ec0oIyxWeHfArb3OtkgXxJ7qe0Gmm/87jG5ClGnpBnw0dY7qcJ6XoGB6WGnD
 merchant-message; This is a message to display to the user from the
     merchant. Can be multiple lines...  Is not secure.
 opaque:  [might not be present, see explanation]
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################

Eastlake, et al Informational [Page 24] RFC 1898 CyberCash Version 0.8 February 1996

 Opaque Key:   Same customer session key from CH1 passed through CM1
     for ID and Transaction
 #####################################################################
 Opaque Section Contents (from CM.6):
 server-date: 19950121100706.nnn
 amount: usd 10.00
 order-id: 1231-3424-234242
 card*:  [from successful BC4]
 response-code: failure/success/etc.
 swseverity: fatal/warning
 swmessage; Tells CyberApp that it is obsolete.  Display this
  text to the user.  [only present if SWSeverity present]
 message;
        Free text of the error/success condition.
        This text is to be displayed to the customer
        by the CyberCash application...
 #####################################################################
 Signature is of the following fields: no signature
 #####################################################################
 Explanation:
 Opaque section optional because the CH1 to the merchant can fail due
     to bad order-id, date, wrong merchant-ccid, etc., etc. So the
     server may not be involved at all in which case there is no
     mechanism for generating a secure opaque section.  (It could even
     be that merchant attempt to contact the server times out.)
 If transaction makes it through server (via CM*) then
     Response-Code at top level should mirror response-code to
     merchant from server. (Hopefully the same as the
     response-code to customer from server but the merchant can't
     tell that.)
 Note that there can be two messages, one from merchant and one
     from the server.

4.4 Merchant Credit Card Purchasing Messages

 The merchant presents credit card purchases, makes adjustments, and
 the like via the CM* series.  In general, the credit card cycle is
 one of getting authorization for a purchase, then capturing the
 purchase in a batch for clearance, then performing the clearance.  It
 is also possible to void a capture (i.e., remove an item from a
 batch), and process credits (returns). (See section 5.1.)

Eastlake, et al Informational [Page 25] RFC 1898 CyberCash Version 0.8 February 1996

 Authorizations always come from an acquirer via the response to a CM1
 or CM2 message. If capture is being performed by the acquirer or some
 entity between the CyberCash server and the acquirer, this is done
 via a CM3 or CM2 message depending on the arrangement between the
 merchant and the entity doing the capture.  Returns (credits) are
 handled via message CM5.  Message CM4 is provided for voiding a
 capture or return before the batch is cleared.  CM6 is the message
 format used for responses to all the other CM* messages.
 An MM* series has also been implemented for purely merchant
 originated CyberCash charges as described in section 3.4.7
 Current credit card dispute resolution systems assume that the
 merchant knows the card number.  Thus, to work with these systems,
 special bypass messages have been set up that allow the merchant to
 obtain, for a particular transaction, the information that CyberCash
 otherwise goes to lengths to hide from the merchant.  See sections
 3.4.8 and 3.4.9.  This makes the obtaining os such information by the
 merchant an auditable event.
 Many present day merchants operate in a "terminal capture" mode where
 the authorizations are captured by the merchant and the merchant
 later submits the settlement batch.  Messages have been defined and
 are being implemented so that such merchant captured batches can be
 submitted via CyberCash.

4.4.1 CM1 - auth-only

 Description: This message is used by the merchant to perform an
     authorization operation on the credit card sent in by the
     customer.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: ACME-69
 merchant-transaction: 123123
 merchant-date: 19950121100705.nnn
 merchant-cyberkey: CC1001
 cyberkey: CC1001
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV

Eastlake, et al Informational [Page 26] RFC 1898 CyberCash Version 0.8 February 1996

  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 merchant-opaque:
  6BVEfSlgVCoGh1/0R+g1C143MaA6QLvKpEgde86WWGJWx45bMUZvaAu4LVeqWoYCqSGf
  aWKUF7awol0h1i1jtgieyAcXB8ikvRJIsupSAwsRMyoNlekR6tucvfv/622JY7+n7nGO
  dGbMzP0GJImh2DmdPaceAxyOB/xOftf6ko0nndnvB+/y2mFjdUGLtFQP/+3bTpZttZXj
  j7RO1khe1UrAIk2TGQJmNw+ltsu0f42MgsxB8Q31vjPtoiPi5LEmD0Y4jlpJ7Jg2Ub84
  F9vJhYpmzNkdiJUe83Hvo/xfJRbhafJpXFEsUZwQK0jU1ksU6CQd2+CPBB+6MxtsHoxJ
  mjD6ickhd+SQZhbRCNerlTiQGhuL4wUAxzGh8aHk2oXjoMpVzWw2EImPu5QaPEc36xgr
  mNz8vCovDiuy3tZ42IGArxBweasLPLCbm0Y=
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Merchant-Opaque Section Contents:
 type: auth-only
 order-id: 12313424234242
 merchant-amount: usd 10.00
 pr-hash: 7Tm/djB05pLIw3JAyy5E7A==
 pr-signed-hash:
  a/0meaMHRinNVd8nq/fKsYg5AfTZZUCX0S3gkjAhZTmcrkp6RZvppmDd/P7lboFLFDBh
  Ec0oIyxWeHfArb3OtkgXxJ7qe0Gmm/87jG5ClGnpBnw0dY7qcJ6XoGB6WGnD
 id: myCyberCashID
 transaction: 78784567
 date: 19950121100505.nnn
 merchant-signature:
  v4qZMe2d7mUXztVdC3ZPMmMgYHlBA7bhR96LSehKP15ylqR/1KwwbBAX8CEqns55UIYY
  GGMwPMGoF+GDPM7GlC6fReQ5wyvV1PnETSVO9/LAyRz0zzRYuyVueOjWDlr5
 #####################################################################
 merchant-opaque key is generated from the CyberCash encrypting public
      key identified in merchant-cyberkey.
 Customer opaque section (Opaque) - see CH1.
 #####################################################################
 Opaque Section Contents & Signature:  (exactly as in CH1)
 swversion: 0.8win
 amount: usd 10.00
 card*: [from successful BC4 (includes card-expiration-date,
     card-number, and card-salt)]
 signature:
  48SBKUfojyC9FDKCwdCYNvucgiDxYO9erZW4QndIXZRyheTHXH8OeIhwUkyLmgQSD/UK
  +IX9035/jUkdNPOxUQq9y/beHS1HU9Fe0wlzfXYRtnjlqvQX+yUfQ4T7eNEs
 #####################################################################

Eastlake, et al Informational [Page 27] RFC 1898 CyberCash Version 0.8 February 1996

 merchant-signature is on the following fields: merchant-ccid,
     merchant-transaction, merchant-date, merchant-cyberkey, type,
     order-id, merchant-amount, pr-hash, pr-signed-hash, id,
     transaction, date, cyberkey
 Customer Signature: see CH1
 #####################################################################
 Explanation:
 The merchant signature ensures integrity of the majority of the
     message.  validation of the customer signature ensures that the
     customer opaque part was not tampered or replaced.

