idnits 2.17.1 draft-ietf-syslog-sign-18.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** It looks like you're using RFC 3978 boilerplate. You should update this to the boilerplate described in the IETF Trust License Policy document (see https://trustee.ietf.org/license-info), which is required now. -- Found old boilerplate from RFC 3978, Section 5.1 on line 18. -- Found old boilerplate from RFC 3978, Section 5.5 on line 1230. -- Found old boilerplate from RFC 3979, Section 5, paragraph 1 on line 1207. -- Found old boilerplate from RFC 3979, Section 5, paragraph 2 on line 1214. -- Found old boilerplate from RFC 3979, Section 5, paragraph 3 on line 1220. ** This document has an original RFC 3978 Section 5.4 Copyright Line, instead of the newer IETF Trust Copyright according to RFC 4748. ** This document has an original RFC 3978 Section 5.5 Disclaimer, instead of the newer disclaimer which includes the IETF Trust according to RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. ** There are 3 instances of too long lines in the document, the longest one being 2 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (May 25, 2006) is 6539 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: '3' is defined on line 1111, but no explicit reference was found in the text == Unused Reference: '4' is defined on line 1114, but no explicit reference was found in the text == Unused Reference: '6' is defined on line 1120, but no explicit reference was found in the text == Unused Reference: '7' is defined on line 1123, but no explicit reference was found in the text == Unused Reference: '9' is defined on line 1129, but no explicit reference was found in the text == Unused Reference: '10' is defined on line 1131, but no explicit reference was found in the text == Unused Reference: '11' is defined on line 1135, but no explicit reference was found in the text == Unused Reference: '12' is defined on line 1138, but no explicit reference was found in the text == Unused Reference: '14' is defined on line 1144, but no explicit reference was found in the text == Unused Reference: '15' is defined on line 1147, but no explicit reference was found in the text == Unused Reference: '16' is defined on line 1150, but no explicit reference was found in the text == Unused Reference: '22' is defined on line 1169, but no explicit reference was found in the text == Unused Reference: '25' is defined on line 1179, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. '1' -- Possible downref: Non-RFC (?) normative reference: ref. '2' -- Possible downref: Non-RFC (?) normative reference: ref. '3' -- Possible downref: Non-RFC (?) normative reference: ref. '4' ** Obsolete normative reference: RFC 1750 (ref. '8') (Obsoleted by RFC 4086) ** Downref: Normative reference to an Informational RFC: RFC 1983 (ref. '9') ** Downref: Normative reference to an Informational RFC: RFC 2104 (ref. '12') ** Obsolete normative reference: RFC 2279 (ref. '14') (Obsoleted by RFC 3629) ** Obsolete normative reference: RFC 2234 (ref. '15') (Obsoleted by RFC 4234) ** Obsolete normative reference: RFC 2373 (ref. '16') (Obsoleted by RFC 3513) ** Obsolete normative reference: RFC 2434 (ref. '17') (Obsoleted by RFC 5226) ** Obsolete normative reference: RFC 2440 (ref. '18') (Obsoleted by RFC 4880) ** Obsolete normative reference: RFC 2574 (ref. '19') (Obsoleted by RFC 3414) ** Obsolete normative reference: RFC 3164 (ref. '20') (Obsoleted by RFC 5424) ** Obsolete normative reference: RFC 3548 (ref. '23') (Obsoleted by RFC 4648) == Outdated reference: A later version (-23) exists of draft-ietf-syslog-protocol-16 -- Possible downref: Non-RFC (?) normative reference: ref. '25' Summary: 16 errors (**), 0 flaws (~~), 17 warnings (==), 12 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 syslog Working Group J. Kelsey 3 Internet-Draft 4 Expires: November 26, 2006 J. Callas 5 PGP Corporation 6 A. Clemm 7 Cisco Systems 8 May 25, 2006 10 Signed syslog Messages 11 draft-ietf-syslog-sign-18.txt 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that any 16 applicable patent or other IPR claims of which he or she is aware 17 have been or will be disclosed, and any of which he or she becomes 18 aware will be disclosed, in accordance with Section 6 of BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF), its areas, and its working groups. Note that 22 other groups may also distribute working documents as Internet- 23 Drafts. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/ietf/1id-abstracts.txt. 33 The list of Internet-Draft Shadow Directories can be accessed at 34 http://www.ietf.org/shadow.html. 36 This Internet-Draft will expire on November 26, 2006. 38 Copyright Notice 40 Copyright (C) The Internet Society (2006). 42 Abstract 44 This document describes a mechanism to add origin authentication, 45 message integrity, replay-resistance, message sequencing, and 46 detection of missing messages to the transmitted syslog messages. 47 This specification draws upon the work defined in RFC xxx, "The 48 syslog Protocol", however it may be used atop any message delivery 49 mechanism, even that defined in RFC 3164, "The BSD syslog Protocol", 50 or in the RAW mode of "RFC 3195, "The Reliable Delivery of syslog". 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 2. Conventions Used in this Document . . . . . . . . . . . . . . 6 56 3. syslog Message Format . . . . . . . . . . . . . . . . . . . . 7 57 4. Signature Block Format and Fields . . . . . . . . . . . . . . 8 58 4.1. syslog Packets Containing a Signature Block . . . . . . . 8 59 4.2. Version . . . . . . . . . . . . . . . . . . . . . . . . . 9 60 4.3. Reboot Session ID . . . . . . . . . . . . . . . . . . . . 9 61 4.4. Signature Group and Signature Priority . . . . . . . . . . 9 62 4.5. Global Block Counter . . . . . . . . . . . . . . . . . . . 11 63 4.6. First Message Number . . . . . . . . . . . . . . . . . . . 11 64 4.7. Count . . . . . . . . . . . . . . . . . . . . . . . . . . 12 65 4.8. Hash Block . . . . . . . . . . . . . . . . . . . . . . . . 12 66 4.9. Signature . . . . . . . . . . . . . . . . . . . . . . . . 12 67 5. Payload and Certificate Blocks . . . . . . . . . . . . . . . . 13 68 5.1. Preliminaries: Key Management and Distribution Issues . . 13 69 5.2. Building the Payload Block . . . . . . . . . . . . . . . . 14 70 5.3. Building the Certificate Block . . . . . . . . . . . . . . 14 71 5.3.1. Version . . . . . . . . . . . . . . . . . . . . . . . 15 72 5.3.2. Reboot Session ID . . . . . . . . . . . . . . . . . . 15 73 5.3.3. Signature Group and Signature Priority . . . . . . . . 16 74 5.3.4. Total Payload Block Length . . . . . . . . . . . . . . 16 75 5.3.5. Index into Payload Block . . . . . . . . . . . . . . . 16 76 5.3.6. Fragment Length . . . . . . . . . . . . . . . . . . . 16 77 5.3.7. Signature . . . . . . . . . . . . . . . . . . . . . . 16 78 6. Redundancy and Flexibility . . . . . . . . . . . . . . . . . . 17 79 6.1. Redundancy . . . . . . . . . . . . . . . . . . . . . . . . 17 80 6.1.1. Certificate Blocks . . . . . . . . . . . . . . . . . . 17 81 6.1.2. Signature Blocks . . . . . . . . . . . . . . . . . . . 17 82 6.2. Flexibility . . . . . . . . . . . . . . . . . . . . . . . 18 83 7. Efficient Verification of Logs . . . . . . . . . . . . . . . . 19 84 7.1. Offline Review of Logs . . . . . . . . . . . . . . . . . . 19 85 7.2. Online Review of Logs . . . . . . . . . . . . . . . . . . 20 86 8. Security Considerations . . . . . . . . . . . . . . . . . . . 22 87 8.1. Cryptography Constraints . . . . . . . . . . . . . . . . . 22 88 8.2. Packet Parameters . . . . . . . . . . . . . . . . . . . . 