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Network Working Group                                       John Kelsey
Category: INTERNET-DRAFT                                       Certicom
draft-ietf-syslog-sign-03.txt
Expires Mar 2002                                             Jon Callas
September 2001                                 Wave Systems Corporation


                             Syslog-Sign Protocol
                        draft-ietf-syslog-sign-03.txt



Copyright Notice

   Copyright 2001 by The Internet Society. All Rights Reserved.

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."

       The list of current Internet-Drafts can be accessed at
            http://www.ietf.org/ietf/1id-abstracts.txt

       The list of Internet-Draft Shadow Directories can be accessed at
            http://www.ietf.org/shadow.html.

       This work is a product of the IETF syslog Working Group.  More
       information about this effort may be found at
         http://www.ietf.org/html.charters/syslog-charter.html

   Comments about this draft should be directed to the syslog working
   group at the mailing list of syslog-sec@employees.org.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.

Abstract

   This document describes syslog-sign, a mechanism adding origin
   authentication, message integrity, replay-resistance, message
   sequencing, and detection of missing messages to syslog.
   Syslog-sign provides these security features in a way that has

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   minimal requirements and minimal impact on existing syslog
   implementations.  It is possible to support syslog-sign and gain
   some of its security attributes by only changing the behavior of the
   devices generating syslog messages. Some additional processing of
   the received syslog messages and the syslog-sign messages on the
   relays and collectors may realize additional security benefits.















































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Table of Contents

          Copyright Notice                                            1
          Status of this Memo                                         1
          Abstract                                                    1
          Table of Contents                                           3
   1.     Introduction                                                4
   2.     Signature Block Format and Fields                           4
   2.1.   syslog Packets Containing a Signature Block                 4
   2.2.   Priority                                                    5
   2.3.   Cookie                                                      6
   2.4.   Version                                                     6
   2.5.   Reboot Session ID                                           6
   2.6.   Signature Group                                             6
   2.7.   Global Block Counter                                        6
   2.8.   First Message Number                                        6
   2.9.   Count                                                       7
   2.10.  Hash Block                                                  7
   2.11.  Signature                                                   7
   3.     Signature Groups                                            7
   4.     Payload and Certificate Blocks                              8
   4.1.   Preliminaries: Key Management and Distribution Issues       8
   4.2.   Building the Payload Block                                  9
   4.3.   Building the Certificate Block                             10
   5.     Redundancy and Flexibility                                 11
   5.1.   Redundancy                                                 11
   5.1.1. Certificate Blocks                                         11
   5.1.2. Signature Blocks                                           11
   5.2.   Flexibility                                                11
   6.     Efficient Verification of Logs                             12
   6.1.   Offline Review of Logs                                     12
   6.2.   Online Review of Logs                                      13
   7.     Security Considerations                                    14
   8.     IANA Considerations                                        15
   9.     Authors and Working Group Chair                            15
   10.    Acknowledgements                                           15
   11.    References                                                 15
   12.    Full Copyright Statement                                   16















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1. Introduction

   Syslog-sign is an enhancement to syslog [RFC3164] that adds origin
   authentication, message integrity, replay resistance, message
   sequencing, and detection of missing messages to syslog. This
   mechanism makes no changes to the syslog packet format but does
   require strict adherence to that format.  A syslog-sign message
   contains a signature block as the CONTENT field in the HEADER part
   as defined in Section 4 of [RFC3164].  This signature block contains
   a separate digital signature for each of a group of previously sent
   syslog messages.  The overall message is also signed as the last
   value in this message.

   Each signature block contains, in effect, a detached signature on
   some number of previously sent messages.  While most implementations
   of syslog involve only a single device as the generator of each
   message and a single receiver as the collector of each message,
   provisions need to be made to cover messages being sent to multiple
   receivers.  This is generally performed based upon the Priority
   value of the individual messages.  For example, messages from any
   Facility with a Severity value of 3, 2, 1 or 0 may be sent to one
   collector while all messages of Facilities 4, 10, 13, and 14 may be
   sent to another collector.  Appropriate syslog-sign messages must be
   kept with their proper syslog messages.  To address this,
   syslog-sign utilizes a signature-group.  A signature group
   identifies a group of messages that are all kept together for
   signing purposes by the device.  A signature block always belongs to
   exactly one signature group and it always signs messages belonging
   only to that signature group.