4.4.2 CM2 - auth-capture

 Description: Do authorization and actually enters charge for
     clearance. Message just like CM1 except for different
     type.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 [exactly the same as CM1 except
 type: auth-capture
 ]

4.4.3 CM3 - post-auth-capture

 Description: Captures a charge previously authorized. Message is
     the same as CM1 except that it also has an authorization-code
     field (which is also included in the signature) and the type
     is different.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: ACME-012

Eastlake, et al Informational [Page 28] RFC 1898 CyberCash Version 0.8 February 1996

 merchant-transaction: 123123
 merchant-date: 19950121100705.nnn
 merchant-cyberkey: CC1001
 cyberkey: CC1001
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 merchant-opaque:
  6BVEfSlgVCoGh1/0R+g1C143MaA6QLvKpEgde86WWGJWx45bMUZvaAu4LVeqWoYCqSGf
  aWKUF7awol0h1i1jtgieyAcXB8ikvRJIsupSAwsRMyoNlekR6tucvfv/622JY7+n7nGO
  dGbMzP0GJImh2DmdPaceAxyOB/xOftf6ko0nndnvB+/y2mFjdUGLtFQP/+3bTpZttZXj
  j7RO1khe1UrAIk2TGQJmNw+ltsu0f42MgsxB8Q31vjPtoiPi5LEmD0Y4jlpJ7Jg2Ub84
  F9vJhYpmzNkdiJUe83Hvo/xfJRbhafJpXFEsUZwQK0jU1ksU6CQd2+CPBB+6MxtsHoxJ
  mjD6ickhd+SQZhbRCNerlTiQGhuL4wUAxzGh8aHk2oXjoMpVzWw2EImPu5QaPEc36xgr
  mNz8vCovDiuy3tZ42IGArxBweasLPLCbm0Y=
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Merchant-Opaque Section Contents:
 type: post-auth-capture
 authorization-code: a12323
 order-id: 1231-3424-234242
 merchant-amount: usd 10.00
 pr-hash: 7Tm/djB05pLIw3JAyy5E7A==
 pr-signed-hash:
  a/0meaMHRinNVd8nq/fKsYg5AfTZZUCX0S3gkjAhZTmcrkp6RZvppmDd/P7lboFLFDBh
  Ec0oIyxWeHfArb3OtkgXxJ7qe0Gmm/87jG5ClGnpBnw0dY7qcJ6XoGB6WGnD
 id: myCyberCashID
 transaction: 78784567
 date: 19950121100505.nnn
 merchant-signature:
  vxyEF1ZHn5Rgmtms3H3t/+UB6RAvZQA1AdddjvlS0H75N1x83FyJuh8V9Ok6t4EUQQZ6
  Mnptzc6phJi3Ar0s0oumELsdc8upJdXpNpJV021PGJXfDKfHP0heJIWLodXr
 #####################################################################
 merchant-opaque key is generated from the CyberCash encrypting public
      key identified in merchant-cyberkey.
 Customer opaque section (Opaque) - see CH1.
 #####################################################################
 Opaque Section Contents & Signature:  (exactly as in CH1)
 swversion: 0.8win

Eastlake, et al Informational [Page 29] RFC 1898 CyberCash Version 0.8 February 1996

 amount: usd 10.00
 card*: [from successful BC4 (includes card-salt, card-number,
     and card-expiration)]
 signature:
  48SBKUfojyC9FDKCwdCYNvucgiDxYO9erZW4QndIXZRyheTHXH8OeIhwUkyLmgQSD/UK
  +IX9035/jUkdNPOxUQq9y/beHS1HU9Fe0wlzfXYRtnjlqvQX+yUfQ4T7eNEs
 #####################################################################
 merchant-signature is on the following fields: merchant-ccid,
     merchant-transaction, merchant-date, merchant-cyberkey, type,
     authorization-code, order-id, merchant-amount, pr-hash,
     pr-signed-hash, id, transaction, date, cyberkey
 #####################################################################
 Explanation:
 The merchant signature ensures integrity of the majority of the
     message validation of the customer signature ensures that the
     customer opaque part was not tampered or replaced.

4.4.4 CM4 - void

 Description: Voids out a charge/return if received before
     clearance.  Message is the same as CM1 except that it also has
     a retrieval-reference-number field (which is also included in the
     signature) and the type is different.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: ACME-012
 merchant-transaction: 123123
 merchant-date: 19950121100705.nnn
 merchant-cyberkey: CC1001
 cyberkey: CC1001
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 merchant-opaque:
  6BVEfSlgVCoGh1/0R+g1C143MaA6QLvKpEgde86WWGJWx45bMUZvaAu4LVeqWoYCqSGf
  aWKUF7awol0h1i1jtgieyAcXB8ikvRJIsupSAwsRMyoNlekR6tucvfv/622JY7+n7nGO

Eastlake, et al Informational [Page 30] RFC 1898 CyberCash Version 0.8 February 1996

  dGbMzP0GJImh2DmdPaceAxyOB/xOftf6ko0nndnvB+/y2mFjdUGLtFQP/+3bTpZttZXj
  j7RO1khe1UrAIk2TGQJmNw+ltsu0f42MgsxB8Q31vjPtoiPi5LEmD0Y4jlpJ7Jg2Ub84
  F9vJhYpmzNkdiJUe83Hvo/xfJRbhafJpXFEsUZwQK0jU1ksU6CQd2+CPBB+6MxtsHoxJ
  mjD6ickhd+SQZhbRCNerlTiQGhuL4wUAxzGh8aHk2oXjoMpVzWw2EImPu5QaPEc36xgr
  mNz8vCovDiuy3tZ42IGArxBweasLPLCbm0Y=
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Merchant-Opaque Section Contents:
 type: void
 retrieval-reference-number: 432112344321
 order-id: 1231-3424-234242
 merchant-amount: usd 10.00
 pr-hash: WATCQuH2q17lRuoxD78YBg==
 pr-signed-hash:
  8zqw0ipqtLtte0tBz5/5VPNJPPonfTwkfZPbtuk5lqMykKDvThhO0ycrfT7eXrn/hLUC
  kXoSctahEVdw1KBJbp0EVr1zVzcN9Aa7m2fJgxNfiisTgIRW+PMaa78rn+Ov
 id: myCyberCashID
 transaction: 78784567
 date: 19950121100505.nnn
 Merchant-Signature: lkjladjslkjflsakjflkjsdljflsakjflkjsdljflsakjflkj
     flsakjflkjsdljflsakjflkjsdljflsajflksdjflksdjflsdjssf=
 #####################################################################
 Merchant-Opaque key is generated from the CyberCash encrypting public
      key identified in Merchant-CyberKey.
 Customer opaque section (Opaque) - see CH1.
 #####################################################################
 Opaque Section Contents & Signature:  (exactly as in CH1)
 swversion: 0.8win
 amount: usd 10.00
 card*: [from successful bc4 (includes card-salt, card-number,
     and card-expiration)]
 signature:
  48SBKUfojyC9FDKCwdCYNvucgiDxYO9erZW4QndIXZRyheTHXH8OeIhwUkyLmgQSD/UK
  +IX9035/jUkdNPOxUQq9y/beHS1HU9Fe0wlzfXYRtnjlqvQX+yUfQ4T7eNEs
 #####################################################################
 merchant-signature is on the following fields: merchant-ccid,
     merchant-transaction, merchant-date, merchant-cyberkey, type,
     retrieval-reference-number, order-id, merchant-amount, pr-hash,
     pr-signed-hash, id, transaction, date, cyberkey
 #####################################################################

Eastlake, et al Informational [Page 31] RFC 1898 CyberCash Version 0.8 February 1996

 Explanation:
 The merchant signature ensures integrity of the majority of the
     message.  Validation of the customer signature ensures that the
     customer opaque part was not tampered or replaced.