22 89 8.3. Message Authenticity . . . . . . . . . . . . . . . . . . . 23 90 8.4. Sequenced Delivery . . . . . . . . . . . . . . . . . . . . 23 91 8.5. Replaying . . . . . . . . . . . . . . . . . . . . . . . . 23 92 8.6. Reliable Delivery . . . . . . . . . . . . . . . . . . . . 23 93 8.7. Sequenced Delivery . . . . . . . . . . . . . . . . . . . . 23 94 8.8. Message Integrity . . . . . . . . . . . . . . . . . . . . 24 95 8.9. Message Observation . . . . . . . . . . . . . . . . . . . 24 96 8.10. Man In The Middle . . . . . . . . . . . . . . . . . . . . 24 97 8.11. Denial of Service . . . . . . . . . . . . . . . . . . . . 24 98 8.12. Covert Channels . . . . . . . . . . . . . . . . . . . . . 24 99 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 100 9.1. Version Field . . . . . . . . . . . . . . . . . . . . . . 26 101 9.2. SIG Field . . . . . . . . . . . . . . . . . . . . . . . . 28 102 9.3. Key Blob Type . . . . . . . . . . . . . . . . . . . . . . 28 103 10. Authors and Working Group Chair . . . . . . . . . . . . . . . 29 104 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30 105 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30 106 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 32 107 Intellectual Property and Copyright Statements . . . . . . . . . . 33 109 1. Introduction 111 This document describes a mechanism that adds origin authentication, 112 message integrity, replay resistance, message sequencing, and 113 detection of missing messages to syslog. Essentially, this is 114 accomplished by sending a special syslog message. The contents of 115 this syslog message is called a Signature Block. Each Signature 116 Block contains, in effect, a detached signature on some number of 117 previously sent messages. It is cryptographically signed and 118 contains the hashes of previously sent syslog messages. 120 While most implementations of syslog involve only a single device as 121 the generator of each message and a single receiver as the collector 122 of each message, provisions need to be made to cover situations in 123 which messages are sent to multiple receivers. This concerns in 124 particular situations in which different messages are sent to 125 different receivers, meaning that some messages are sent to some 126 receivers but not to others. The required differentiation of 127 messages is generally performed based on the Priority value of the 128 individual messages. For example, messages from any Facility with a 129 Severity value of 3, 2, 1 or 0 may be sent to one collector while all 130 messages of Facilities 4, 10, 13, and 14 may be sent to another 131 collector. Appropriate syslog-sign messages must be kept with their 132 proper syslog messages. To address this, syslog-sign uses a 133 signature-group. A signature group identifies a group of messages 134 that are all kept together for signing purposes by the device. A 135 Signature Block always belongs to exactly one signature group and it 136 always signs messages belonging only to that signature group. 138 Additionally, a device will send a Certificate Block to provide key 139 management information between the sender and the receiver. This 140 Certificate Block has a field to denote the type of key material 141 which may be such things as a PKIX certificate, an OpenPGP 142 certificate, or even an indication that a key had been 143 predistributed. In the cases of certificates being sent, the 144 certificates may have to be split across multiple packets. 146 The receiver of the previous messages may verify that the digital 147 signature of each received message matches the signature contained in 148 the Signature Block. A collector may process these Signature Blocks 149 as they arrive, building an authenticated log file. Alternatively, 150 it may store all the log messages in the order they were received. 151 This allows a network operator to authenticate the log file at the 152 time the logs are reviewed. 154 This specification is independent of the actual transport protocol 155 selected. The best application of this mechanism will be to use it 156 with the syslog protocol as defined in RFC xxxx [24] as it utilizes 157 the STRUCTURED-DATA elements defined in that document. It may be 158 used with syslog packets over traditional UDP [5] as described in RFC 159 3164 [20]. It may also be used with the Reliable Delivery of syslog 160 as described in RFC 3195 [21], and it may be used with other message 161 delivery mechanisms. Other efforts to define event notification 162 messages should consider this specification in their design. 164 2. Conventions Used in this Document 166 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 167 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" that 168 appear in this document are to be interpreted as described in RFC 169 2119 [13]. 171 3. syslog Message Format 173 This specification does not rely upon any specific syslog message 174 format. It is RECOMMENDED to be used within the syslog protocol as 175 defined in RFC xxxx [24]. It MAY be transported over a traditional 176 syslog message format such as that defined in the informational RFC 177 3164 [20], or it MAY be used over the Reliable Delivery of syslog 178 Messages as defined in RFC 3195 [21]. Care must be taken when 179 choosing a transport for this mechanism, however. Since the device 180 generating the Signature Block message signs each message in its 181 entirety, it is imperative that the messages MUST NOT be changed in 182 transit. It is equally imperative that the syslog-sign messages MUST 183 NOT be changed in transit. Specifically, a relay as described in RFC 184 3164 MAY make changes to a syslog packet if specific fields are not 185 found. If this occurs, the entire mechanism described in this 186 document is rendered useless. 188 For convenience, this document will use the syslog message format in 189 the terms described in RFC xxxx [24]. Along with the other fields, 190 that document describes the concept of STRUCTURED DATA. STRUCTURED 191 DATA is defined in the form of SD ELEMENTS(SDEs). An SDE consists of 192 a name and parameter name - value pairs. The name is referred to as 193 SD-ID. The name-value pairs are referred to as SD-PARAM, or SD 194 Parameters, with the name constituting the SD-PARAM-NAME, the value 195 constituting the SD-PARAM-VALUE. This document defines the way to 196 use SDEs to convey the signing of syslog messages. The MSG part of 197 the syslog message as defined in RFC xxxx [24] will simply be empty - 198 it is not intended for interpretation by humans but by applications 199 that use those messages to build an authenticated log. Having said 200 that, as stated above, this mechanism should be considered to be 201 independent of the SD-ID definitions and the fields defined here 202 should be considered to be applicable to other message transports. 203 When used in conjunction with a syslog message format other than the 204 one defined in RFC xxxx [24], the format of the message payload will 205 simply happen to follow SDE format. 207 4. Signature Block Format and Fields 209 This section describes the Signature Block format and the fields used 210 within the Signature Block. 212 4.1. syslog Packets Containing a Signature Block 214 Signature Block messages MUST be encompassed within completely formed 215 syslog messages. It SHOULD also contain valid APP-NAME, PROCID, and 216 MSGID fields when used with RFC xxxx [24]. Similarly, it SHOULD 217 contain a valid TAG field when used with traditional syslog [20]. In 218 the latter case, it is RECOMMENDED that the TAG field have the value 219 of "syslog " (without the double quotes) to signify that this message 220 was generated by the syslog process. The CONTENT field of the syslog 221 Signature Block messages MUST be encoded as an SD ELEMENT, as defined 222 in RFC xxxx [24]. 