idnits 2.17.00 (12 Aug 2021) /tmp/idnits47464/draft-ietf-sidr-algorithm-agility-11.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** There is 1 instance of too long lines in the document, the longest one being 23 characters in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors 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 -- however, there's a paragraph with a matching beginning. Boilerplate error? (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (January 15, 2013) is 3412 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) ** Obsolete normative reference: RFC 6485 (Obsoleted by RFC 7935) ** Obsolete normative reference: RFC 6490 (Obsoleted by RFC 7730) Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group R. Gagliano 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track S. Kent 5 Expires: July 19, 2013 BBN Technologies 6 S. Turner 7 IECA, Inc. 8 January 15, 2013 10 Algorithm Agility Procedure for RPKI. 11 draft-ietf-sidr-algorithm-agility-11 13 Abstract 15 This document specifies the process that Certification Authorities 16 (CAs) and Relying Parties (RPs) participating in the Resource Public 17 Key Infrastructure (RPKI) will need to follow to transition to a new 18 (and probably cryptographically stronger) algorithm set. The process 19 is expected to be completed in a time scale of several years. 20 Consequently, no emergency transition is specified. The transition 21 procedure defined in this document supports only a top-down migration 22 (parent migrates before children). 24 Status of this Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on July 19, 2013. 41 Copyright Notice 43 Copyright (c) 2013 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 59 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 61 4. Key Rollover steps for algorithm migration . . . . . . . . . . 8 62 4.1. Milestones definition . . . . . . . . . . . . . . . . . . 8 63 4.2. Process overview . . . . . . . . . . . . . . . . . . . . . 8 64 4.3. Phase 0 . . . . . . . . . . . . . . . . . . . . . . . . . 10 65 4.3.1. Milestone 1 . . . . . . . . . . . . . . . . . . . . . 11 66 4.4. Phase 1 . . . . . . . . . . . . . . . . . . . . . . . . . 12 67 4.5. Phase 2 . . . . . . . . . . . . . . . . . . . . . . . . . 13 68 4.6. Phase 3 . . . . . . . . . . . . . . . . . . . . . . . . . 14 69 4.7. Phase 4 . . . . . . . . . . . . . . . . . . . . . . . . . 15 70 4.8. Return to Phase 0 . . . . . . . . . . . . . . . . . . . . 16 71 5. Multi Algorithm support in the RPKI provisioning protocol . . 17 72 6. Validation of multiple instance of signed products . . . . . . 18 73 7. Revocation . . . . . . . . . . . . . . . . . . . . . . . . . . 19 74 8. Key rollover . . . . . . . . . . . . . . . . . . . . . . . . . 20 75 9. Repository structure . . . . . . . . . . . . . . . . . . . . . 21 76 10. Deprecating an Algorithm Suite . . . . . . . . . . . . . . . . 22 77 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 78 12. Security Considerations . . . . . . . . . . . . . . . . . . . 25 79 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 26 80 14. Normative References . . . . . . . . . . . . . . . . . . . . . 27 81 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 28 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31 84 1. Requirements notation 86 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 87 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "NOT RECOMMENDED" and 88 "OPTIONAL" in this document are to be interpreted as described in 89 [RFC2119]. 91 2. Introduction 93 The RPKI must accommodate transitions between the public keys used by 94 CAs. Transitions of this sort are usually termed "key rollover". 95 Planned key rollover will occur at regular intervals throughout the 96 life of the RPKI, as each CA changes its public keys, in a non- 97 coordinated fashion. (By non-coordinated we mean that the time at 98 which each CA elects to change its keys is locally determined, not 99 coordinated across the RPKI.) Moreover, because a key change might 100 be necessitated by suspected private key compromise, one can never 101 assume coordination of these events among all of the CAs in the RPKI. 102 In an emergency key rollover, the old certificate is revoked and a 103 new certificate with a new key is issued. The mechanisms to perform 104 a key rollover in RPKI (either planned or in an emergency), while 105 maintaining the same algorithm suite, are covered in [RFC6489]. 