4.4.5 CM5 - return

 Description: Reverse a previous charge.  Really sort of a negative
     charge.  Message just like CM1 except for different type.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 [exactly the same as CM1 except
 type: return
 ]

4.4.6 CM6 - charge-action-response

 Description: This receipt is given to the merchant as a receipt
     for a completed charge action.  Indicates success/failure/etc.
 #####################################################################
 Sender: CyberServer
 Receiver: MerchantApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: ACME-012
 merchant-transaction: 123123
 merchant-date: 19950121100705.nnn
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 merchant-opaque:
  6BVEfSlgVCoGh1/0R+g1C143MaA6QLvKpEgde86WWGJWx45bMUZvaAu4LVeqWoYCqSGf
  aWKUF7awol0h1i1jtgieyAcXB8ikvRJIsupSAwsRMyoNlekR6tucvfv/622JY7+n7nGO

Eastlake, et al Informational [Page 32] RFC 1898 CyberCash Version 0.8 February 1996

  dGbMzP0GJImh2DmdPaceAxyOB/xOftf6ko0nndnvB+/y2mFjdUGLtFQP/+3bTpZttZXj
  j7RO1khe1UrAIk2TGQJmNw+ltsu0f42MgsxB8Q31vjPtoiPi5LEmD0Y4jlpJ7Jg2Ub84
  F9vJhYpmzNkdiJUe83Hvo/xfJRbhafJpXFEsUZwQK0jU1ksU6CQd2+CPBB+6MxtsHoxJ
  mjD6ickhd+SQZhbRCNerlTiQGhuL4wUAxzGh8aHk2oXjoMpVzWw2EImPu5QaPEc36xgr
  mNz8vCovDiuy3tZ42IGArxBweasLPLCbm0Y=
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Merchant-Opaque Key: Session key same as that of CM1/2/3/4/5 for
     same Merchant-Transaction and Merchant-CCID.
 Opaque Key:  Same customer session key from CH1 passed through CM*
     for ID and Transaction
 #####################################################################
 Merchant-Opaque Section Contents:
 type: charge-action-response
 server-date: 19950121100706.nnn
 action-code: XXX  [per ISO 8583]
 response-code: failure/success/etc.
 order-id: 1231-3424-234242
 pr-hash: 7Tm/djB05pLIw3JAyy5E7A==
 pr-signed-hash:
  8zqw0ipqtLtte0tBz5/5VPNJPPonfTwkfZPbtuk5lqMykKDvThhO0ycrfT7eXrn/hLUC
  kXoSctahEVdw1KBJbp0EVr1zVzcN9Aa7m2fJgxNfiisTgIRW+PMaa78rn+Ov
 retrieval-reference-number: 432112344321
 authorization-code: a12323
 card-hash: 7Tm/djB05pLIw3JAyy5E7A==
 {
 card-prefix: nnxxxx  [Returned if merchant is not full-PAN]
 }
     or
 {
 card-number: 1234567890123456  [Returned if merchant is full-PAN]
 }
 expiration-date: 12/34  [always present]
 merchant-swseverity: fatal/warning
 merchant-swmessage; Message for merchant about out of date
     protocol number in $$ start line of merchant message.
 merchant-message;
        Free text of the error/success condition.
        This text is for the merchant from the server...
 id: myCyberCashID
 transaction: 78784567
 date: 19950121100505.nnn
 Opaque (Customer) contents:

Eastlake, et al Informational [Page 33] RFC 1898 CyberCash Version 0.8 February 1996

 server-date: 19950121100706.nnn
 amount: usd 10.00
 order-id: 1231-3424-234242
 card*: [from successful BC4]
 response-code: failure/success/etc.
 swseverity: fatal/warning
 swmessage; Tells CyberApp that it is obsolete display this
  text to the user.  [only present if SWSeverity present]
 message;
        Free text of the error/success condition.
        This text is to be displayed to the customer
        by the CyberCash application...
 #####################################################################
 Signature is of the following fields: no signature
 #####################################################################
 Explanation:
 retrieval-reference-number is needed for voids. authorization-code
     is needed for post-auth-capture.  These fields are each only
     present in the CM6 if they were returned by the bank which
     depends on what operation was being done.
 card-prefix is first two and last four digits of card-number.
 At merchant's bank's discretion the card-number or card-prefix is
     returned.
 card-hash is really the hash of the full card number and the salt
     provided by the customer.  card-hash is needed so the merchant
     can, if they wish, sort customer transactions by card without
     knowing the card number.
 card* is the card* fields delivered in the CM* messages being
     responded to.  They appear in alphabetic order.
 server-date duplicated in customer opaque area for security.
 {}'s in column one just for clarity of alternatives and do not
     actually appear in the message.
 []ed comments appear after some fields.

4.4.7 The MM* Message Series

 The CM* message series above is the primary CyberCash credit card
 purchase system for securely handling charges from CyberCash
 customers.  However, merchants, who are authorized by their acquiring
 bank to accept such charges, may also receive telephone, mail, and
 over-the-counter sales.  To avoid any necessity for the merchant to
 have a second parallel system to handle these charges, an MM1 through
 MM6 message series is defined and has been implemented for these less
 secure transactions.

Eastlake, et al Informational [Page 34] RFC 1898 CyberCash Version 0.8 February 1996

 The MM* messages look very similar to the CM* series but the
 "customer opaque" section is actually signed by the merchant and no
 separate customer CyberCash ID or prior card binding is required.
 The MM* message examples are omitted here in the interests of
 brevity.