   The receiver of the previous messages may verify that the digital
   signature of each received message matches the signature contained
   in the signature block.  A collector may process these signature
   blocks as they arrive, building an authenticated log file.
   Alternatively, it may store all the log messages in the order they
   were received.  This allows a network operator to authenticate the
   log file at the time the logs are reviewed.

2. Signature Block Format and Fields

   Since the device generating the signature block message signs the
   entire syslog message, it is imperative that the message MUST NOT be
   changed in transit.  In adherence with Section 4 of [RFC3164], a
   fully formed syslog message containing a PRI part and a HEADER part
   containing TIMESTAMP and HOSTNAME fields MUST NOT be changed or
   modified by any relay.

2.1. syslog Packets Containing a Signature Block

   Signature block messages MUST be completely formed syslog messages.
   Signature block messages have PRI, HEADER, and MSG parts as
   described in Sections 4.1.1 and 4.1.3 of [RFC3164].  The PRI part

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   MUST have a valid Priority value bounded by angled brackets.  The
   HEADER part MUST have a valid TIMESTAMP field as well as a HOSTNAME
   field.  It SHOULD also contain a valid TAG field.  It is RECOMMENDED
   that the TAG field have the value of "syslog " (without the double
   quotes) to signify that this message was generated by the syslog
   process.  The CONTENT field of the syslog signature block messages
   have the following fields.

   The signature block is composed of the following fields.  Each field
   must be printable ASCII, and any binary values are base-64 encoded.


    Field                       Size in bytes
    -----                       ---- -- -----

    Priority                          3

    Cookie                            8

    Version                           4

    Reboot Session ID                 8

    Signature Group                   3

    Global Block Counter              8

    First Message Number              8

    Count                             2

    Hash Block              variable, size of hash

    Signature                     variable

   These fields are described below.

2.2. Priority

   The signature group priority field is set depending on the settings
   described in Section 3 below.  This field is 1, 2, or 3 characters
   in length and is terminated with a space character.  The value in
   this field specifies the version of the syslog-sign protocol and is
   terminated with a space character.  This is extensible to allow for
   different hash algorithms and signature schemes to be used in the
   future.  The value of this field is calculated by determining the
   base64 encoding of the protocol version, the hash algorithm and the
   signature scheme.

       Protocol Version - 2 bytes with the first version being the ABNF
       value of %b0000000000000001 to denote Version 1.


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       Hash Algorithm - 1 byte with the definition that %b00000001
       denotes SHA1.  [FIPS-180-1]

       Signature Scheme - 1 byte with the definition that %b00000001
       denotes OpenPGP DSA [RFC2440], [DSA94].

   As such, the version, hash algorithm and signature scheme may be
   represented as %h00010101.  The priority field will be the base64
   encoding of that value with a space character appended.

2.3. Cookie

   The cookie is a nine-byte sequence to signal that this is a
   signature block.  This sequence is "@#sigSIG " (without the double
   quotes).

2.4. Version

   The version is 2 bytes with the first version being the ABNF value
   of %b0000000000000001 to denote Version 1.

2.5. Reboot Session ID

   The reboot session ID is a 48-bit quantity encoded in base 64 as
   eight bytes, which is required to never repeat or decrease in the
   lifetime of the device.

2.6. Signature Group

   This is the SIG identifier, described above.  It may take on any
   value from 0-191 inclusive, and is encoded as two bytes in base 64.

2.7. Global Block Counter

   The global block counter is a 48-bit quantity encoded in base 64 as
   eight bytes, which is the number of signature blocks sent out by
   syslog-sign before this one, in this reboot session.  Note that this
   counter crosses signature groups; it allows us to roughly
   synchronize when two messages were sent, even though they went to
   different collectors.

2.8. First Message Number

   This is a 48-bit quantity encoded in base 64 as eight bytes, which
   is the unique message number within this signature group of the
   first message whose hash appears in this block.  (That is, if this
   signature group has processed 1000 messages so far, and the 1001st
   message from this signature group is the first one whose hash
   appears in this signature block, then this field is 1001.)




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2.9. Count

   The count is a 6-bit quantity encoded in base 64 as one byte, which
   is the number of message hashes to follow.

2.10. Hash Block

   The hash block is a block of hashes, each separately encoded in
   base-64.  The hashing algorithm used effectively specified by the
   Version field determines the size of each hash, but the size MUST
   NOT be shorter than 160 bits.

2.11. Signature

   This is a digital signature, encoded in base-64. The Version field
   effectively specifies the original encoding of the signature.