107 This document describes the mechanism to perform a key rollover in 108 RPKI due to the migration to a new signature algorithm suite. A 109 signature algorithm suite encompasses both a signature algorithm 110 (with a specified key size range) and a one-way hash algorithm. It 111 is anticipated that the RPKI will require the adoption of updated key 112 sizes and/or different algorithm suites over time. This document 113 treats the adoption of a new hash algorithm while retaining the 114 current signature algorithm as equivalent to an algorithm migration, 115 and requires the CA to change its key. Migration to a new algorithm 116 suite will be required in order to maintain an acceptable level of 117 cryptographic security and protect the integrity of certificates, 118 CRLs and signed objects in the RPKI. All of the data structures in 119 the RPKI explicitly identify the signature and hash algorithms being 120 used. However, experience has demonstrated that the ability to 121 represent algorithm IDs is not sufficient to enable migration to new 122 algorithm suites (algorithm agility). One also must ensure that 123 protocols, infrastructure elements, and operational procedures also 124 accommodate the migration from one algorithm suite to another. 125 Algorithm migration is expected to be very infrequent and it will 126 require support of a "current" and "next" suite for a prolonged 127 interval, probably several years. 129 This document defines how entities in the RPKI execute (planned) CA 130 key rollover when the algorithm suite changes. The description 131 covers actions by CAs, repository operators, and RPs. It describes 132 the behavior required of both CAs and RPs to make such key changes 133 work in the RPKI context, including how the RPKI repository system is 134 used to support key rollover. 136 This document does not specify any algorithm suite per se. The RPKI 137 Certificate Policy (CP) [RFC6484] mandates the use of the algorithms 138 defined in [RFC6485] by CAs and RPs. When an algorithm transition is 139 initiated, [RFC6485] MUST be updated (as defined in Section 4.1 of 140 this document) redefining the required algorithm(s) for compliant 141 RPKI CAs and RPs under the CP. The CP will not change as a side 142 effect of algorithm transition (and thus the policy OID in RPKI 143 certificates will not change.) 145 For each algorithm transition, an additional document (the algorithm 146 transition timetable) MUST be published (as an IETF BCP) to define 147 the dates for each milestone defined in this document. It will 148 define dates for the phase transitions, consistent with the 149 descriptions provided in Section 4. It also will describe how the 150 RPKI community will measure the readiness of CAs and RPs to 151 transition to each phase. CAs publish certificates, CRLs, and other 152 signed objects under the new algorithm suite as the transition 153 progresses. This provides visibility into the deployment of the new 154 algorithm suite, enabling the community to evaluate deployment 155 progress. The transition procedure allows CAs to remove old 156 certificates, CRLs, and signed products, after the twilight date. 157 This provides an ability to observe and measure the withdrawal of the 158 old algorithm suite. Thus the phases defined in this document enable 159 the community to evaluate the progress of the transition. The 160 timetable document will also describe procedures to amend the 161 timetable if problems arise in implementing later phases of the 162 transition. It is RECOMMENDED that the timetable document be 163 developed by representatives of the RPKI community, e.g., IANA, 164 Internet Registries, and network operators. 166 3. Terminology 168 This document assumes that the reader is familiar with the terms and 169 concepts described in "Internet X.509 Public Key Infrastructure 170 Certificate and Certificate Revocation List (CRL) Profile" [RFC5280], 171 "X.509 Extensions for IP Addresses and AS Identifiers" [RFC3779], and 172 "A Profile for Resource Certificate Repository Structure" [RFC6481]. 