4.4.8 CD1 - card-data-request

 Description: Used by merchant to get card-number, etc., if
     information needed by merchant to resolve a dispute.
 #####################################################################
 Sender: MerchantApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: ACME-69
 merchant-transaction: 123123
 merchant-date: 19950121100705.nnn
 merchant-cyberkey: CC1001
 cyberkey: CC1001
 opaque:
  EDD+b9wAfje5f7vscnNTJPkn1Wdi7uG3mHi8MrzLyFC0dj7e0JRjZ2PmjDHuR81kbhqb
  nX/w4uvsoPgwM5UJEW0Rb9pbB39mUFBDLPVgsNwALySeQGso0KyOjMxNs1mSukHdOmDV
  4uZR4HLRRfEhMdX4WmG/2+sbewTYaCMx4tn/+MNDZlJ89Letbz5kupr0ZekQlPix+pJs
  rHzP5YqaMnk5iRBHvwKb5MaxKXGOOef5ms8M5W8lI2d0XPecH4xNBn8BMAJ6iSkZmszo
  QfDeWgga48g2tqlA6ifZGp7daDR81lumtGMCvg==
 merchant-opaque:
  6BVEfSlgVCoGh1/0R+g1C143MaA6QLvKpEgde86WWGJWx45bMUZvaAu4LVeqWoYCqSGf
  aWKUF7awol0h1i1jtgieyAcXB8ikvRJIsupSAwsRMyoNlekR6tucvfv/622JY7+n7nGO
  dGbMzP0GJImh2DmdPaceAxyOB/xOftf6ko0nndnvB+/y2mFjdUGLtFQP/+3bTpZttZXj
  j7RO1khe1UrAIk2TGQJmNw+ltsu0f42MgsxB8Q31vjPtoiPi5LEmD0Y4jlpJ7Jg2Ub84
  F9vJhYpmzNkdiJUe83Hvo/xfJRbhafJpXFEsUZwQK0jU1ksU6CQd2+CPBB+6MxtsHoxJ
  mjD6ickhd+SQZhbRCNerlTiQGhuL4wUAxzGh8aHk2oXjoMpVzWw2EImPu5QaPEc36xgr
  mNz8vCovDiuy3tZ42IGArxBweasLPLCbm0Y=
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Merchant-Opaque Section Contents:
 type: card-data-request
 password: xyzzy
 server-date: 19950121100505.nnn  [optional]
 order-id: 12313424234242
 merchant-amount: usd 10.00
 pr-hash: 7Tm/djB05pLIw3JAyy5E7A==

Eastlake, et al Informational [Page 35] RFC 1898 CyberCash Version 0.8 February 1996

 pr-signed-hash:
  IV8gWHx1f8eCkWsCsMOE3M8mnTbQ7IBBcEmyGDAwjdbaLu5Qm/bh06OX1npe2d3Hijxy
  +X8vKcVE6l6To27u7A7UmGm+po9lCUSLxgtyqyn3jWhHZpc5NZpwoTCf2pAK
 id: myCyberCashID
 transaction: 78784567
 date: 19950121100505.nnn
 merchant-signature:
  8zqw0ipqtLtte0tBz5/5VPNJPPonfTwkfZPbtuk5lqMykKDvThhO0ycrfT7eXrn/hLUC
  kXoSctahEVdw1KBJbp0EVr1zVzcN9Aa7m2fJgxNfiisTgIRW+PMaa78rn+Ov
 #####################################################################
 merchant-opaque key is generated from the CyberCash encrypting public
      key identified in merchant-cyberkey.
 Customer opaque section (Opaque) - see CH1.
 #####################################################################
 Opaque Section Contents & Signature:  (exactly as in CH1)
 swversion: 0.8win
 amount: usd 10.00
 card*: [from successful BC4 (includes card-expiration-date,
     card-number, and card-salt)]
 signature:
  48SBKUfojyC9FDKCwdCYNvucgiDxYO9erZW4QndIXZRyheTHXH8OeIhwUkyLmgQSD/UK
  +IX9035/jUkdNPOxUQq9y/beHS1HU9Fe0wlzfXYRtnjlqvQX+yUfQ4T7eNEs
 #####################################################################
 merchant-signature is on the following fields: merchant-ccid,
     merchant-transaction, merchant-date, merchant-cyberkey, type,
     password, server-date, order-id, merchant-amount, pr-hash,
     pr-signed-hash, id, transaction, date, cyberkey
 Customer Signature: see CH1
 #####################################################################
 Explanation:
 [see also CM1 explanation]
 The merchant may need to know the card involved and other
     information in order to resolve a disputed transaction.  This
     information is all contained in the original CH1 embedded in the
     CM1 for the transaction.  If the merchant saves the CM1 and other
     transaction information, they can send this CD1 message to the
     server.  While this reduces the pass through confidentiality of
     the system, the merchant is then on record as asking for this
     particular credit card number and excessive CD1's from a merchant
     can be flagged.
 password is an extra level of security intended to be manually entered

Eastlake, et al Informational [Page 36] RFC 1898 CyberCash Version 0.8 February 1996

     at the merchant to authorize the unusual action.  Server stores a
     hash of the merchant-ccid and the password.

4.4.9 CD2 - card-data-response

 Description: Respond to CD1 with failure or with success and card
     data.
 #####################################################################
 Sender: CyberServer
 Receiver: MerchantApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: ACME-012
 merchant-transaction: 123123
 merchant-date: 19950121100705.nnn
 merchant-opaque:
  t731/86R72ZLrqHLIf0VG6m3ybvs+dG6K705L8LFKEXgCti0NGjK83CwDsUdiso7U1JP
  2Z0BClVHLmhIBY7+QXx5iCEGHy8JKC9IWyNNi2O/OOIDgLeJAkMSZYbNQrSKViY34imS
  0s7Q6uDk9wV0fixjvRBuNO2B7urWWsqfkLOYDnHy0RvhyUzYxLrMaTX+/6IkyU5Z0lH3
  BXYBUNV8DgitEjgLXmyWuXRDlEBN02yeZgsFRm9GmuBHfCTySm2XqnifizpmKMUa9UiH
  onNx9W86fuBdcJF7CJgH5Gct2M/dx/f2VpoRkmeSmWxFrYi8wgtvddSXF9my40NZ8WZz
  CEUEvQhcmruopwEeehv+bejc3fDDZ23JKrbhlZ17lSvFR14PKFsi32pXFqTO0ej9GTc5
  L6c8nM3tI1qdHNCe0N5f7ASdKS0tYSxAYJLIR6MqPrXjNJEaRx7Vu1odMlkgrzGOV1fo
  5w33BQHK3U2h+1e5zYBeHY3ZYG4nmylYYXIye4xpuPN4QU0dGrWZoImYE44QOwjd5ozl
  xulPBjj6cpEI/9wTwR3tpkBb4ZfYirxxnoj9JUkPK9Srv9iJ
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Opaque Key: session key from CD1.
 #####################################################################
 Opaque Section Contents:
 type: card-data-response
 server-date: 19950121100706.nnn
 response-code: failure/success/etc.
 order-id: 1231-3424-234242
 pr-hash: 7Tm/djB05pLIw3JAyy5E7A==
 pr-signed-hash:
  IV8gWHx1f8eCkWsCsMOE3M8mnTbQ7IBBcEmyGDAwjdbaLu5Qm/bh06OX1npe2d3Hijxy
  +X8vKcVE6l6To27u7A7UmGm+po9lCUSLxgtyqyn3jWhHZpc5NZpwoTCf2pAK
 card-hash: 7Tm/djB05pLIw3JAyy5E7A==
 card-number: 4811123456781234
 card-type: visa

Eastlake, et al Informational [Page 37] RFC 1898 CyberCash Version 0.8 February 1996

 card-name: John Q. Public
 expiration-date: 01/99
 merchant-swseverity: fatal/warning
 merchant-swmessage; Message for merchant about out of date
     protocol number in $$ start line of merchant message.
 merchant-message;
        Free text of the error/success condition.
        This text is for the merchant from the server...
 id: myCyberCashID
 transaction: 78784567
 date: 19950121100505.nnn
 #####################################################################
 Signature is of the following fields: no signature.
 #####################################################################
 Explanation:
 This normally returns selected fields from the decoding of the
     opaque part of a CH1 as sent to the server in a CD1.