3. Signature Groups

   Recall that syslog-sign doesn't alter messages.  That means that the
   signature group of a message doesn't appear anywhere in the message
   itself.  Instead, the device and any intermediate relays use
   something inside the message to decide where to route it; the device
   needs to use the same information to decide which signature group a
   message belongs to.

   Syslog-sign provides four options for handling signature groups,
   linking them with PRI values.  In all cases, no more than 192
   signature groups (0-191) are permitted.  In this list, SIG is the
   signature group, and PRI is the PRI value of the signature and
   certificate blocks in that signature group.

    a. '0' -- Only one signature group, SIG = 0, PRI = XXX.  The same
       signature group is used for all certificate and signature
       blocks, and for all messages.

    b. '1' -- Each PRI value has its own signature group.  Signature
       and certificate blocks for a given signature group have SIG =
       PRI for that signature group.

    c. '2' -- Each signature group contains a range of PRI values.
       Signature groups are assigned sequentially.  A certificate or
       signature block for a given signature group have its SIG value,
       and the highest PRI value in that signature group.  (That is, if
       signature group 2 has PRI values in the range 100-191, then all
       signature group 2's signature and certificate blocks will have
       PRI=191, and SIG=2.

    d. '3' -- Signature groups are not assigned with any simple
       relationship to PRI values.  A certificate or signature block in
       a given signature group will have that group's SIG value, and
       PRI = XXX.

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   Note that options (a) and (b) make the SIG value redundant.
   However, in installations where log messages are forwarded to
   different collectors based on some complicated criteria (e.g.,
   whether the message text matches some regular expression), the SIG
   value gives an easy way for relays to decide where to route
   signature and certificate blocks.  This is necessary, since these
   blocks almost certainly won't match the regular expressions.

   Options (a) and (d) set the PRI value to XXX for all signature and
   certificate blocks.  This is intended to make it easier to process
   these syslog messages separately from others handled by a relay.
   One reasonable way to configure some installations is to have only
   one signature group, send messages to many collectors, but send a
   copy of each signature and certificate block to each collector.
   This won't allow any collector to detect gaps in the messages, but
   it will allow all messages that arrive at each collector to be put
   into the right order, and to be verified.

4. Payload and Certificate Blocks

   Certificate blocks and payload blocks provide key management in
   syslog-sign.

4.1. Preliminaries: Key Management and Distribution Issues

   The purpose of certificate blocks is to support key management using
   public key cryptosystems.  All devices send at least one certificate
   block at the beginning of a new reboot session, carrying useful
   information about the reboot session.

   There are three key points to understand about certificate blocks:

    a. They handle a variable-sized payload, fragmenting it if
       necessary and transmitting the fragments as legal syslog
       messages.  This payload is built (as described below) at the
       beginning of a reboot session and is transmitted in pieces with
       each certificate block carrying a piece.  Note that there is
       exactly one payload block per reboot session.

    b. The certificate blocks are digitally signed.  The device does
       not sign the payload block, but the signatures on the
       certificate blocks ensure its authenticity.  Note that it may
       not even be possible to verify the signature on the certificate
       blocks without the information in the payload block; in this
       case the payload block is reconstructed, the key is extracted,
       and then the certificate blocks are verified.  (This is
       necessary even when the payload block carries a certificate,
       since some other fields of the payload block aren't otherwise
       verified.)  In practice, I expect that most installations will
       keep the same public key over long periods of time, so that most
       of the time, it's easy to verify the signatures on the
       certificate blocks, and use the payload block to provide other

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       useful per-session information.

    c. The kind of payload block that is expected is determined by what
       kind of key material is on the collector that receives it.  The
       device and collector (or offline log viewer) has both some key
       material (such as a root public key, or predistributed public
       key), and an acceptable value for the Key Blob Type in the
       payload block, below.  The collector or offline log viewer MUST
       NOT accept a payload block of the wrong type.

4.2. Building the Payload Block

   The payload block is built when a new reboot session is started.
   There is a one-to-one correspondence of reboot sessions to payload
   blocks.  That is, each reboot session has only one payload block,
   regardless of how many signature groups it may support.

   The payload block consists of the following:

    a. Unique identifier of sender; by default, the sender's 128-bit IP
       address encoded in base-64.

    b. Full local timestamp for the device, including year if
       available, at time reboot session started.

    c. Signature Group Descriptor.  This consists of a one-character
       field specifying how signature groups are assigned. The
       possibilities are:

       (i) '0' -- Only one signature group supported.  For all
           signature blocks and certificate blocks, sig == pri == XXX.