224 The SD-ID must have the value of "ssign". 226 The SDE contains the fields of the Signature Block encoded as SD 227 Parameters, as specified in the following. The Signature Block is 228 composed of the following fields. The value of each field must be 229 printable ASCII, and any binary values are base 64 encoded, as 230 defined in RFC 3548 [23]. 232 Field SD-PARAM-NAME Size in bytes 233 ----- ------------- ---- -- ----- 235 Version VER 4 237 Reboot Session ID RSID 1-10 239 Signature Group SG 1 241 Signature Priority SPRI 1-3 243 Global Block Counter GBC 1-10 245 First Message Number FMN 1-10 247 Count CNT 1-2 249 Hash Block HB variable, size of hash 250 (base 64 encoded binary) 252 Signature SIGN variable 253 (base 64 encoded binary) 255 A Signature Block is accordingly encoded as follows (xxx denoting a 256 placeholder for the particular value: 258 "[ssign VER=xxx RSID=xxx SG=xxx SPRI=xxx GBC=xxx FMN=xxx CNT=xxx 259 HB=xxx SIGN=xxx]". 261 The fields are described below. 263 4.2. Version 265 The signature group version field is 4 characters in length and is 266 terminated with a space character. The value in this field specifies 267 the version of the syslog-sign protocol. This is extensible to allow 268 for different hash algorithms and signature schemes to be used in the 269 future. The value of this field is the grouping of the protocol 270 version (2 bytes), the hash algorithm (1 byte) and the signature 271 scheme (1 byte). 273 Protocol Version - 2 bytes with the first version as described in 274 this document being value of 01 to denote Version 1. 276 Hash Algorithm - 1 byte with the definition that 1 denotes SHA1 as 277 defined in FIPS-180-1.1995 [2]. 279 Signature Scheme - 1 byte with the definition that 1 denotes 280 OpenPGP DSA - RFC 2440 [18], FIPS.186-1.1998 [1]. 282 As such, the version, hash algorithm and signature scheme defined in 283 this document may be represented as "0111" (without the quote marks). 285 4.3. Reboot Session ID 287 The reboot session ID is a value between 1 and 10 bytes. The 288 acceptable values for this are between 0 and 9999999999. A reboot 289 session ID is expected to increase whenever a device reboots in order 290 to allow receivers to uniquely distinguish messages and message 291 signatures across reboots. A device needs to hence support 292 persisting previous reboot session ID across reboots. In cases where 293 a device does not support this capability, the reboot session ID MUST 294 always be set to a value of 0. Otherwise, it MUST increase whenever 295 a device reboots, starting with a value of 1. If the value latches 296 at 9999999999, then manual intervention may be required to reset it 297 to 0. Implementors MAY wish to consider using the snmpEngineBoots 298 value as a source for this counter as defined in RFC 2574 [19]. 300 4.4. Signature Group and Signature Priority 302 The SG identifier as described above may take on any value from 0-3 303 inclusive. The SPRI may take any value from 0-191. These fields 304 taken together allows network administrators to associate groupings 305 of syslog messages with appropriate Signature Blocks and Certificate 306 Blocks. For example, in some cases, network administrators may send 307 syslog messages of Facilities 0 through 15 to one destination while 308 sending messages with Facilities 16 through 23 to another. 309 Associated Signature Blocks should be sent to these different syslog 310 servers as well. 312 In some cases, an administrator may wish the Signature Blocks to go 313 to the same destination as the syslog messages themselves. This may 314 be to different syslog servers if the destinations of syslog messages 315 is being controlled by the Facilities or the Severities of the 316 messages. In other cases, administrators may wish to send the 317 Signature Blocks to an altogether different destination. 319 Syslog-sign provides four options for handling signature groups, 320 linking them with PRI values so they may be routed to the destination 321 commensurate with the appropriate syslog messages. In all cases, no 322 more than 192 signature groups (0-191) are permitted. The signature 323 group field indicates how to interpret the signature priority field. 324 The signature priority field contains information about the signature 325 group that the Signature Block pertains to. (Note the distinction 326 between signature group and signature group field: The signature 327 group that the Signature Block pertains to is indicated by the 328 signature priority (SPRI) field. The signature group field (SG) does 329 not indicate a signature group, but how to correctly interpret the 330 SPRI field.) 332 a. '0' -- There is only one signature group. All Signature Block 333 messages use a single PRI value which is the same SPRI value. In 334 this case, the administrators want all Signature Blocks to be 335 sent to a single destination; the Signature Block signs all 336 messages regardless of their PRI value. In all likelihood, all 337 of the syslog messages will also be going to that same 338 destination. 340 b. '1' -- Each PRI value has its own signature group. Signature 341 Blocks for a given signature group have SPRI = PRI for that 342 signature group. In this case, the administrator of a device may 343 not know where any of the syslog messages will ultimately go. 344 This use ensures that a Signature Block follows each of the 345 syslog messages to each destination. The SPRI correspondsss to 346 the identifier of the signature group, coinciding with the PRI 347 value of each of the signed syslog messages. 349 c. '2' -- Each signature group contains a range of PRI values. 350 Signature groups are assigned sequentially. A Signature Block 351 for a given signature group has its own SPRI value denoting the 352 highest PRI value in that signature group. For flexibility, the 353 PRI does not have to be that upper-boundary SPRI value. 355 d. '3' -- Signature groups are not assigned with any simple 356 relationship to PRI values. This has to be some predefined 357 arrangement between the sender and the intended receivers, 358 requiring configuration by a system administrator. 360 One reasonable way to configure some installations is to have only 361 one signature group with SIG=0. The devices send messages to many 362 collectors and also send a copy of each Signature Block to each 363 collector. This won't allow any collector to detect gaps in the 364 messages, but it allows all messages that arrive at each collector to 365 be put into the right order, and to be verified. It also allows each 366 collector to detect duplicates and any messages that are not 367 associated with a Signature Block. 369 4.5. Global Block Counter 371 The global block counter is a value representing the number of 372 Signature Blocks sent out by syslog-sign before this one, in this 373 reboot session. This takes at least 1 byte and at most 10 bytes 374 displayed as a decimal counter and the acceptable values for this are 375 between 0 and 9999999999. If the value latches at 9999999999, then 376 the reboot session counter must be incremented by 1 and the global 377 block counter resumes at 0. Note that this counter crosses signature 378 groups; it allows us to roughly synchronize when two messages were 379 sent, even though they went to different collectors. 