4.5 Utility and Error Messges

 A number of utility, status query, and special error reporting
 messages have also been found necessary in implementing the CyberCash
 system.
 It is desirable to be able to test connectivity, roughly synchronize
 clocks, and get an initial determination of what client protocol and
 software versions are accepted.  This is done via the P1 client to
 server message and its P2 server to client response.
 Clients need to be able to determine the status of earlier
 transactions when the client or merchant has crashed during or has
 suffered data loss since the transaction.  Two transaction query
 messages are defined, TQ1 and TQ2.  One just queries and the other
 also cancels the transaction, if it has not yet completed.  The
 response to both of these messages is a TQ3 response from the server.
 Since the system operates in a query response mode, there are two
 cases where special error messages are needed.  If a query seems to
 be of an undeterminable or unknown type, the UNK1 response error
 message is sent.  If a response seems to be of an undeterminable or
 unknown type or other serious error conditions occur at the client or
 merchant which should be logged at the CyberCash server, the DL1 or
 DL2 diagnostic log message is submitted by the client or merchant in
 question respectively.

Eastlake, et al Informational [Page 38] RFC 1898 CyberCash Version 0.8 February 1996

4.5.1 P1 - ping

 Description: Very light weight check that we have connectivity from
     the customer to the server.  Does no crypto to minimize
     overhead.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 type: ping
 id: myCyberCashID  [optional]
 transaction: 123123213
 date: 19950121100505.nnn
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Explanation:
 id optional as persona may not have been set up yet.

4.5.2 P2 - ping-response

 Description: Response to the P1 light weight ping.  Does no
     crypto to minimize overhead.
 #####################################################################
 Sender: CyberServer
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 type: ping-response
 id: myCyberCashID  [if present in P1]
 transaction: 12312313
 date: 19950121100505.nnn
 server-date: 19950121100506.nnn
 swseverity: fatal/warning  [absent if ok]
 swmessage; Tells CyberApp that it is using an obsolete protocol.
      Display this text to the user.  [only present if SWSeverity
     present]
 response-code: success/failure/etc.
 message;
        Free text of the error/success condition.
        This text is to be displayed to the sender

Eastlake, et al Informational [Page 39] RFC 1898 CyberCash Version 0.8 February 1996

        by their CyberCash application...
 supported-versions: 08.win, 0.81win, 0.8mac
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Explanation:
 swversion does not appear in P1 for security reasons so
     swseverity and swmessage appear only if the server can tell
     that things are old from the $$ header protocol version.
 supported-versions lets client know as soon as possible what
     versions are supported and, by implication, which are not. Does
     not compromise security by having client say what version it
     is.

4.5.3 TQ1 - transaction-query

 Description: Client query to server for Transaction status.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 id: MyCyberCashID
 date: 19950121100505.nnn
 transaction: 12312314
 cyberkey: CC1001
 opaque:
  VFaztHuj757Jrv+JxZFsHORy/zgkrxhBCu9cPdE04c1NnXzVlGOHygpSl+UGbUvnhkYl
  21QQaHkaE3geccRk03cqFYoLNRCclImcsyeIZCgVt+2dJTj1V+E7R7ePQtCj+0gY42+V
  L5BWhVtmDQFyg1DdJ6n3S/er6ZuObAjpcAogG+T1Na5dJmrTA1wRMiYVkqhXi2KMYdur
  3U47P8ZGUza7W0MST3DgvviN0kVhtmHEnm515mo6NTQdfdxw9WZpy6vMqrBGk2nTgi2c
  bnf+muO0+kiNPXVvEzRrO8o=
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: generated from CyberCash encryption key identified in
     CyberKey
 #####################################################################
 Opaque Section Contents:
 type: transaction-query
 swversion: 0.8win
 begin-transaction: 1234

Eastlake, et al Informational [Page 40] RFC 1898 CyberCash Version 0.8 February 1996

 end-transaction: 4321
 signature:
  jJfFsKvOxLaV87gxu7lIPet3wIDwh1H2F61reYC9jmUrS6WAtUVFG9aCNuTEBoMixF0X
  vD5oPfyheJRIlnL6i0c4o/bfyO3edKAacmWjTmKt6/4y9p3qgvKkSX8r9aym
 #####################################################################
 signature is of the following fields: id, date, transaction,
     cyberkey, type, swversion, begin-transaction,
     end-transaction
 #####################################################################
 Explanation:
 This is a client status query of a previous transaction or
     transactions.
 begin-transaction and end-transaction can be the same.

4.5.4 TQ2 - transaction-cancel

 Description: Client query to server for Transaction
     cancellation/status.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 id: MyCyberCashID
 date: 19950121100505.nnn
 transaction: 12312314
 cyberkey: CC1001
 opaque:
  VFaztHuj757Jrv+JxZFsHORy/zgkrxhBCu9cPdE04c1NnXzVlGOHygpSl+UGbUvnhkYl
  21QQaHkaE3geccRk03cqFYoLNRCclImcsyeIZCgVt+2dJTj1V+E7R7ePQtCj+0gY42+V
  L5BWhVtmDQFyg1DdJ6n3S/er6ZuObAjpcAogG+T1Na5dJmrTA1wRMiYVkqhXi2KMYdur
  3U47P8ZGUza7W0MST3DgvviN0kVhtmHEnm515mo6NTQdfdxw9WZpy6vMqrBGk2nTgi2c
  bnf+muO0+kiNPXVvEzRrO8o=
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: generated from CyberCash encryption key identified in
     CyberKey
 #####################################################################
 Opaque Section Contents:

Eastlake, et al Informational [Page 41] RFC 1898 CyberCash Version 0.8 February 1996

 type: transaction-cancel
 swversion: 0.8win
 begin-transaction: 1234
 end-transaction: 4321
 signature:
  kD7DEav2uLQIYMtP9gbhYaBUpB2a5whNwnK2eXbbyTCf56F6dl3DIVf7D8Z4WxbY2YZn
  ByRIKeqlhmss7fbdnBiDYmKfOuc+I4bi/Oslml5riaciQhTd2JdHG+PCcHwZ
 #####################################################################
 signature is of the following fields: id, date, transaction,
     cyberkey, type, swversion, begin-transaction, end-transaction
 #####################################################################
 Explanation:
 This is a client attempt to cancel a previous transaction or
     transactions.
 begin-transaction and end-transaction can be the same.
 The transaction-cancel transaction (TQ.2) is defined between the
 client and the server.  This transaction permits the client to
 query the status of an operation and to stop the operation from
 occurring if it has not already occurred.