173 Additional terms and conventions used in examples are provided below. 175 Algorithm migration: A planned transition from one signature and 176 hash algorithm to a new signature and hash algorithm. 178 Algorithm Suite A: The "current" algorithm suite used for hashing 179 and signing, in examples in this document 181 Algorithm Suite B: The "next" algorithm suite used for hashing and 182 signing, used in examples in this document 184 CA X: The CA that issued CA Y's certificate (i.e., CA Y's 185 parent), used in examples in this document. 187 CA Y: The non-leaf CA used in examples this document 189 CA Z: A CA that is a "child" of CA Y, used in examples this 190 document 192 Non-Leaf CA: A CA that issues certificates to other CAs is a non- 193 leaf CA. 195 Leaf CA: A leaf CA is a CA that issues only EE certs. 197 PoP (proof of possession): Execution of a protocol that demonstrates 198 to an issuer that a subject requesting a certificate 199 possesses the private key corresponding to the public key 200 in the certificate request submitted by the subject. 202 Signed Product Set (or Set or Product Set): A collection of 203 certificates, signed objects, a CRL and a manifest that 204 are associated by virtue of being verifiable under the 205 same parent CA certificate 207 Correspond: Two certificates, issued under different Algorithm Suites 208 correspond to one another if they are issued to the same 209 entity by the same CA and bind identical Internet Number 210 Resources (INRs) to that entity. Two CRLs correspond if 211 they are issued by the same CA and enumerate 212 corresponding certificates. Two signed objects (other 213 than manifests) correspond if they are verified using 214 corresponding EE certificates and they contain the same 215 encapsulated Context Info field. Two manifests 216 correspond if they encompass corresponding certificates, 217 ROAs, CRLs, and (other) signed objects (the term 218 "equivalent" is used synonymously when referring to such 219 RPKI signed products.) 221 ROA: Route Origination Authorisation, as defined in [RFC6482]. 223 4. Key Rollover steps for algorithm migration 225 The "current" RPKI algorithm suite (Suite A) is defined in the RPKI 226 CP document, by reference to [RFC6485]. When a migration of the RPKI 227 algorithm suite is needed, the first step MUST be an update of 228 [RFC6485] to define the new algorithm suite. The algorithm 229 transition timeline document MUST also be published (as a BCP), to 230 inform the community of the dates selected for milestones in the 231 transition process, as described in Section 4.1. 233 4.1. Milestones definition 235 CA Ready Algorithm B Date: After this date, all (non-leaf) CAs MUST 236 be ready to process a request from a child CA to issue a 237 certificate under the Algorithm Suite B. All CAs 238 publishing an [RFC6490] Trust Anchor Locator (TAL) for 239 Algorithm Suite A, MUST also publish the correspondent 240 TAL for Algorithm Suite B. 242 CA Go Algorithm B Date: After this date, all CAs MUST have reissued 243 all of their signed product sets under the Algorithm 244 Suite B. 246 RP Ready Algorithm B Date: After this date, all RPs MUST be prepared 247 to process signed material issued under the Algorithm 248 Suite B. 250 Twilight Date: After this date, a CA MAY cease issuing signed 251 products under the Algorithm Suite A. Also, after this 252 date, a RP MAY cease to validate signed materials issued 253 under the Algorithm Suite A. 255 End Of Life (EOL) Date: After this date, the Algorithm Suite A MUST 256 be deprecated using the process in Section 10 and all 257 Algorithm Suite A TALs MUST be removed from their 258 publication points. 260 4.2. Process overview 262 The migration process described in this document involves a series of 263 steps that MUST be executed in chronological order by CAs and RPs. 264 The only milestone at which both CAs and RPs take action at the same 265 time is the EOL Date. Due to the decentralized nature of the RPKI 266 infrastructure, it is expected that an algorithm transition will span 267 several years. 