      (ii) '1' -- Each pri value gets its own signature group.  For
           each signature/certificate block, sig == pri.

     (iii) '2' -- Signature groups are assigned in some way with no
           simple relationship to pri values; for all
           signature/certificate blocks, pri = XXX.

      (iv) '3' -- Signature groups are assigned to ranges of pri
           values.  For each signature/certificate block, pri = largest
           pri contained within that signature group.

    d. Highest SIG Value -- a two-byte field base 64 encoded, must be a
       number between 0 and 191, inclusive.

    e. Key Blob Type, a one-byte field which holds one of four values:

       (i) 'C' -- a PKIX certificate.




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      (ii) 'P' -- an OpenPGP certificate.

     (iii) 'K' -- the public key whose corresponding private key is
           being used to sign these messages.

      (iv) 'N' -- no key information sent; key is predistributed.

       (v) 'U' -- installation-specific key exchange information

    f. The key blob, consisting of the raw key data, if any, base-64
       encoded.

4.3. Building the Certificate Block

   The certificate block must get the payload block to the collector.
   Since certificates can legitimately be much longer than 1024 bytes,
   each certificate block carries a piece of the payload block.  Note
   that the device MAY make the certificate blocks of any legal length
   (that is, any length less than 1024 bytes) which will hold all the
   required fields.  Software that processes certificate blocks MUST
   deal correctly with blocks of any legal length.

   The certificate block is built as follows:

    a. A pri value           -- this variable-length (one, two, or
                                three byte) value is chosen to ensure
                                that every signature group will get a
                                full set of certificate blocks.

    b. Cookie                -- an eight byte string, "@#sigCer".

    c. Version               -- 12 bits base-64 encoded as two bytes.

    d. Reboot Session ID     -- as above, a 48-bit quantity encoded
                                in base 64 as eight bytes, which is
                                required to never repeat or decrease in
                                the lifetime of the device.

    e. Signature Group       -- 12 bits base-64 encoded as two bytes.

    f. Total Payload Length  -- 32 bits base-64 encoded as six bytes.

    g. Index into Payload    -- 32 bits base-64 encoded as six bytes.

    h. Fragment Length       -- 12 bits base-64 encoded as two bytes.

    i. Payload Fragment      -- a fragment of the payload, as specified
                                by the above fields.

    j. Signature             -- a digital signature on fields a-i.



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5. Redundancy and Flexibility

   There is a general rule that determines how redundancy works and
   what level of flexibility the device and collector have in message
   formats: in general, the device is allowed to send signature and
   certificate blocks multiple times, to send signature and certificate
   blocks of any legal length, to include fewer hashes in hash blocks,
   etc.

5.1. Redundancy

   Syslog messages are sent over unreliable transport, which means that
   they can be lost in transit.  However, the collector must receive
   signature and certificate blocks or many messages may not be able to
   be verified. Sending signature and certificate blocks multiple times
   provides redundancy; since the collector MUST ignore
   signature/certificate blocks it has already received and
   authenticated, the device can in principle change its redundancy
   level for any reason, without communicating this fact to the
   collector.

   Although the device isn't constrained in how it decides to send
   redundant signature and certificate blocks, or even in whether it
   decides to send along mutliple copies of normal syslog messages,
   here I define some redundancy parameters below which may be useful
   in controlling redundant transmission from the device to the
   collector.

5.1.1. Certificate Blocks

   certInitialRepeat = number of times each certificate block should be
   sent before the first message is sent.

   certResendDelay  = maximum time delay in seconds to delay before
   next redundant sending.

   certResendCount  = maximum number of sent messages to delay before
   next redundant sending.

5.1.2. Signature Blocks

   sigNumberResends = number of times a signature block is resent.

   sigResendDelay   = maximum time delay in seconds from original
   sending to next redundant sending.

   sigResendCount   = maximum number of sent messages to delay before
   next redundant sending.

5.2. Flexibility

   The device may change many things about the makeup of signature and

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   certificate blocks in a given reboot session. The things it cannot
   change are:

     * The version

     * The number or arrangements of signature groups

   It is legitimate for a device to send our short signature blocks, in
   order to keep the collector able to verify messages quickly.  In
   general, unless something verified by the payload block or
   certificate blocks is changed within the reboot session ID, any
   change is allowed to the signature or certificate blocks during the
   session.  The device may send shorter signature and certificate
   blocks for

6. Efficient Verification of Logs

   The logs secured with syslog-sign may either be reviewed online or
   offline.  Online review is somewhat more complicated and
   computationally expensive, but not prohibitively so.