4.5.5 TQ3 - transaction-response

 Description: Reports generated by a TQ1 or TQ2
 #####################################################################
 Sender: CyberServer
 Receiver: CyberApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 id: mycybercashid
 date: 19950121100505.nnn
 transaction: 12312314
 server-date: 19950121100505.nnn
 opaque:
  eFXRL+H0J5q318M21wRdtcbhu9WCyLysQkeF9oIcjtbstymx343bbt0EAtU1gcJaUKJZ
  3skgvwrhcxU4bFcE68OPlUXAvLq10I3MczPYPsiGrsU0K4bZtQvDZmn727QQAfONBm5s
  s1yjIha+Fj481BJQs0CTYc3ju90lAjCYgirXtnnR6yJXoDO75b7UjthvHSnrTWVZvktX
  PvTuUCYzbXSFoYvwFM3Y+yHqSHlmWutYKQpYze8zbUSDQfmwTCJyw3aY2JasZ+xMP/CD
  JWbCA+gCLBYCnvzM/ExKTZTFD3xr5JBfNbV4p6CiK6lsfRFD7maAK6TSVnWjwCEJNpOv
  fyllfWD04fT7LINQcjJiQK1Pk/912Tk6Q35eRaQZorwv2hnY/7By2OkPyFdAqFL+D0H6
  TqzxmdEjEFKxi/PPT1+Cs/Nszy8wZzaGg8iWATfARY6stl+02dDhwOoFXSBNvchlVrcI
  IlvhumSIQs29Pntj3DbkYo4IEmmN/qi1vnzld22q7lA1q/CQakyc7jlQUFISx76buqwy

Eastlake, et al Informational [Page 42] RFC 1898 CyberCash Version 0.8 February 1996

  35XiC9Yn8flE4Va14UxMf2RCR1B/XoV6AEd64KwPeCYyOYvwbRcYpRMBXFLyYgWM+ME1
  +yp7c66SrCBhW4Q8AJYQ+5j5uyO7uKyyq7OhrV0IMpRDPjiQXZMooLZOifJPmpvJ66hC
  VZuWMuA6LR+TJzWUm4sUP9Zb6zMQShedUyOPrtw1vkJXU1vZ5aI8OJAgUcLEitcD+dsY
  Df4CzA00fC10POkJ58HZB/pSBfUrHAa+IqMHyZkV/HBi9TjTwmktJi+8T9orXS0jSvor
  dMTGWn0ifETy2VXt
 $$-CyberCash-End-0QXqLlNxrn4GNQPPk9AO1Q==-$$
 #####################################################################
 Opaque Key: Session key from TQ1/TQ2 with same Transaction and ID.
 #####################################################################
 Opaque Section Contents:
 type: transaction-response
 response-code: success/failure/etc.
 message; general free form text message from server to
     customer....
 swseverity: fatal/warning
 swmessage; Message indicating that CyberApp software is obsolete.
     May be multiple lines.
 report-fee: usd 0.15  [if non-zero]
 transaction-1: old-transaction-number
 transaction-status-1: success/failure/pending/cancelled/etc.
 server-date-1: 19951212125959.nnn
 date-1: 19950121100505.nnn
 type-1: auth-only/etc.
 #####################################################################
 Signature is of the following fields:  no signature
 #####################################################################
 Explanation:
 Report-fee is the notification that this report cost a fee and is
     only present if there is a fee.
 There can be multiple transaction for the same transaction number as
     there could have been a auth, post-auth-capture, void, etc.
 Terms
     "original transaction" refers to the payment or other transaction
 that is being queried or canceled.
        Note: this transaction may not actually reside at the server.
     "request" refers to the requesting TQ.2 or TQ.1 message
 id: id from the request message
 date: date from the request message
 transaction: transaction from the request message

Eastlake, et al Informational [Page 43] RFC 1898 CyberCash Version 0.8 February 1996

 server-date: current date/time
 type: transaction-response
 response-code: response code for request message, can be one of:
     "success" means the request message was processed.  Does not imply
     query or cancellation status of the request.
     "failure-hard" means that the request message was not processed
     due to being ill-formed or otherwise inoperable.
     "failure-swversion" means that the request message was not
     processed due to software revision problems.
 message: the message applies only to the TQ transaction, not to the
     status of the transactions being queried or canceled.  The
     message is provided according to the response-code as: "success"
     - message is omitted. "failure-hard" - use standard hard failure
     message. "failure-swversion" - use standard swversion message for
     fatal
 swseverity: applies to request message
 swmessage: applies to request message
  -- per query/cancel fields ('N' is a series from 1 to N) --
 transaction-N: transaction number of original transaction, or if
     the original transaction is not present in server the transaction
     number that the query / cancel request refers to
 transaction-status-N: status of original transaction, may be one of:
     "success" the original transaction was successfully processed.
     If request was TQ.2, cancellation is not performed.
     "failure" the original transaction was not successfully processed.
      If request was TQ.2, cancellation is not performed (however,
     there is nothing to cancel, so it's all the same to the customer
     app).
     "pending" the original transaction is still being processed and
     final disposition is not known.
 "canceled" the original transaction has been canceled by the server.
     Later arrival of the original transaction will not be processed,
     but will be returned with a "failure-canceled" returned.
 server-date-1: server-date field from original transaction or
     omitted if original transaction is not present in the server"
 date-1: date field from original transaction or omitted if original
     transaction is not present in the server"
 type-1: type field from original transaction or omitted if original
     transaction is not present in the server"

4.5.6 UNK1 - unknown-error

 Description: This is the response sent when the request is so
     bad off you can't determine what type it is or the type is
     unknown to you.  Sent from Merchant to Client or from Server
     to Merchant or from Server to Client.

Eastlake, et al Informational [Page 44] RFC 1898 CyberCash Version 0.8 February 1996

 #####################################################################
 Sender: MerchantApp or CyberServer
 Receiver: CyberApp or MerchantApp
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 type: unknown-error
 unknown-error-message:
     Text message of error condition to display to user.  (CyberCash
     wrapper not found, wrapper integrity check fails, unknown protocol
     version specified, unknown type specified, etc.)
 {
 server-date: 19950121100506.nnn  [if sent by server]
 }
     or
 {
 merchant-date: 19950121100506.nnn  [if sent by merchant]
 }
 x-id: mycybercashID
 x-transaction: 123123213
 x-date: 19950121100505.nnn
 x-cyberkey: CC1001
 x-opaque:
  2DqiOQfGRZjzddWpEZwGsJnoTsp9Yiri8DE9cPUMPsJ7lTFuE4XHi4QfN2cAipDB2G/G
  9hr7Hj4u4xfMky7nPvJurClZejkI8eNp8iXLtrfS4DhR4yCFQjCiKk0dh83p+DDsFVV7
  TI3Du2B15sQS+SdaoPwkfVDnJv4Y+b7vu2cN7bG7exCkBapBcJZbReNaWX5sf+U8ypfw
  5V6QdMOzNXpef3z+cTTWfGOtmn9T1Pwo1Yi9ObyIf/wiK+IPb+bBZ9UwLZSB+qVMfJmX
  GnHXO3AnA/PD+jKYCtsm2Gxv2WB3CuezOyzPtORuqLp5ubgnLBF9aBBjxwLdbn+cp5sm
  lw51IHbmo1Jj7H6wyNnRpEjy4tM73jcosBfGeQDHxgyH1uaiFNr2D+WvmuYo7eun2dsy
  Wve2O/FwicWHvkg5aDPsgOjzetsn1JCNZzbW
 $$-CyberCash-End-7Tm/djB05pLIw3JAyy5E7A==-$$
 #####################################################################
 Opaque Key: see explanation
 #####################################################################
 Opaque Section Contents: see explanation
 #####################################################################
 Signature is of the following fields: see explanation
 #####################################################################
 Explanation:
 This message is sent as a response when you can't find or understand
     even the type of a message to you.  It will always have type and
     unknown-error-message fields at the beginning.  Any fields from
     the request that are parseable are simply echoed back in the UNK1

Eastlake, et al Informational [Page 45] RFC 1898 CyberCash Version 0.8 February 1996

     message with "x-" prefixed to it.  Thus, if an x-opaque appears,
     it was whatever the opaque was in the original request, etc.  If
     you can decrypt the opaque section, you don't want to put the
     results here in the clear!
 {}'s in the first column are to group alternatives only and do not
     appear in the message.
 Since the customer originates exchanges with merchant and server
     and merchant originates exchanges with server, this message
     will only be emitted from the merchant to the customer or the
     server to the customer or merchant. It should generally just
     be logged for debugging purposes.
 You may need to watch out for denial of service via forged or
     replayed UNK1 messages.

