





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.







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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



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      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.






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   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






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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



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   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



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   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.






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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



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   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.





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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.



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   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:



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    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.



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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.





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   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==



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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



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   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.




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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



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          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



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   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:




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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



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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]

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   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



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       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:




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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
   $$-CyberCash-End-kchfiZ5WAUlpk1/v1ogwuQ==-$$

   #####################################################################



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   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



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   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



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       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.



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   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.





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   [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







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