1 2NETWORK WORKING GROUP L. Zhu 3Internet-Draft K. Jaganathan 4Expires: February 8, 2005 Microsoft Corporation 5 N. Williams 6 Sun Microsystems 7 August 10, 2004 8 9 10 11 OCSP Support for PKINIT 12 draft-ietf-krb-wg-ocsp-for-pkinit-01 13 14 15Status of this Memo 16 17 18 This document is an Internet-Draft and is subject to all provisions 19 of section 3 of RFC 3667. By submitting this Internet-Draft, each 20 author represents that any applicable patent or other IPR claims of 21 which he or she is aware have been or will be disclosed, and any of 22 which he or she become aware will be disclosed, in accordance with 23 RFC 3668. 24 25 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF), its areas, and its working groups. Note that 28 other groups may also distribute working documents as 29 Internet-Drafts. 30 31 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 36 37 38 The list of current Internet-Drafts can be accessed at 39 http://www.ietf.org/ietf/1id-abstracts.txt. 40 41 42 The list of Internet-Draft Shadow Directories can be accessed at 43 http://www.ietf.org/shadow.html. 44 45 46 This Internet-Draft will expire on February 8, 2005. 47 48 49Copyright Notice 50 51 52 Copyright (C) The Internet Society (2004). 53 54 55Abstract 56 57 58 This document defines a mechanism to enable in-band transmission of 59 OCSP responses. These responses are used to verify the validity of 60 the certificates used in PKINIT - the Kerberos Version 5 extension 61 that provides for the use of public key cryptography. 62 63 64 65 66 67Zhu, et al. Expires February 8, 2005 [Page 1] 68Internet-Draft OCSP Support for PKINIT August 2004 69 70 71 72Table of Contents 73 74 75 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 76 2. Conventions Used in This Document . . . . . . . . . . . . . . 4 77 3. Message Definition . . . . . . . . . . . . . . . . . . . . . . 5 78 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 79 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 80 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 7 82 Intellectual Property and Copyright Statements . . . . . . . . 9 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125Zhu, et al. Expires February 8, 2005 [Page 2] 126Internet-Draft OCSP Support for PKINIT August 2004 127 128 129 1301. Introduction 131 132 133 Online Certificate Status Protocol (OCSP) [RFC2560] enables 134 applications to obtain timely information regarding the revocation 135 status of a certificate. Because OCSP responses are well-bounded and 136 small in size, constrained clients may wish to use OCSP to check the 137 validity of KDC certificates in order to avoid transmission of large 138 Certificate Revocation Lists (CRLs) and therefore save bandwidth on 139 constrained networks. 140 141 142 This document defines a pre-authentication type [CLARIFICATIONS], 143 where the client and the KDC MAY piggyback OCSP responses for 144 certificates used in authentication exchanges, as defined in 145 [PKINIT]. 146 147 148 By using this OPTIONAL extension, PKINIT clients and the KDC can 149 maximize the reuse of cached OCSP responses. 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185Zhu, et al. Expires February 8, 2005 [Page 3] 186Internet-Draft OCSP Support for PKINIT August 2004 187 188 189 1902. Conventions Used in This Document 191 192 193 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 194 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 195 document are to be interpreted as described in [RFC2119]. 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243Zhu, et al. Expires February 8, 2005 [Page 4] 244Internet-Draft OCSP Support for PKINIT August 2004 245 246 247 2483. Message Definition 249 250 251 A pre-authentication type identifier is defined for this mechanism: 252 253 254 PA-PK-OCSP-RESPONSE 16 255 256 257 The corresponding pre-authentication field contains OCSP data as 258 follows: 259 260 261 PA-PK-OCSP-DATA ::= SEQUENCE OF OcspResponse 262 263 264 OcspResponse ::= OCTET STRING 265 -- contains a complete OCSP response, 266 -- defined in [RFC2560] 267 268 269 The client MAY send OCSP responses for certificates used in 270 PA-PK-AS-REQ [PKINIT] via a PA-PK-OCSP-RESPONSE. 271 272 273 The KDC that receives a PA-PK-OCSP-RESPONSE the SHOULD send a 274 PA-PK-OCSP-RESPONSE in response. The client can request a 275 PA-PK-OCSP-RESPONSE by using an empty sequence in its request. 276 277 278 The KDC MAY send a PA-PK-OCSP-RESPONSE when it does not receive a 279 PA-PK-OCSP-RESPONSE from the client. 280 281 282 The PA-PK-OCSP-RESPONSE sent by the KDC contains OCSP responses for 283 certificates used in PA-PK-AS-REP [PKINIT]. 284 285 286 Note the lack of integrity protection for the empty or missing OCSP 287 response; lack of an expected OCSP response from the KDC for the 288 KDC's certificates SHOULD be treated as an error by the client, 289 unless it is configured otherwise. 