4.5.7 DL1 - diagnostic-log

 Description: Client diagnostic log of bad message from either
     merchant or server.
 #####################################################################
 Sender: CyberApp
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 id: MyCyberCashID
 date: 19950121100505.nnn
 transaction: 1234
 cyberkey: CC1001
 opaque:
  2DqiOQfGRZjzddWpEZwGsJnoTsp9Yiri8DE9cPUMPsJ7lTFuE4XHi4QfN2cAipDB2G/G
  9hr7Hj4u4xfMky7nPvJurClZejkI8eNp8iXLtrfS4DhR4yCFQjCiKk0dh83p+DDsFVV7
  TI3Du2B15sQS+SdaoPwkfVDnJv4Y+b7vu2cN7bG7exCkBapBcJZbReNaWX5sf+U8ypfw
  5V6QdMOzNXpef3z+cTTWfGOtmn9T1Pwo1Yi9ObyIf/wiK+IPb+bBZ9UwLZSB+qVMfJmX
  GnHXO3AnA/PD+jKYCtsm2Gxv2WB3CuezOyzPtORuqLp5ubgnLBF9aBBjxwLdbn+cp5sm
  lw51IHbmo1Jj7H6wyNnRpEjy4tM73jcosBfGeQDHxgyH1uaiFNr2D+WvmuYo7eun2dsy
  Wve2O/FwicWHvkg5aDPsgOjzetsn1JCNZzbW
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################
 Opaque Key: generated from CyberCash encryption key identified in
     CyberKey
 #####################################################################
 Opaque Section Contents:

Eastlake, et al Informational [Page 46] RFC 1898 CyberCash Version 0.8 February 1996

 type: diagnostic-log
 message: incorrect order-id
 swversion: 0.8win
 x-type: original-message-type
 x-transaction: original-transaction-number
 x-opaque: [if can't decrypt]
  9/eFiJK5tLizsoeSmpW7uLS8/7iio7Wisfv38biio7uyufv3tfv35uH+7N3d9/exuKX3
  5+z3vuu4oqO7srnsvvz8/venoqO0v7al/7iio7WisYy+iv7s3ff3p6KjtL+2pf/wi7nw
 #####################################################################
 Explanation:
 Client application does not expect a response for this message. The
     decrypted original message will be in the opaque section unless
     decryption fails. If decryption fails then un-decrypted opaque
     in the original will be sent.
 This message will be sent to a different script or socket or host
     than normal messages so that it will just be absorbed and never
     generate an UNK1 response or anything, even if this message
     itself is screwed up.

4.5.8 DL2 - merchant-diagnostic-log

 Description: Merchant diagnostic log of bad message from  server.
 #####################################################################
 Sender: CyberMerchant
 Receiver: CyberServer
 #####################################################################
 Sample Message:
 $$-CyberCash-0.8-$$
 merchant-ccid: MyCyberCashID
 merchant-transaction: 1234
 merchant-date: 19950121100505.nnn
 merchant-cyberkey: CC1001
 merchant-opaque:
  2DqiOQfGRZjzddWpEZwGsJnoTsp9Yiri8DE9cPUMPsJ7lTFuE4XHi4QfN2cAipDB2G/G
  9hr7Hj4u4xfMky7nPvJurClZejkI8eNp8iXLtrfS4DhR4yCFQjCiKk0dh83p+DDsFVV7
  TI3Du2B15sQS+SdaoPwkfVDnJv4Y+b7vu2cN7bG7exCkBapBcJZbReNaWX5sf+U8ypfw
  5V6QdMOzNXpef3z+cTTWfGOtmn9T1Pwo1Yi9ObyIf/wiK+IPb+bBZ9UwLZSB+qVMfJmX
  GnHXO3AnA/PD+jKYCtsm2Gxv2WB3CuezOyzPtORuqLp5ubgnLBF9aBBjxwLdbn+cp5sm
  lw51IHbmo1Jj7H6wyNnRpEjy4tM73jcosBfGeQDHxgyH1uaiFNr2D+WvmuYo7eun2dsy
  Wve2O/FwicWHvkg5aDPsgOjzetsn1JCNZzbW
 $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$
 #####################################################################

Eastlake, et al Informational [Page 47] RFC 1898 CyberCash Version 0.8 February 1996

 Opaque Key: generated from CyberCash encryption key identified in
     CyberKey
 #####################################################################
 Opaque Section Contents:
 type: merchant-diagnostic-log
 server-date:  19950121100505.nnn  [optional]
 message: incorrect order-id
 x-type: original-message-type
 x-transaction: original-transaction-number
 x-opaque: [if can't decrypt]
  9/eFiJK5tLizsoeSmpW7uLS8/7iio7Wisfv38biio7uyufv3tfv35uH+7N3d9/exuKX3
  5+z3vuu4oqO7srnsvvz8/venoqO0v7al/7iio7WisYy+iv7s3ff3p6KjtL+2pf/wi7nw
 #####################################################################
 Explanation:
 Merchant application does not expect a response for this message. The
     decrypted original message will be in the opaque section unless
     decryption fails. If decryption fails then un-decrypted message
     will be sent.
 This message will be sent to a different script or socket or host
     than normal messages so that it will just be absorbed and never
     generate an UNK1 response or anything even if this message
     itself is screwed up.

4.6 Table of Messages Described

 The following 31 messages are described in this document.
 C = Customer App, M = Merchant App, S = CyberCash Server
 FLOW  SECTION  NAME
 C->S   4.2.1   BC.1 bind-credit-card
 S->C   4.2.2   BC.4 bind-credit-card-response
 C->M   4.3.2   CH.1 credit-card-payment
 M->C   4.3.3   CH.2 credit-card-response
 M->S   4.4.8   CD.1 card-data-request
 S->M   4.4.9   CD.2 card-data-response
 M->S   4.4.1   CM.1 auth-only
 M->S   4.4.2   CM.2 auth-capture
 M->S   4.4.3   CM.3 post-auth-capture

Eastlake, et al Informational [Page 48] RFC 1898 CyberCash Version 0.8 February 1996