269 In order to facilitate the transition, CAs will start issuing 270 certificates using the Algorithm B in a hierarchical top-down 271 fashion. In our example, CA Y will issue certificates using the 272 Algorithm Suite B only after CA X has started to do so (CA Y Ready 273 Algorithm B Date > CA X Ready Algorithm B Date). This ordered 274 transition avoids issuance of "mixed" suite CA certificates, e.g., a 275 CA certificate signed using Suite A, containing a key from Suite B. 276 In the RPKI, a CA MUST NOT sign a CA certificate carrying a subject 277 key that corresponds to an algorithm suite that differs from the one 278 used to sign the certificate. (X.509 accommodates such mixed 279 algorithm certificates, but this process avoids using that 280 capability.) A not top-down transition approach would require use of 281 such mixed mode certificates, and would lead to exponential growth of 282 the RPKI repository. Also, because the RPKI CP mandates Proof of 283 Possession (PoP) for certificate requests, it is not possible for a 284 CA to request a certificate for Algorithm Suite B, until its parent 285 CA supports that Suite. (See Section 5 for more details.) 287 The algorithm agility model described here does not prohibit a CA 288 from issuing an EE certificate with a subject public key from a 289 different algorithm suite, if that certificate is not used to verify 290 repository objects. This exception to the mixed algorithm suite 291 certificate rule is allowed because an EE certificate that is not 292 used to verify repository objects does not interfere with the ability 293 of RPs to download and verify repository content. As noted above, 294 every CA in the RPKI is required to perform a PoP check for the 295 subject public key when issuing a certificate. In general a subject 296 cannot assume that a CA is capable of supporting a different 297 algorithm. However, if the subject is closely affiliated with the 298 CA, it is reasonable to assume that there are ways for the subject to 299 know whether the CA can support a request to issue an EE certificate 300 containing a specific, different public key algorithm. This document 301 does not specify how a subject can determine whether a CA is capable 302 of issuing a mixed suite EE certificate, because it anticipates that 303 such certificates will be issued only in contexts where the subject 304 and CA are sufficiently closely affiliated (for example, an ISP 305 issuing certificates to devices that it manages). 307 The following figure gives an overview of the process: 309 Process for RPKI CAs: 311 Phase 0 Phase 1 Phase 2 Phase 4 Phase 0 312 -----------x---------x-------------------x--------x----------- 313 ^ ^ ^ ^ ^ 314 | | | | | 315 (1) (2) (3) (5) (6) 317 Process for RPKI RPs: 319 Phase 0 Phase 3 Phase 4 Phase 0 320 -------------------------------x---------x--------x----- 321 ^ ^ ^ ^ 322 | | | | 323 (1) (4) (5) (6) 325 (1) RPKI algorithm document is updated and the algorithm transition timeline document is issued 326 (2) CA Ready Algorithm B Date 327 (3) CA Go Algorithm B Date 328 (4) RP Ready Algorithm B Date 329 (5) Twilight Date 330 (6) End Of Live (EOL) Date 332 Each of these milestones is discussed in the next section when 333 describing each phase of the transition process. 335 Two situations have been identified that motivate pausing or rolling 336 back the transition process. The first situation arises if the RPKI 337 community is not ready to make the transition. For example, many CAs 338 might not be prepared to issue signed products under Suite B, or many 339 RPs might not be ready to process Suite B products. Under these 340 circumstances, the timetable MUST be reissued, postponing the date 341 for the phase in question, and pushing back the dates for later 342 phases. The other situation arises if, during the transition, 343 serious concerns arise about the security of the Suite B algorithms. 344 Such concerns would motivate terminating the transition and rolling 345 back signed products, i.e., reverting to Suite A. In this case the 346 timetable MUST be republished, and the RPKI algorithm document MUST 347 be superseded. The phase descriptions below allude to these two 348 situations, as appropriate. 