381 In case a device does not support an incrementing reboot session ID 382 (that is, the value of the reboot session ID is 0), a device MAY 383 reset the global block counter to 0 after a reboot occurs. Note that 384 in this case, applications need to apply extra consideration when 385 authenticating a log, and situations in which reboots occur 386 frequently may result in losing the ability to verify the proper 387 sequence in which messages were sent and hence jeopardizing integrity 388 of the log. 390 4.6. First Message Number 392 This is a value between 1 and 10 bytes. It contains the unique 393 message number within this signature group of the first message whose 394 hash appears in this block. The very first message of the reboot 395 session will be numbered "1". 397 For example, if this signature group has processed 1000 messages so 398 far and message number 1001 is the first message whose hash appears 399 in this Signature Block, then this field contains 1001. 401 4.7. Count 403 The count is a 1 or 2 byte field displaying the number of message 404 hashes to follow. The valid values for this field are between 1 and 405 99. Note that the number of hashes that are included in the 406 Signature Block MUST be chosen such that the length of the resulting 407 syslog message does not exceed the maximum permissable syslog message 408 length. 410 4.8. Hash Block 412 The hash block is a block of hashes, each separately encoded in base 413 64. Each hash in the hash block is the hash of the entire syslog 414 message represented by the hash. The hashing algorithm used 415 effectively specified by the Version field determines the size of 416 each hash, but the size MUST NOT be shorter than 160 bits. It is 417 base 64 encoded as per RFC 2045. 419 4.9. Signature 421 This is a digital signature, encoded in base 64, as per RFC 2045. 422 The signature is calculated over all fields but excludes the space 423 characters between them. The Version field effectively specifies the 424 original encoding of the signature. The signature is a signature 425 over the entire data, including all of the PRI, HEADER, and hashes in 426 the hash block. To reiterate, the signature is calculated over the 427 completely formatted syslog-message, excluding spaces between fields, 428 and also excluding this signature field (the value of the signature 429 SD Parameter). 431 5. Payload and Certificate Blocks 433 Certificate Blocks and Payload Blocks provide key management in 434 syslog-sign. Their purpose is to support key management using public 435 key cryptosystems. 437 5.1. Preliminaries: Key Management and Distribution Issues 439 A Payload Block contains public key certificate information that is 440 to be conveyed to the receiver. A Payload Block is not sent 441 directly, but in (one or more) fragments. Those fragments are termed 442 Certificate Blocks. All devices send at least one Certificate Block 443 at the beginning of a new reboot session, carrying public key 444 information that is to be in effect for the reboot session. 446 There are three key points to understand about Certificate Blocks: 448 a. They handle a variable-sized payload, fragmenting it if necessary 449 and transmitting the fragments as legal syslog messages. This 450 payload is built (as described below) at the beginning of a 451 reboot session and is transmitted in pieces with each Certificate 452 Block carrying a piece. Note that there is exactly one Payload 453 Block per reboot session. 455 b. The Certificate Blocks are digitally signed. The device does not 456 sign the Payload Block, but the signatures on the Certificate 457 Blocks ensure its authenticity. Note that it may not even be 458 possible to verify the signature on the Certificate Blocks 459 without the information in the Payload Block; in this case the 460 Payload Block is reconstructed, the key is extracted, and then 461 the Certificate Blocks are verified. (This is necessary even 462 when the Payload Block carries a certificate, since some other 463 fields of the Payload Block aren't otherwise verified.) In 464 practice, most installations keep the same public key over long 465 periods of time, so that most of the time, it's easy to verify 466 the signatures on the Certificate Blocks, and use the Payload 467 Block to provide other useful per-session information. 469 c. The kind of Payload Block that is expected is determined by what 470 kind of key material is on the collector that receives it. The 471 device and collector (or offline log viewer) has both some key 472 material (such as a root public key, or predistributed public 473 key), and an acceptable value for the Key Blob Type in the 474 Payload Block, below. The collector or offline log viewer MUST 475 NOT accept a Payload Block of the wrong type. 477 5.2. Building the Payload Block 479 The Payload Block is built when a new reboot session is started. 480 There is a one-to-one correspondence of reboot sessions to Payload 481 Blocks. That is, each reboot session has only one Payload Block, 482 regardless of how many signature groups it may support. A Payload 483 Block MUST have the following fields. Each of these fields are 484 separated by a single space character. (Note that because a Payload 485 Block is not carried in a syslog message directly, only the 486 corresponding Certificate Blocks, it does not need to be encoded as 487 an SD ELEMENT.) 489 a. Unique identifier of sender; by default, the sender's IP address 490 in dotted-decimal (IPv4) or colon-separated (IPv6) notation. 492 b. Full local time stamp for the device at the time the reboot 493 session started. This must be in TIMESTAMP-3339 format. 495 c. Key Blob Type, a one-byte field which holds one of five values: 497 1. 'C' -- a PKIX certificate. 499 2. 'P' -- an OpenPGP certificate. 501 3. 'K' -- the public key whose corresponding private key is 502 being used to sign these messages. 504 4. 'N' -- no key information sent; key is predistributed. 506 5. 'U' -- installation-specific key exchange information 508 d. The key blob, consisting of the raw key data, if any, base 64 509 encoded. 511 5.3. Building the Certificate Block 513 The Certificate Block must get the Payload Block to the collector. 514 Since certificates can legitimately be much longer than 1024 bytes, 515 each Certificate Block carries a piece of the Payload Block. Note 516 that the device MAY make the Certificate Blocks of any legal length 517 (that is, any length less than 1024 bytes) which holds all the 518 required fields. Software that processes Certificate Blocks MUST 519 deal correctly with blocks of any legal length. 521 Like a Signature Block, the Certificate Block is encoded as an SD 522 Element per RFC xxxx [24] and carried in its own syslog message. The 523 SD-ID of the Certificate Block is "ssign-cert". The Certificate 524 Block is composed of the following fields, each of which is encoded 525 as an SD Parameter with parameter name as indicated. Each field must 526 be printable ASCII, and any binary values are base 64 encoded. 528 Field SD-PARAM-NAME Size in bytes 529 ----- ------------- ---- -- ----- 531 Version VER 4 533 Reboot Session ID RSID 1-10 535 Signature Group SG 1 537 Signature Priority SPRI 1-3 539 Total Payload Block Length TPBL 1-8 541 Index into Payload Block INDEX 1-8 543 Fragment Length FLEN 1-3 545 Payload Block Fragment FRAG variable 546 (base 64 encoded binary) 548 Signature SIGN variable 549 (base 64 encoded binary) 551 A Certificate Block is accordingly encoded as follows (xxx denoting a 552 placeholder for the particular value: 554 "[ssign-cert VER=xxx RSID=xxx SG=xxx SPRI=xxx TBPL=xxx INDEX=xxx 555 FLEN=xxx FRAG=xxx SIGN=xxx]". 