 M->S   4.4.4   CM.4 void
 M->S   4.4.5   CM.5 return
 S->M   4.4.6   CM.6 charge-action-response
 C->S   4.5.7   DL.1 diagnostic-log
 M->S   4.5.7   DL.2 merchant-diagnostic-log
 C->S   4.1.3   GA.1 get-application
 S->C   4.1.4   GA.2 get-application-response
 M->S   4.4.7   MM.1 merchant-auth-only
 M->S   4.4.7   MM.2 merchant-auth-capture
 M->S   4.4.7   MM.3 merchant-post-auth-capture
 M->S   4.4.7   MM.4 merchant-void
 M->S   4.4.7   MM.5 merchant-return
 S->M   4.4.7   MM.6 merchant-charge-action-response
 C->S   4.5.1   P.1 ping
 S->C   4.5.2   P.2 ping-response
 M->C   4.3.1   PR.1 payment-request
 C->S   4.1.1   R.1 registration
 S->C   4.1.2   R.2 registration-response
 C->S   4.5.3   TQ.1 transaction-query
 C->S   4.5.4   TQ.2 transaction-cancel
 S->C   4.5.5   TQ.3 transaction-response
 S->C, S->M, M->C
        4.5.6   UNK.1 unknown-error

5. Future Development

 CyberCash is extending the facilities available through the CyberCash
 system.  We are committed to implementing a full cash system,
 including efficient transfer of small amounts of money, the extension
 of the credit card system to handle terminal capture and clearances,
 and other improvements.

5.1 The Credit Card Authorization/Clearance Process

 There are six steps in credit card processing as listed below.  The
 first four are always involved if a transacation is completed.  The
 fifth and sixth are optional.
 (1) authorization: merchant contacts their acquiring back which
     normally contacts the card issung bank and returns to the
     merchant an approval/guarantee or a disapproval.  This

Eastlake, et al Informational [Page 49] RFC 1898 CyberCash Version 0.8 February 1996

     temporarily decreases the available credit on the card.
 (2) capture: the charge information for a purchase is entered by
     the merchant into a batch.
 (3) clearance: a batch of items is processed.  This actually causes
     the items in the batch to appear on credit card statements as
     sent by the issuing bank to its carholders.
 (4) settlement: the actual interbank transfer of net funds.
 (5) void: the merchant undoes step 2 (or 6) and causes a charge (or
     credit) to be removed from a batch.  Must be done before the
     batch is processed.
 (6) credit: the merchant causes a "negative charge" or credit to be
     entered into a batch.  This will appear on the cardholders
     statement.
 The fourth step, settlement, is entirely within the banking community
 and does not concern us here.  CyberCash 0.8 provides messages to do
 1, 1&2, 2, 5, and 6.  This is adequate for credit card processor
 systems where the batch is accumulated at the bank or between the
 bank and the merchant.  CyberCash 0.8 supports such "host capture"
 systems.  Other credit card processor systems require the merchant to
 accumulate the batch.  Such systems are frequently referred to as
 "terminal capture".  This makes actions 2, 5, and 6 internal to the
 merchant but requires messages to perform action 3.  Such batch
 clearance messages will be included in future versions of the
 CyberCash merchant and server software.

5.2 Lessons Learned

 The continuing rapid development of the CyberCash system is an
 interesting experience.  The system must deal with many existing
 browsers and legacy banking systems.  Existing credit card processors
 that convey transactions to acquiring banks have complex and varied
 interfaces.  The sophistication of security attacks on the Internet
 is growing rapidly.
 In the face of such a rapidly changing environment, it was essential
 to adopt a general message framework so that messages and fields
 could be added as they were found necessary.  Any attempt to reduce
 the system to a small number of perfectly opimized messages in
 advance would have doomed the system to failure.  (As of mid-October
 1995, the total number of CyberCash messages defined, including those
 planned for cash and microcash, enhancements to the credit card
 system, and some old messages being phased out in favor of improved
 replacements, is just over a hundred.)
 Flexible operational and error handing facilities are also, as usual,
 the bulk of the system.  Version numbering and tracking has proved to
 be quite important and merchant versioning is being added.

Eastlake, et al Informational [Page 50] RFC 1898 CyberCash Version 0.8 February 1996

 Use of text for messages has proven very beneficial.  This makes it
 possible to easily deal with messages using common everyday tools
 such as text editors and spead sheets.  Use of binary TLV (type,
 length, value) encoding or the like is certainly possible but imposes
 a significantly higher level of complexity on every tool that has to
 deal with the messages.
 Encryption and decryption impose some difficulties in development.
 Any confusion about decryption keys or algorithms will render
 encrypted material meaningless and tools are needed to provide
 decyrption for debugging outside of normal program operation.  But
 this pales compared with the stringencies imposed by signatures.  All
 parts of the system must have absolutely identical ideas as to the
 exact bit patterns to be hashed or signed and their exact order.
 Seemingly trivial differences in capitalization, punctuation,
 framing, order, or the like, in addition to any disagreement about
 keys or algorithms, will lead to frustrating failures of signatures
 to match.  Passing signatures through an intermediate system and
 checking them at a third system, as is done when a customer's
 signature is passed through a merchant and checked at the CyberCash
 server, compounds the problem.

6. Security Considerations

 The CyberCash Version 0.8 Credit Card system provides substantial
 protection to payment messages as described above in sections 1.2,
 2.2.4, and 2.2.5.  However, it provides no privacy to the shopping
 interaction which is essentially outside of its purview.  It also
 provides no protection against dishonest merchants other than those
 normally available with credit card purchases.  Care must be taken to
 avoid loss of control of the machines on which parts of this system
 runs or security may be compromised.
 Current credit card dispute  resolution  systems  require  deliberate
 bypasses be implemented for some of the security normally established
 by CyberCash as described in section 3.4.

References

 [ISO 4217] - Codes for the representation of currencies and funds
 [ISO 8583] - Financial transaction card originated messages -
 Interchange message specifications, 1993-12-15.
 [RFC 822] - Crocker, D., "Standard for the format of ARPA Internet
 text messages", STD 11, RFC 822, UDEL, August 1982.

Eastlake, et al Informational [Page 51] RFC 1898 CyberCash Version 0.8 February 1996

 [RFC 1521] - Borenstein, N., and N. Freed, "MIME (Multipurpose
 Internet Mail Extensions) Part One: Mechanisms for Specifying and
 Describing the Format of Internet Message Bodies", RFC 1521,
 Bellcore, Innosoft, September 1993.
 [RFC 1766] - Alvestrand, H., "Tags for the Identification of
 Languages", UNINETT, March 1995.

Authors' Addresses

 Donald E. Eastlake 3rd
 CyberCash, Inc.
 318 Acton Street
 Carlisle, MA 01741 USA
 Phone:   +1 508 287 4877
 EMail:   dee@cybercash.com
 Brian Boesch
 CyberCash, Inc.
 2100 Reston Parkway, Suite 430
 Reston, VA 22091 USA
 Phone:   +1 703-620-4200
 EMail:   boesch@cybercash.com
 Steve Crocker
 CyberCash, Inc.
 2100 Reston Parkway, Suite 430
 Reston, VA 22091 USA
 Phone:   +1 703-620-4200
 EMail:   crocker@cybercash.com
 Magdalena Yesil
 CyberCash, Inc.
 555 Twin Dolphin Drive, Suite 570
 Redwood City, CA 94065 USA
 Phone:   +1 415-594-0800
 EMail:   magdalen@cybercash.com

Eastlake, et al Informational [Page 52]

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