Network Working Group John Kelsey
Category: INTERNET-DRAFT Certicom
draft-ietf-syslog-sign-02.txt
Expires Mar 2002 Jon Callas
September 2001 Wave Systems Corporation
Syslog-Sign Protocol
draft-ietf-syslog-sign-02.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 6
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 10
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 CONTEXT field in the MSG part as
defined in Section 4.2.2 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 4.1 of [RFC3164], a
fully formed syslog message containing a PRI part and a MSG 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 a PRI part and a MSG part as described
in Sections 4.1.1 and 4.1.3 of [RFC3164]. The PRI part MUST have a
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valid Priority value bounded by angled brackets. The MSG 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
CONTEXT field of the syslog signature block messages have the
following fields.
The signature block is composed of the following fields. Recall
that every field must be printable ASCII, and any binary values are
base-64 encoded.
a. PRI (3)
b. Cookie (8)
c. Version (4)
d. Reboot Session ID (8)
e. Signature Group (3)
f. Global Block Counter (8)
g. First Message Number (8)
h. Count (2)
i. Hash Block (variable, size of hash)
j. 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.
Hash Algorithm - 1 byte with the definition that %b00000001
denotes SHA1. [FIPS-180-1]
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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.)
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.
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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.
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
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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
useful per-session information.
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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.
(ii) 'P' -- an OpenPGP certificate.
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(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 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 -- a 12-bit field encoded in base-64 as two bytes.
d. Reboot Session ID -- as above.
e. Signature Group -- a 12-bit field encoded in base-64 as two
bytes.
f. Total Payload Length -- a 32-bit field encoded in base-64 as six
bytes.
g. Index into Payload -- a 32-bit field encoded in base-64 as six
bytes.
h. Fragment Length -- a 12-bit field encoded in base-64 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.
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
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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
certificate blocks in a given reboot session. The things it cannot
change are:
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* 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
following:
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(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
order, and a hash table which stores (message text, count)
indexed by hash value. In this file, count may be any number
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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
have been found to be vulnerable to attack.
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* 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.
[FIPS-180-1] "Secure Hash Standard", National Institute of
Standards and Technology, U.S. Department Of
Commerce, April 1995.
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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
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document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Kelsey, Callas Expires March 9, 2002 [Page 16]
INTERNET-DRAFT Syslog-Sign Protocol September 9, 2001
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
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