350 4.3. Phase 0 352 Phase 0 is the steady state phase of the process; throughout this 353 phase, Algorithm Suite A is the only supported algorithm suite in 354 RPKI. This is also the steady state for the RPKI. 356 During Phase 0, CAs X, Y and Z are required to generate signed 357 product sets using only the Algorithm Suite A. Also, RPs are required 358 to validate signed product sets issued using only Algorithm Suite A. 360 The following figure shows an example of the structure of signed 361 objects in the repository, indicating the algorithm suites in use, 362 and showing the relationships between three CAs (X, Y, and Z) that 363 form a certification chain. Vertical alignment in the figure 364 indicates objects signed by the same CA using the same private key. 365 The differences in horizontal indentation also represent use of 366 different publication points for objects signed by different CAs. 367 The characters "|->" are used for visualization purposes for both the 368 signing relationship and the publication point change. For example, 369 the objects CA-Y-Certificate-Algorithm-Suite-A, CA-X-CRL-Algorithm- 370 Suite-A and CA-X-Signed-Objects-Algorithm-Suite-A are all signed 371 using the private key corresponding to CA-X-Certificate-Algorithm- 372 Suite-A and published at CA X's corresponding publication point. 374 CA-X-Certificate-Algorithm-Suite-A (Cert-XA) 375 |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA) 376 |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA) 377 |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA) 378 |-> CA-Z-Signed-Objects-Algorithm-Suite-A 379 |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA) 380 |-> CA-Y-Signed-Objects-Algorithm-Suite-A 381 |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA) 382 |-> CA-X-Signed-Objects-Algorithm-Suite-A 384 Note: Cert-XA represent the certificate for CA X, that is signed 385 using the algorithm suite A. 387 4.3.1. Milestone 1 389 The first milestone initiates the migration process. It updates 390 [RFC6485] with the following definitions for the RPKI: 392 o Algorithm Suite A 394 o Algorithm Suite B 396 Additionally, the new algorithm transition timeline document MUST be 397 published with the following information: 399 o CA Ready Algorithm B Date 401 o CA Go Algorithm B Date 403 o RP Ready Algorithm B Date 404 o Twilight Date 406 o EOL Date 408 o Readiness metrics for CAs and RPs in each phase 410 Each date specified here is assumed at one minute after midnight, 411 UTC. No finer granularity time specification is required or 412 supported. 414 4.4. Phase 1 416 Phase 1 starts at the CA Ready Algorithm B Date. During Phase 1, all 417 (non-leaf) CAs MUST be ready to process a request from a child CA to 418 issue or revoke a certificate using the Algorithm Suite B. If it is 419 determined that a substantial number of CAs are not ready, the 420 algorithm transition timeline document MUST be reissued, as noted in 421 Section 4.2. However, CAs that are capable of issuing Suite B 422 certificates may continue to do so, if requested by their child CAs. 423 Since this phase does not require any RPs to process signed objects 424 under Suite B, and since Suite B product sets SHOULD be stored at 425 independent publication points, there is no adverse impact on RPs. 426 If the Suite B algorithm is deemed unsuitable, the algorithm 427 transition timeline and the algorithm specification documents MUST be 428 replaced, the Algorithm Suite B MUST be deprecated using the process 429 described in Section 10. 431 As the transition will happen using a (hierarchic) top-down model, a 432 child CA will be able to issue certificates using the Algorithm Suite 433 B only after its parent CA has issued its own. The RPKI provisioning 434 protocol can identify if a parent CA is capable of issuing 435 certificates using the Algorithm Suite B, and can identify the 436 corresponding algorithm suite in each Certificate Signing Request 437 (see Section 5). During much of this phase the Suite B product tree 438 will be incomplete, i.e., not all CAs will have issued products under 439 Suite B. Thus for production purposes, RPs MUST fetch and validate 440 only Suite A products. Suite B products should be fetched and 441 processed only for testing purposes. 