6.1. Offline Review of Logs

   When the collector stores logs and reviewed later, they can be
   authenticated offline just before they are reviewed.  Reviewing
   these logs offline is simple and relatively cheap in terms of
   resources used, so long as there is enough space available on the
   reviewing machine.  Here, we will consider that the stored log files
   have already been separated by sender, reboot session ID, and
   signature group.  This can be done very easily with a script file.
   We then do the following:

    a. First, we go through the raw log file, and split its contents
       into three files.  Each message in the raw log file is
       classified as a normal message, a signature block, or a
       certificate block.  Certificate blocks and signature blocks are
       stored in their own files.  Normal messages are stored in a
       keyed file, indexed on their hash values.

    b. We sort the certificate block file by index value, and check to
       see if we have a set of certificate blocks that can reconstruct
       the payload block.  If so, we reconstruct the payload block,
       verify any key-identifying information, and then use this to
       verify the signatures on the certificate blocks we've received.
       When this is done, we have verified the reboot session and key
       used for the rest of the process.

    c. We sort the signature block file by firstMessageNumber.  We now
       create an authenticated log file, which will consist of some
       header information, and then a sequence of message number,
       message text pairs.  We next go through the signature block
       file.  For each signature block in the file, we do the

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       following:

       (i) Verify the signature on the block.

      (ii) For each hashed message in the block:

           (a) Look up the hash value in the keyed message file.

           (b) If the message is found, write (message number, message
               text) to the authenticated log file.

     (iii) Skip all other signature blocks with the same
           firstMessageNumber.

    d. The resulting authenticated log file will contain all messages
       that have been authenticated, and will indicate (by missing
       message numbers) all gaps in the authenticated messages.

   It's pretty easy to see that, assuming sufficient space for building
   the keyed file, this whole process is linear in the number of
   messages (generally two seeks, one to write and the other to read,
   per normal message received), and O(N lg N) in the number of
   signature blocks.  This estimate comes with two caveats: first, the
   signature blocks will arrive very nearly in sorted order, and so can
   probably be sorted more cheaply on average than O(N lg N) steps.
   Second, the signature verification on each signature block will
   almost certainly be more expensive than the sorting step in
   practice.  We haven't discussed error-recovery, which may be
   necessary for the certificate blocks.  In practice, a very simple
   error-recovery strategy is probably good enough -- if the payload
   block doesn't come out as valid, then we can just try an alternate
   instance of each certificate block, if such are available, until we
   get the payload block right.

   It's easy for an attacker to flood us with plausible-looking
   messages, signature blocks, and certificate blocks.

6.2. Online Review of Logs

   Some processes on the collector machine may need to monitor log
   messages in something very close to real-time.  This can be done
   with syslog-sign, though it is somewhat more complex than the
   offline analysis.  This is done as follows:

    a. We have an output queue, into which we write (message number,
       message text) pairs which have been authenticated.  Again, we'll
       assume we're handling only one signature group, and only one
       reboot session ID, at any given time.

    b. We have three data structures: A queue into which (message
       number, hash of message) pairs is kept in sorted order, a queue
       into which (arrival sequence, hash of message) is kept in sorted

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       order, and a hash table which stores (message text, count)
       indexed by hash value.  In this file, count may be any number
       greater than zero; when count is zero, the entry in the hash
       table is cleared.

    c. We must receive all the certificate blocks before any other
       processing can really be done.  (This is why they're sent
       first.)  Once that's done, any certificate block that arrives is
       discarded.

    d. Whenever a normal message arrives, we add (arrival sequence,
       hash of message) to our message queue.  If our hash table has an
       entry for the message's hash value, we increment its count by
       one; otherwise, we create a new entry with count = 1.  When the
       message queue is full, we roll the oldest messages off the queue
       by taking the last entry in the queue, and using it to index the
       hash table.  If that entry has count is 1, we delete the entry
       in the hash table; otherwise, we decrement its count.  We then
       delete the last entry in the queue.

    e. Whenever a signature block arrives, we first check to see if the
       firstMessageNumber value is too old, or if another signature
       block with that firstMessageNumber has already been received.
       If so, we discard the signature block unread.  Otherwise, we
       check its signature, and discard it if the signature isn't
       valid.  A signature block contains a sequence of (message
       number, message hash) pairs.  For each pair, we first check to
       see if the message hash is in the hash table.  If so, we write
       out the (message number, message text) in the authenticated
       message queue.  Otherwise, we write the (message number, message
       hash) to the message number queue.  This generally involves
       rolling the oldest entry out of this queue: before this is done,
       that entry's hash value is again searched for in the hash table.
        If a matching entry is found, the (message number, message
       text) pair is written out to the authenticated message queue.
       In either case, the oldest entry is then discarded.

    f. The result of this is a sequence of messages in the
       authenticated message queue, each of which has been
       authenticated, and which are combined with numbers showing their
       order of original transmission.