557 The fields will be explained below. 559 5.3.1. Version 561 The signature group version field is 4 characters in length and is 562 terminated with a space character. This field is identical in nature 563 to the Version field described in Section 4.2. As such, the version, 564 hash algorithm and signature scheme defined in this document may be 565 represented as "0111" (without the quote marks). 567 5.3.2. Reboot Session ID 569 The Reboot Session ID is identical in characteristics to the RSID 570 field described in Section 4.3. 572 5.3.3. Signature Group and Signature Priority 574 The SIG field is identical in characteristics to the SIG field 575 described in Section 4.9. Also, the SPRI field is identical to the 576 SPRI field described there. 578 5.3.4. Total Payload Block Length 580 The Total Payload Block Length is a value representing the total 581 length of the Payload Block in bytes in decimal. This will be one to 582 eight bytes. 584 5.3.5. Index into Payload Block 586 This is a value between 1 and 8 bytes. It contains the number of 587 bytes into the Payload Block where this fragment starts. The first 588 byte of the first fragment is numbered "1". 590 5.3.6. Fragment Length 592 The total length of this fragment expressed as a decimal integer. 593 This will be one to three bytes. 595 5.3.7. Signature 597 This is a digital signature, encoded in base 64, as per RFC 2045. 598 The signature is calculated over all fields but excludes the space 599 characters between them. The Version field effectively specifies the 600 original encoding of the signature. The signature is a signature 601 over the entire data, including all of the PRI, HEADER, and hashes in 602 the hash block. This is consistent with the method of calculating 603 the signature as specified in Section 4.9. To reiterate, the 604 signature is calculated over the completely formatted syslog-message, 605 excluding spaces between fields, and also excluding this signature 606 field. 608 6. Redundancy and Flexibility 610 There is a general rule that determines how redundancy works and what 611 level of flexibility the device and collector have in message 612 formats: in general, the device is allowed to send Signature and 613 Certificate Blocks multiple times, to send Signature and Certificate 614 Blocks of any legal length, to include fewer hashes in hash blocks, 615 etc. 617 6.1. Redundancy 619 Syslog messages are sent over unreliable transport, which means that 620 they can be lost in transit. However, the collector must receive 621 Signature and Certificate Blocks or many messages may not be able to 622 be verified. Sending Signature and Certificate Blocks multiple times 623 provides redundancy; since the collector MUST ignore Signature/ 624 Certificate Blocks it has already received and authenticated, the 625 device can in principle change its redundancy level for any reason, 626 without communicating this fact to the collector. 628 Although the device isn't constrained in how it decides to send 629 redundant Signature and Certificate Blocks, or even in whether it 630 decides to send along multiple copies of normal syslog messages, here 631 we define some redundancy parameters below which may be useful in 632 controlling redundant transmission from the device to the collector. 634 6.1.1. Certificate Blocks 636 certInitialRepeat = number of times each Certificate Block should be 637 sent before the first message is sent. 639 certResendDelay = maximum time delay in seconds to delay before next 640 redundant sending. 642 certResendCount = maximum number of sent messages to delay before 643 next redundant sending. 645 6.1.2. Signature Blocks 647 sigNumberResends = number of times a Signature Block is resent. 649 sigResendDelay = maximum time delay in seconds from original sending 650 to next redundant sending. 652 sigResendCount = maximum number of sent messages to delay before next 653 redundant sending. 655 6.2. Flexibility 657 The device may change many things about the makeup of Signature and 658 Certificate Blocks in a given reboot session. The things it cannot 659 change are: 661 * The version 663 * The number or arrangements of signature groups 665 It is legitimate for a device to send out short Signature Blocks, in 666 order to keep the collector able to verify messages quickly. In 667 general, unless something verified by the Payload Block or 668 Certificate Blocks is changed within the reboot session ID, any 669 change is allowed to the Signature or Certificate Blocks during the 670 session. 672 7. Efficient Verification of Logs 674 The logs secured with syslog-sign may either be reviewed online or 675 offline. Online review is somewhat more complicated and 676 computationally expensive, but not prohibitively so. 678 7.1. Offline Review of Logs 680 When the collector stores logs and reviewed later, they can be 681 authenticated offline just before they are reviewed. Reviewing these 682 logs offline is simple and relatively cheap in terms of resources 683 used, so long as there is enough space available on the reviewing 684 machine. Here, we consider that the stored log files have already 685 been separated by sender, reboot session ID, and signature group. 686 This can be done very easily with a script file. We then do the 687 following: 689 a. First, we go through the raw log file, and split its contents 690 into three files. Each message in the raw log file is classified 691 as a normal message, a Signature Block, or a Certificate Block. 692 Certificate Blocks and Signature Blocks are stored in their own 693 files. Normal messages are stored in a keyed file, indexed on 694 their hash values. 696 b. We sort the Certificate Block file by index value, and check to 697 see if we have a set of Certificate Blocks that can reconstruct 698 the Payload Block. If so, we reconstruct the Payload Block, 699 verify any key-identifying information, and then use this to 700 verify the signatures on the Certificate Blocks we've received. 701 When this is done, we have verified the reboot session and key 702 used for the rest of the process. 704 c. We sort the Signature Block file by firstMessageNumber. We now 705 create an authenticated log file, which consists of some header 706 information, and then a sequence of message number, message text 707 pairs. We next go through the Signature Block file. For each 708 Signature Block in the file, we do the following: 710 1. Verify the signature on the Block. 712 2. For each hashed message in the Block: 714 a. Look up the hash value in the keyed message file. 716 b. If the message is found, write (message number, message 717 text) to the authenticated log file. 719 3. Skip all other Signature Blocks with the same 720 firstMessageNumber. 722 d. The resulting authenticated log file contains all messages that 723 have been authenticated, and implicitly indicates (by missing 724 message numbers) all gaps in the authenticated messages. 726 It's pretty easy to see that, assuming sufficient space for building 727 the keyed file, this whole process is linear in the number of 728 messages (generally two seeks, one to write and the other to read, 729 per normal message received), and O(N lg N) in the number of 730 Signature Blocks. This estimate comes with two caveats: first, the 731 Signature Blocks arrive very nearly in sorted order, and so can 732 probably be sorted more cheaply on average than O(N lg N) steps. 