443 The following figure shows the status of repository entries for the 444 three example CAs during this Phase. Two distinct certificate chains 445 are maintained and CA Z has not yet requested any material using the 446 Algorithm Suite B. 448 CA-X-Certificate-Algorithm-Suite-A (Cert-XA) 449 |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA) 450 |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA) 451 |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA) 452 |-> CA-Z-Signed-Objects-Algorithm-Suite-A 453 |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA) 454 |-> CA-Y-Signed-Objects-Algorithm-Suite-A 455 |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA) 456 |-> CA-X-Signed-Objects-Algorithm-Suite-A 458 CA-X-Certificate-Algorithm-Suite-B (Cert-XB) 459 |-> CA-Y-Certificate-Algorithm-Suite-B (Cert-YB) 460 |-> CA-Y-CRL-Algorithm-Suite-B (CRL-YB) 461 |-> CA-Y-Signed-Objects-Algorithm-Suite-B 462 |-> CA-X-CRL-Algorithm-Suite-B (CRL-XB) 463 |-> CA-X-Signed-Objects-Algorithm-Suite-B 465 4.5. Phase 2 467 Phase 2 starts at the CA Go Algorithm B Date. At the start of this 468 phase, each signed product set MUST be available using both Algorithm 469 Suite A and Algorithm Suite B. Thus, prior to the start of this 470 phase, every CA MUST ensure that there is a Suite B product 471 corresponding to each Suite A product that the CA has issued. 472 Throughout this Phase, each CA MUST maintain this correspondence. 473 During this phase, RPs MUST be prepared to validate sets issued using 474 Algorithm Suite A and MAY be prepared to validate sets issued using 475 the Algorithm Suite B. 477 If it is determined that a substantial number of CAs are not ready, 478 the algorithm transition timeline document MUST be reissued, as noted 479 in Section 4.2. (Since the processing requirement for RPs here is a 480 MAY, if RPs have problems with Suite B products this does not require 481 pushing back the Phase 2 milestone, but it does motivate delaying the 482 start of Phase 3.) CAs that are capable of publishing products under 483 Suite B MAY continue to do so. Phase 2, like Phase 1, does not 484 require any RPs to process signed objects under Suite B. Also, Suite 485 B product SHOULD be stored at independent publication points, so 486 there is no adverse impact on RPs that are not prepared to process 487 suite B products (See Section 9 for additional details.) If the 488 Suite B algorithm is deemed unsuitable, the algorithm transition 489 timeline and the algorithm specification documents MUST be replaced 490 and the Algorithm Suite B MUST be deprecated using the process 491 described in Section 10. 493 It is RECOMMENDED that RPs that can process Algorithm Suite B fetch 494 and validate Suite B products. RPs that are not ready to process 495 Suite B products MUST continue to make use of Suite A products. An 496 RP that elects to validate signed product sets using both Algorithm 497 Suite A or Algorithm Suite B should expect the same results. If 498 there are discrepancies when evaluating corresponding signed product 499 sets, successful validation of either product set is acceptable. A 500 detailed analysis of the validation of multiple instances of signed 501 objects is included in Section 6. 503 The following figure shows the status of the repository entries for 504 the three example CAs throughout this phase, where all signed objects 505 are available using both algorithm suites. 507 CA-X-Certificate-Algorithm-Suite-A (Cert-XA) 508 |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA) 509 |-> CA-Z-Certificate-Algorithm-Suite-A (Cert-ZA) 510 |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZA) 511 |-> CA-Z-Signed-Objects-Algorithm-Suite-A 512 |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA) 513 |-> CA-Y-Signed-Objects-Algorithm-Suite-A 514 |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA) 515 |-> CA-X-Signed-Objects-Algorithm-Suite-A 517 CA-X-Certificate-Algorithm-Suite-B (Cert-XB) 518 |-> CA-Y-Certificate-Algorithm-Suite-B (Cert-YB) 519 |-> CA-Z-Certificate-Algorithm-Suite-B (Cert-ZB) 520 |-> CA-Z-CRL-Algorithm-Suite-B (CRL-ZB) 521 |-> CA-Z-Signed-Objects-Algorithm-Suite-B 522 |-> CA-Y-CRL-Algorithm-Suite-B (CRL-YB) 523 |-> CA-Y-Signed-Objects-Algorithm-Suite-B 524 |-> CA-X-CRL-Algorithm-Suite-B (CRL-XB) 525 |-> CA-X-Signed-Objects-Algorithm-Suite-B 527 4.6. Phase 3 529 Phase 3 starts at the RP Ready Algorithm B Date. During this phase, 530 all signed product sets are available using both algorithm suites and 531 all RPs MUST be able to validate them. (The correspondence between 532 Suite A and Suite B products was required for Phase 2, and maintained 533 throughout that Phase. The same requirements apply throughout this 534 Phase.) It is RECOMMENDED that, in preparation for Phase 4, RPs 535 retrieve and process Suite B product sets first, and treat them as 536 the preferred product sets for validation throughout this phase. 