290 291 292 When using OCSP, the response is signed by the OCSP server, which is 293 trusted by the receiver. Depending on local policy, further 294 verification of the validity of the OCSP servers MAY need to be done. 295 296 297 The client and the KDC SHOULD ignore invalid OCSP responses received 298 via this mechanism, and they MAY implement CRL processing logic as a 299 fall-back position, if the OCSP responses received via this mechanism 300 alone are not sufficient for the verification of certificate 301 validity. The client and/or the KDC MAY ignore a valid OCSP response 302 and perform their own revocation status verification independently. 303 304 305 306 307 308 309 310 311 312Zhu, et al. Expires February 8, 2005 [Page 5] 313Internet-Draft OCSP Support for PKINIT August 2004 314 315 316 3174. Security Considerations 318 319 320 The pre-authentication data in this document do not actually 321 authenticate any principals, and MUST be used in conjunction with 322 PKINIT. 323 324 325 There is a downgrade attack against clients which want OCSP responses 326 from the KDC for the KDC's certificates. The clients, however, can 327 treat the absence of valid OCSP responses as an error, based on their 328 local configuration. 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371Zhu, et al. Expires February 8, 2005 [Page 6] 372Internet-Draft OCSP Support for PKINIT August 2004 373 374 375 3765. IANA Considerations 377 378 379 This document defines a new pre-authentication type for use with 380 PKINIT to encode OCSP responses. The official value for this padata 381 identifier need to be acquired from IANA. 382 383 3846 References 385 386 387 [CLARIFICATIONS] 388 Neuman, B., Yu, Y., Hartman, S. and K. Raeburn, "The 389 Kerberos Network Authentication Service (V5)", 390 draft-ietf-krb-wg-kerberos-clarifications, Work in 391 progress. 392 393 394 [PKINIT] Tung, B. and B. Neuman, "Public Key Cryptography for 395 Initial Authentication in Kerberos", 396 draft-ietf-cat-kerberos-pk-init, Work in progress. 397 398 399 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 400 Requirement Levels", BCP 14, RFC 2119, March 1997. 401 402 403 [RFC2560] Myers, M., Ankney, R., Malpani, A., Galperin, S. and C. 404 Adams, "X.509 Internet Public Key Infrastructure Online 405 Certificate Status Protocol - OCSP", RFC 2560, June 1999. 406 407 408 409Authors' Addresses 410 411 412 Larry Zhu 413 Microsoft Corporation 414 One Microsoft Way 415 Redmond, WA 98052 416 US 417 418 419 EMail: lzhu@microsoft.com 420 421 422 423 Karthik Jaganathan 424 Microsoft Corporation 425 One Microsoft Way 426 Redmond, WA 98052 427 US 428 429 430 EMail: karthikj@microsoft.com 431 432 433 434 435 436 437 438 439 440 441Zhu, et al. Expires February 8, 2005 [Page 7] 442Internet-Draft OCSP Support for PKINIT August 2004 443 444 445 446 Nicolas Williams 447 Sun Microsystems 448 5300 Riata Trace Ct 449 Austin, TX 78727 450 US 451 452 453 EMail: Nicolas.Williams@sun.com 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499Zhu, et al. Expires February 8, 2005 [Page 8] 500Internet-Draft OCSP Support for PKINIT August 2004 501 502 503 504Intellectual Property Statement 505 506 507 The IETF takes no position regarding the validity or scope of any 508 Intellectual Property Rights or other rights that might be claimed to 509 pertain to the implementation or use of the technology described in 510 this document or the extent to which any license under such rights 511 might or might not be available; nor does it represent that it has 512 made any independent effort to identify any such rights. Information 513 on the procedures with respect to rights in RFC documents can be 514 found in BCP 78 and BCP 79. 515 516 517 Copies of IPR disclosures made to the IETF Secretariat and any 518 assurances of licenses to be made available, or the result of an 519 attempt made to obtain a general license or permission for the use of 520 such proprietary rights by implementers or users of this 521 specification can be obtained from the IETF on-line IPR repository at 522 http://www.ietf.org/ipr. 523 524 525 The IETF invites any interested party to bring to its attention any 526 copyrights, patents or patent applications, or other proprietary 527 rights that may cover technology that may be required to implement 528 this standard. Please address the information to the IETF at 529 ietf-ipr@ietf.org. 530 531 532 533Disclaimer of Validity 534 535 536 This document and the information contained herein are provided on an 537 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 538 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 539 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 540 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 541 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 542 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 543 544 545 546Copyright Statement 547 548 549 Copyright (C) The Internet Society (2004). This document is subject 550 to the rights, licenses and restrictions contained in BCP 78, and 551 except as set forth therein, the authors retain all their rights. 552 553 554 555Acknowledgment 556 557 558 This document was based on conversations among the authors, Jeffrey 559 Altman, Sam Hartman, Martin Rex, and other members of the Kerberos 560 working group. 561 562 563 564 565 566Zhu, et al. Expires February 8, 2005 [Page 9]