733 Second, the signature verification on each Signature Block almost 734 certainly is more expensive than the sorting step in practice. We 735 haven't discussed error-recovery, which may be necessary for the 736 Certificate Blocks. In practice, a very simple error-recovery 737 strategy is probably good enough -- if the Payload Block doesn't come 738 out as valid, then we can just try an alternate instance of each 739 Certificate Block, if such are available, until we get the Payload 740 Block right. 742 It's easy for an attacker to flood us with plausible-looking 743 messages, Signature Blocks, and Certificate Blocks. 745 7.2. Online Review of Logs 747 Some processes on the collector machine may need to monitor log 748 messages in something very close to real-time. This can be done with 749 syslog-sign, though it is somewhat more complex than the offline 750 analysis. This is done as follows: 752 a. We have an output queue, into which we write (message number, 753 message text) pairs which have been authenticated. Again, we'll 754 assume we're handling only one signature group, and only one 755 reboot session ID, at any given time. 757 b. We have three data structures: A queue into which (message 758 number, hash of message) pairs is kept in sorted order, a queue 759 into which (arrival sequence, hash of message) is kept in sorted 760 order, and a hash table which stores (message text, count) 761 indexed by hash value. In this file, count may be any number 762 greater than zero; when count is zero, the entry in the hash 763 table is cleared. 765 c. We must receive all the Certificate Blocks before any other 766 processing can really be done. (This is why they're sent first.) 767 Once that's done, any Certificate Block that arrives is 768 discarded. 770 d. Whenever a normal message arrives, we add (arrival sequence, hash 771 of message) to our message queue. If our hash table has an entry 772 for the message's hash value, we increment its count by one; 773 otherwise, we create a new entry with count = 1. When the 774 message queue is full, we roll the oldest messages off the queue 775 by taking the last entry in the queue, and using it to index the 776 hash table. If that entry has count is 1, we delete the entry in 777 the hash table; otherwise, we decrement its count. We then 778 delete the last entry in the queue. 780 e. Whenever a Signature Block arrives, we first check to see if the 781 firstMessageNumber value is too old, or if another Signature 782 Block with that firstMessageNumber has already been received. If 783 so, we discard the Signature Block unread. Otherwise, we check 784 its signature, and discard it if the signature isn't valid. A 785 Signature Block contains a sequence of (message number, message 786 hash) pairs. For each pair, we first check to see if the message 787 hash is in the hash table. If so, we write out the (message 788 number, message text) in the authenticated message queue. 789 Otherwise, we write the (message number, message hash) to the 790 message number queue. This generally involves rolling the oldest 791 entry out of this queue: before this is done, that entry's hash 792 value is again searched for in the hash table. If a matching 793 entry is found, the (message number, message text) pair is 794 written out to the authenticated message queue. In either case, 795 the oldest entry is then discarded. 797 f. The result of this is a sequence of messages in the authenticated 798 message queue, each of which has been authenticated, and which 799 are combined with numbers showing their order of original 800 transmission. 802 It's not too hard to see that this whole process is roughly linear in 803 the number of messages, and also in the number of Signature Blocks 804 received. The process is susceptible to flooding attacks; an 805 attacker can send enough normal messages that the messages roll off 806 their queue before their Signature Blocks can be processed. 808 8. Security Considerations 810 Normal syslog event messages are unsigned and have most of the 811 security attributes described in Section 6 of RFC 3164. This 812 document also describes Certificate Blocks and Signature Blocks which 813 are signed syslog messages. The Signature Blocks contains signature 814 information of previously sent syslog event messages. All of this 815 information may be used to authenticate syslog messages and to 816 minimize or obviate many of the security concerns described in RFC 817 3164. 819 8.1. Cryptography Constraints 821 As with any technology involving cryptography, you should check the 822 current literature to determine if any algorithms used here have been 823 found to be vulnerable to attack. 825 This specification uses Public Key Cryptography technologies. The 826 proper party or parties must control the private key portion of a 827 public-private key pair. Any party that controls a private key may 828 sign anything they please. 830 Certain operations in this specification involve the use of random 831 numbers. An appropriate entropy source should be used to generate 832 these numbers. See RFC 1750 [8]. 834 8.2. Packet Parameters 836 The message length must not exceed 1024 bytes. Various problems may 837 result if a device sends out messages with a length greater than 1024 838 bytes. As seen in RFC 3164, relays MAY truncate messages with 839 lengths greater than 1024 bytes which would result in a problem for 840 receivers trying to validate a hash of the packet. In this case, as 841 with all others, it is best to be conservative with what you send but 842 liberal in what you receive, and accept more than 1024 bytes. 844 Similarly, senders must rigidly enforce the correctness of the 845 message body. This document specifies an enhancement to the syslog 846 protocol but does not stipulate any specific syslog message format. 847 Nonetheless, problems may arise if the receiver does not fully accept 848 the syslog packets sent from a device, or if it has problems with the 849 format of the Certificate Block or Signature Block messages. 851 Finally, receivers must not malfunction if they receive syslog 852 messages containing characters other than those specified in this 853 document. 855 8.3. Message Authenticity 857 Event messages being sent through syslog do not strongly associate 858 the message with the message sender. That fact is established by the 859 receiver upon verification of the Signature Block as described above. 860 Before a Signature Block is used to ascertain the authenticity of an 861 event message, it may be received, stored and reviewed by a person or 862 automated parser. Both of these should maintain doubt about the 863 authenticity of the message until after it has been validated by 864 checking the contents of the Signature Block. 866 With the Signature Block checking, an attacker may only forge 867 messages if they can compromise the private key of the true sender. 869 8.4. Sequenced Delivery 871 Event messages may be recorded and replayed by an attacker. However 872 the information contained in the Signature Blocks allows a reviewer 873 to determine if the received messages are the ones originally sent by 874 a device. This process also alerts the reviewer to replayed 875 messages. 877 8.5. Replaying 879 Event messages may be recorded and replayed by an attacker. However 880 the information contained in the Signature Blocks will allow a 881 reviewer to determine if the received messages are the ones 882 originally sent by a device. This process will also alert the 883 reviewer to replayed messages. 