   It's not too hard to see that this whole process is roughly linear
   in the number of messages, and also in the number of signature
   blocks received.  The process is susceptible to flooding attacks; an
   attacker can send enough normal messages that the messages roll off
   their queue before their signature blocks can be processed.

7. Security Considerations

     * As with any technology involving cryptography, you should check
       the current literature to determine if any algorithms used here

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       have been found to be vulnerable to attack.

     * This specification uses Public Key Cryptography technologies.
       The proper party or parties must control the private key portion
       of a public-private key pair.

     * Certain operations in this specification involve the use of
       random numbers.  An appropriate entropy source should be used to
       generate these numbers.  See [RFC1750].

8. IANA Considerations

   As specified in this document, the Priority field contains options
   for a hash algorithm and signature scheme. Values of zero are
   reserved. A value of 1 is defined to be SHA-1, and OpenPGP-DSA,
   respectively. Values 2 through 63 are to be assigned by IANA using
   the "IETF Consensus" policy defined in RFC2434. Capability Code
   values 64 through 127 are to be assigned by IANA, using the "First
   Come First Served" policy defined in RFC2434. Capability Code values
   128 through 255 are vendor-specific, and values in this range are
   not to be assigned by IANA.

9. Authors and Working Group Chair

   The working group can be contacted via the current chair:

       Chris Lonvick
       Cisco Systems
       Email: clonvick@cisco.com

   The authors of this draft are:

       John Kelsey
       Email: kelsey.j@ix.netcom.com

       Jon Callas
       Email: jon@callas.org

10. Acknowledgements

   The authors wish to thank Alex Brown, Chris Calabrese, Carson
   Gaspar, Drew Gross, Chris Lonvick, Darrin New, Marshall Rose, Holt
   Sorenson, Rodney Thayer, and the many Counterpane Internet Security
   engineering and operations people who commented on various versions
   of this proposal.

11. References

   [DSA94]         NIST, FIPS PUB 186, "Digital Signature Standard",
                   May 1994.



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   [FIPS-180-1]    "Secure Hash Standard", National Institute of
                   Standards and Technology, U.S. Department Of
                   Commerce, April 1995.

                   Also known as: 59 Fed Reg 35317 (1994).

   [MENEZES]       Alfred Menezes, Paul van Oorschot, and Scott
                   Vanstone, "Handbook of Applied Cryptography," CRC
                   Press, 1996.

   [RFC1750]       D. Eastlake, S. Crocker, and J. Schiller,
                   "Randomness Recommendations for Security", RFC
                   1750, December 1994.

   [RFC1983]       Malkin, G., "Internet Users' Glossary", FYI 18, RFC
                   1983, August 1996.

   [RFC2085]       M. Oehler and R. Glenn, "HMAC-MD5 IP Authentication
                   with Replay Prevention", RFC 2085, February 1997.

   [RFC2104]       H. Krawczyk, M. Bellare, and R. Canetti, "HMAC:
                   Keyed-Hashing for Message Authentication", RFC 2104
                   February 1997.

   [RFC2119]       Bradner, S., "Key words for use in RFCs to Indicate
                   Requirement Level", BCP 14, RFC 2119, March 1997.

   [RFC2434]       T. Narten and H. Alvestrand, "Guidelines for
                   Writing an IANA Considerations Section in RFCs",
                   RFC 2434, October 1998

   [RFC2440]       J. Callas, L. Donnerhacke, H. Finney, and R.
                   Thayer,"OpenPGP Message Format", RFC 2440, November
                   1998.

   [RFC3164]       C. Lonvick, "The BSD Syslog Protocol", RFC 3164,
                   August 2001.

   [SCHNEIER]      Schneier, B., "Applied Cryptography Second Edition:
                   protocols, algorithms, and source code in C", 1996.

   [SYSLOG-REL]    D. New, M. Rose, "Reliable Delivery for syslog",
                   work in progress.

12. Full Copyright Statement

   Copyright 2001 by The Internet Society. All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any

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   kind, provided that the above copyright notice and this paragraph
   are included on all such copies and derivative works. However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


































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