537 Thus an RP SHOULD try to validate the sets of signed products 538 retrieved from the Algorithm Suite B repository first. 540 If a substantial number of RPs are unable to process product sets 541 signed with Suite B, the algorithm transition timeline document MUST 542 be reissued, pushing back the date for this and later milestones, as 543 discussed in Section 4.2. Since the Suite B products SHOULD be 544 published at distinct publication points, RPs that cannot process 545 Suite B products can be expected to revert to the Suite A products 546 that still exist. If the Suite B algorithm is deemed unsuitable, the 547 algorithm transition timeline and the algorithm specification 548 documents MUST be replaced and the Algorithm Suite B MUST be 549 deprecated using the process described in Section 10. 551 There are no changes to the CA behavior throughout this phase. 553 4.7. Phase 4 555 Phase 4 starts at the Twilight Date. At that date, the Algorithm A 556 is labeled as "old" and the Algorithm B is labeled as "current". 558 During this phase, all signed product sets MUST be issued using 559 Algorithm Suite B and MAY be issued using Algorithm Suite A. All 560 signed products sets issued using Suite B MUST be published at their 561 corresponding publication points. Signed products sets issued using 562 Suite A might not be available at their corresponding publication 563 points. Every RP MUST validate signed product sets using Suite B. 564 RPs MAY validate signed product sets using Suite A. However, RPs 565 SHOULD NOT assume that the collection of Suite A product sets is 566 complete. Thus RPs SHOULD make use of only Suite B products sets. 567 (See Section 6 for further details.) 569 If it is determined that many RPs are not capable of processing the 570 new algorithm suite, the algorithm transition timeline document MUST 571 be reissued pushing back the date for this and the next milestone. 572 The document MUST require CA to not remove Suite A product sets if 573 this phase is delayed. If the Algorithm Suite B is deemed 574 unsuitable, the algorithm transition timeline, the algorithm 575 specification documents MUST be replaced, the Algorithm Suite B MUST 576 be deprecated using the process described in Section 10 and CAs MUST 577 NOT remove Suite A product sets. At this stage, RPs are still 578 capable of processing Suite A signed products, so the RPKI is still 579 viable. 581 The following figure describes a possible status for the repositories 582 of the example CAs. 584 CA-X-Certificate-Algorithm-Suite-A (Cert-XA) 585 |-> CA-Y-Certificate-Algorithm-Suite-A (Cert-YA) 586 |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YA) 587 |-> CA-Y-Signed-Objects-Algorithm-Suite-A 588 |-> CA-X-CRL-Algorithm-Suite-A (CRL-XA) 589 |-> CA-X-Signed-Objects-Algorithm-Suite-A 591 CA-X-Certificate-Algorithm-Suite-B (Cert-XB) 592 |-> CA-Y-Certificate-Algorithm-Suite-B (Cert-YB) 593 |-> CA-Z-Certificate-Algorithm-Suite-B (Cert-ZB) 594 |-> CA-Z-CRL-Algorithm-Suite-A (CRL-ZB) 595 |-> CA-Z-Signed-Objects-Algorithm-Suite-B 596 |-> CA-Y-CRL-Algorithm-Suite-A (CRL-YB) 597 |-> CA-Y-Signed-Objects-Algorithm-Suite-B 598 |-> CA-X-CRL-Algorithm-Suite-A (CRL-XB) 599 |-> CA-X-Signed-Objects-Algorithm-Suite-B 601 4.8. Return to Phase 0 603 The EOL Date triggers the return to Phase 0 (steady state). At this 604 point, the old algorithm suite (Algorithm Suite A) MUST be deprecated 605 using the process described in Section 10. 