885 8.6. Reliable Delivery 887 RFC 3195 may be used for the reliable delivery of all syslog 888 messages. This document acknowledges that event messages sent over 889 UDP may be lost in transit. A proper review of the Signature Block 890 information may pinpoint any messages sent by the sender but not 891 received by the receiver. The overlap of information in subsequent 892 Signature Block information allows a reviewer to determine if any 893 Signature Block messages were also lost in transit. 895 8.7. Sequenced Delivery 897 Related to the above, syslog messages delivered over UDP not only may 898 be lost, but they may arrive out of sequence. The information 899 contained in the Signature Block allows a receiver to correctly order 900 the event messages. Beyond that, the timestamp information contained 901 in the packet may help the reviewer to visually order received 902 messages even if they are received out of order. 904 8.8. Message Integrity 906 syslog messages may be damaged in transit. A review of the 907 information in the Signature Block determines if the received message 908 was the intended message sent by the sender. A damaged Signature 909 Block or Certificate Block will be evident since the receiver will 910 not be able to validate that it was signed by the sender. 912 8.9. Message Observation 914 Event messages, Certificate Blocks and Signature Blocks are all sent 915 in plaintext. Generally this has had the benefit of allowing network 916 administrators to read the message when sniffing the wire. However, 917 this also allows an attacker to see the contents of event messages 918 and perhaps to use that information for malicious purposes. 920 8.10. Man In The Middle 922 It is conceivable that an attacker may intercept Certificate Blocks 923 and insert their own Certificate information. In that case, the 924 attacker would be able to receive event messages from the actual 925 sender and then relay modified messages, insert new messages, or 926 deleted messages. They would then be able to construct a Signature 927 Block and sign it with their own private key. The network 928 administrators should verify that the key contained in the 929 Certificate Block is indeed the key being used on the actual device. 930 If that is indeed the case, then this MITM attack will not succeed. 932 8.11. Denial of Service 934 An attacker may be able to overwhelm a receiver by sending it invalid 935 Signature Block messages. If the receiver is attempting to process 936 these messages online, it may consume all available resources. For 937 this reason, it may be appropriate to just receive the Signature 938 Block messages and process them as time permits. 940 As with any system, an attacker may also just overwhelm a receiver by 941 sending more messages to it than can be handled by the infrastructure 942 or the device itself. Implementors should attempt to provide 943 features that minimize this threat. Such as only receiving syslog 944 messages from known IP addresses. 946 8.12. Covert Channels 948 Nothing in this protocol attempts to eliminate covert channels. 949 Indeed, the unformatted message syntax in the packets could be very 950 amenable to sending embedded secret messages. In fact, just about 951 every aspect of syslog messages lends itself to the conveyance of 952 covert signals. For example, a collusionist could send odd and even 953 PRI values to indicate Morse Code dashes and dots. 955 9. IANA Considerations 957 Two syslog packet types are specified in this document; the Signature 958 Block and the Certificate Block. Each of these has several fields 959 specified that should be controlled by the IANA. Essentially these 960 packet types may be differentiated based upon the value in the Cookie 961 field. The Signature Block packet may be identified by a value of 962 "@#sigSIG" in the Cookie field. The Certificate Block packet may be 963 identified by a value of "@#sigCER" in the Cookie field. Each of 964 these packet types share fields that should be consistent; 965 specifically, the Certificate Block packet types may be considered to 966 be an announcement of capabilities and the Signature Block packets 967 SHOULD have the same values in the fields described in this section. 968 This document allows that there may be some really fine reason for 969 the values to be different between the two packet types but the 970 authors and contributors can't see any valid reason for that at this 971 time. 973 This document also upholds the Facilities and Severities listed in 974 RFC 3164 [20]. Those values range from 0 to 191. This document also 975 instructs the IANA to reserve all other possible values of the 976 Severities and Facilities above the value of 191 and to distribute 977 them via the consensus process as defined in RFC 2434 [17]. 979 The following fields are to be controlled by the IANA in both the 980 Signature Block packets and the Certificate Block packets. 982 9.1. Version Field 984 The Version field (Ver) is a 4 byte field. The first two bytes of 985 this field define the version of the Signature Block packets and the 986 Certificate Block Packets. This allows for future efforts to 987 redefine the subsequent fields in the Signature Block packets and 988 Certificate Block packets. A value of "00" is reserved and not used. 989 This document describes the fields for the version value of "01". It 990 is expected that this value be incremented monotonically with decimal 991 values up through "50" for IANA assigned values. Values "02" through 992 "50" will be assigned by the IANA using the "IETF Consensus" policy 993 defined in RFC 2434 [17]. It is not anticipated that these values 994 will be reused. Values of "51" through "99" will be vendor-specific, 995 and values in this range are not to be assigned by the IANA. 997 In the case of vendor-specific assigned Version numbers, all 998 subsequent values defined in the packet will then have vendor- 999 specific meaning. They may, or may not, align with the values 1000 assigned by the IANA for these fields. For example, a vendor may 1001 choose to define their own Version of "51" still containing values of 1002 "1" for the Hash Algorithm and Signature Scheme which aligns with the 1003 IANA assigned values as defined in this document. However, they may 1004 then choose to define a value of "5" for the Signature Group for 1005 their own reasons. 1007 The third byte of the Ver field defines the Hash Algorithm. It is 1008 envisioned that this will also be a monotonically increasing value 1009 with a maximum value of "9". The value of "1" is defined in this 1010 document as the first assigned value and is SHA1 FIPS-180-1.1995 [2]. 1011 Subsequent values will be assigned by the IANA using the "IETF 1012 Consensus" policy defined in RFC 2434 [17]. 1014 The forth and final byte of the Ver field defines the Signature 1015 Scheme. It is envisioned that this too will be a monotonically 1016 increasing value with a maximum value of "9". The value of "1" is 1017 defined in this document as OpenPGP DSA - RFC 2440 [18], FIPS.186- 1018 1.1998 [1]. Subsequent values will be assigned by the IANA using the 1019 "IETF Consensus" policy defined in RFC 2434 [17]. The fields, values 1020 assigned in this document and ranges are illustrated in the following 1021 table. 1023 Field Value Defined IANA Assigned Vendor Specific 1024 in this Document Range Range 1025 ----- ---------------- ------------- --------------- 1026 Ver 1027 ver 01 01-50 50-99 1028 hash 1 0-9 -none- 1029 sig 1 0-9 -none- 1031 If either the Hash Algorithm field or the Signature Scheme field is 1032 needed to go beyond "9" within the current version (first two bytes), 1033 the IANA should increment the first two bytes of this 4 byte field to 1034 be the next value with the definition that all of the subsequent 1035 values of fields described in this section are reset to "0" while 1036 retaining the latest definitions given by the IANA. For example, 1037 consider the case that the first two characters are "23" and the 1038 latest Signature Algorithm is 4. Let's say that the latest Hash 1039 Algorithm value is "9" but a better Hash Algorithm is defined. In 1040 that case, the IANA will increment the first two bytes to become 1041 "24", retain the current Hash Algorithm to be "0", define the new 1042 Hash Algorithm to be "1" in this scheme, and define the current 1043 Signature Scheme to also be "0". This example is illustrated in the 1044 following table. 1046 Current New - Equivalent New with Later 1047 to "Current" Algorithms 1048 ------- -------------- --------------- 1049 ver = 23 ver = 24 ver = 24 1050 hash = 9 hash = 0 hash = 1 1051 sig = 4 sig = 0 sig = 0 1053 9.2. SIG Field 1055 The SIG field values are numbers as defined in Section 4.4. Values 1056 "0" through "3" are assigned in this document. The IANA shall assign 1057 values "4" through "7" using the "IETF Consensus" policy defined in 1058 RFC 2434 [17]. Values "8" and "9" shall be left as vendor specific 1059 and shall not be assigned by the IANA. 1061 9.3. Key Blob Type 1063 Section Section 5.2 defines five, one character identifiers for the 1064 key blob type. These are the uppercase letters, "C", "P", "K", "N", 1065 and "U". All other uppercase letters shall be assigned by the IANA 1066 using the "IETF Consensus" policy defined in RFC 2434 [17]. 1067 Lowercase letters are left as vendor specific and shall not be 1068 assigned by the IANA. 1070 10. Authors and Working Group Chair 1072 The working group can be contacted via the mailing list: 1074 syslog-sec@employees.org 1076 The current Chair of the Working Group may be contacted at: 1078 Chris Lonvick 1079 Cisco Systems 1080 Email: clonvick@cisco.com 1082 The authors of this draft are: 1084 John Kelsey 1085 Email: kelsey.j@ix.netcom.com 1087 Jon Callas 1088 Email: jon@callas.org 1090 Alexander Clemm 1091 Email: alex@cisco.com 1093 11. Acknowledgements 1095 The authors wish to thank Alex Brown, Chris Calabrese, Carson Gaspar, 1096 Drew Gross, Chris Lonvick, Darrin New, Marshall Rose, Holt Sorenson, 1097 Rodney Thayer, Andrew Ross, Rainer Gerhards, Albert Mietus, and the 1098 many Counterpane Internet Security engineering and operations people 1099 who commented on various versions of this proposal. 1101 12. References 1103 [1] National Institute of Standards and Technology, "Digital 1104 Signature Standard", FIPS PUB 186-1, December 1998, 1105 . 1107 [2] National Institute of Standards and Technology, "Secure Hash 1108 Standard", FIPS PUB 180-1, April 1995, 1109 . 1111 [3] American National Standards Institute, "USA Code for 1112 Information Interchange", ANSI X3.4, 1968. 1114 [4] Menezes, A., van Oorschot, P., and S. Vanstone, ""Handbook of 1115 Applied Cryptography", CRC Press", 1996. 1117 [5] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1118 August 1980. 1120 [6] Mockapetris, P., "Domain names - concepts and facilities", 1121 STD 13, RFC 1034, November 1987. 1123 [7] Mockapetris, P., "Domain names - implementation and 1124 specification", STD 13, RFC 1035, November 1987. 1126 [8] Eastlake, D., Crocker, S., and J. Schiller, "Randomness 1127 Recommendations for Security", RFC 1750, December 1994. 1129 [9] Malkin, G., "Internet Users' Glossary", RFC 1983, August 1996. 1131 [10] Freed, N. and N. Borenstein, "Multipurpose Internet Mail 1132 Extensions (MIME) Part One: Format of Internet Message Bodies", 1133 RFC 2045, November 1996. 1135 [11] Oehler, M. and R. Glenn, "HMAC-MD5 IP Authentication with 1136 Replay Prevention", RFC 2085, February 1997. 1138 [12] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-Hashing 1139 for Message Authentication", RFC 2104, February 1997. 1141 [13] Bradner, S., "Key words for use in RFCs to Indicate Requirement 1142 Levels", BCP 14, RFC 2119, March 1997. 1144 [14] Yergeau, F., "UTF-8, a transformation format of ISO 10646", 1145 RFC 2279, January 1998. 1147 [15] Crocker, D. and P. Overell, "Augmented BNF for Syntax 1148 Specifications: ABNF", RFC 2234, November 1997. 1150 [16] Hinden, R. and S. Deering, "IP Version 6 Addressing 1151 Architecture", RFC 2373, July 1998. 1153 [17] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA 1154 Considerations Section in RFCs", BCP 26, RFC 2434, 1155 October 1998. 1157 [18] Callas, J., Donnerhacke, L., Finney, H., and R. Thayer, 1158 "OpenPGP Message Format", RFC 2440, November 1998. 1160 [19] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) 1161 for version 3 of the Simple Network Management Protocol 1162 (SNMPv3)", RFC 2574, April 1999. 1164 [20] Lonvick, C., "The BSD Syslog Protocol", RFC 3164, August 2001. 1166 [21] New, D. and M. Rose, "Reliable Delivery for syslog", RFC 3195, 1167 November 2001. 1169 [22] Klyne, G. and C. Newman, "Date and Time on the Internet: 1170 Timestamps", RFC 3339, July 2002. 1172 [23] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", 1173 RFC 3548, July 2003. 1175 [24] Gerhards, R., "The syslog Protocol, 1176 draft-ietf-syslog-protocol-16.txt (work in progress)", 1177 January 2006. 1179 [25] Schneier, B., "Applied Cryptography Second Edition: protocols, 1180 algorithms, and source code in C", 1996. 1182 Authors' Addresses 1184 John Kelsey 1186 Email: kelsey.j@ix.netcom.com 1188 Jon Callas 1189 PGP Corporation 1191 Email: jon@callas.org 1193 Alexander Clemm 1194 Cisco Systems 1196 Email: alex@cisco.com 1198 Intellectual Property Statement 1200 The IETF takes no position regarding the validity or scope of any 1201 Intellectual Property Rights or other rights that might be claimed to 1202 pertain to the implementation or use of the technology described in 1203 this document or the extent to which any license under such rights 1204 might or might not be available; nor does it represent that it has 1205 made any independent effort to identify any such rights. Information 1206 on the procedures with respect to rights in RFC documents can be 1207 found in BCP 78 and BCP 79. 1209 Copies of IPR disclosures made to the IETF Secretariat and any 1210 assurances of licenses to be made available, or the result of an 1211 attempt made to obtain a general license or permission for the use of 1212 such proprietary rights by implementers or users of this 1213 specification can be obtained from the IETF on-line IPR repository at 1214 http://www.ietf.org/ipr. 1216 The IETF invites any interested party to bring to its attention any 1217 copyrights, patents or patent applications, or other proprietary 1218 rights that may cover technology that may be required to implement 1219 this standard. Please address the information to the IETF at 1220 ietf-ipr@ietf.org. 1222 Disclaimer of Validity 1224 This document and the information contained herein are provided on an 1225 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 1226 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 1227 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 1228 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 1229 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 1230 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1232 Copyright Statement 1234 Copyright (C) The Internet Society (2006). This document is subject 1235 to the rights, licenses and restrictions contained in BCP 78, and 1236 except as set forth therein, the authors retain all their rights. 1238 Acknowledgment 1240 Funding for the RFC Editor function is currently provided by the 1241 Internet Society.