607 This phase closes the loop as the new algorithm suite (Algorithm 608 Suite B) is the only required algorithm suite in RPKI. From this 609 point forward, this suite is referred to as Algorithm Suite A. 611 If it is determined that many RPs are not capable of processing the 612 new algorithm suite, the algorithm transition timeline document MUST 613 be reissued pushing back the date for this milestone. 615 5. Multi Algorithm support in the RPKI provisioning protocol 617 The migration described in this document is a top-down process, where 618 two synchronization issues need to be solved between child and parent 619 CAs: 621 o A child CA needs to identify which algorithm suites are supported 622 by its parent CA 624 o A child CA needs to signal which algorithm suite should be used by 625 its parent CA to sign a Certificate Signing Request (CSR) 627 The RPKI provisioning protocol [RFC6492] supports multiple algorithms 628 suites by implementing different resource classes for each suite. 629 Several different resource classes also may use the same algorithm 630 suite for different resource sets. 632 A child CA that wants to identify which algorithm suites are 633 supported by its parent CA MUST perform the following tasks: 635 1. Establish a provisioning protocol session with its parent CA 637 2. Perform a "list" command as described in Section 3.3.1 of 638 [RFC6492] 640 3. From the Payload in the "list response" resource class, extract 641 the "issuer's certificate" for each class. The Algorithm Suite 642 for each class will match the Algorithm Suite used to issue the 643 corresponding "issuer's certificate" (as specified in the 644 SubjectPublicKeyInfo field of that certificate) 646 A child CA that wants to specify an Algorithm Suite to its parent CA 647 (e.g., in a certificate request) MUST perform the following tasks: 649 1. Perform the tasks described above to identify the algorithm 650 suites supported by its parent CA, and the resource class 651 corresponding to each suite 653 2. Identify the corresponding resource class in the appropriate 654 provisioning protocol command (e.g. "issue" or "revoke") 656 Upon receipt of a certificate request from a child CA, a parent CA 657 will verify the PoP of the private key. If a child CA requests 658 issuing a certificate using an algorithm suite that does not match a 659 resource class, the PoP validation will fail and the request will not 660 be performed. 662 6. Validation of multiple instance of signed products 664 During Phases 1,2,3 and 4, two algorithm suites will be valid 665 simultaneously in RPKI. In this section, we describe the RP behavior 666 when validating corresponding signed products using different 667 algorithm suites. 669 During Phase 1 two (corresponding) instances MAY be available for 670 each signed product, one signed under Algorithm Suite A and one under 671 Algorithm Suite B. As noted in Section 4.4, in this phase there is a 672 preference for Suite A product sets. All products are available 673 under Suite A, while only some products may be available under Suite 674 B. For production purposes an RP MAY fetch and validate only Suite A 675 products. Suite B products SHOULD be fetched and validated only for 676 test purposes. When product sets exist under both Suites, they 677 should yield equivalent results, which facilitates testing. (It is 678 not possible to directly compare Suite A and Suite B product sets, as 679 certs, CRLs, and manifests will appear syntactically different. 680 However, the output of the process, i.e., the ROA payloads 681 (Autonomous System Number and address prefix data), SHOULD match, 682 modulo timing issues.) 684 During Phases 2 and 3 of this process, two (corresponding) instances 685 of all signed products MUST be available to RPs. As noted in Section 686 4.5, it is RECOMMENDED that Suite B capable RPs fetch and validate 687 Suite B products sets, during Phase 2. If an RP encounters 688 validation problems with the Suite B products, it SHOULD revert to 689 using Suite A products. RPs that are Suite B capable MAY fetch both 690 product sets and compare the results (e.g., ROA outputs) for testing. 692 In Phase 3 all RPs MUST be Suite B capable, and MUST fetch Suite B 693 product sets. If an RP encounters problems with Suite B product 694 sets, it can revert to Suite A products. RPs encountering such 695 problems SHOULD contact the relevant repository maintainers (e.g., 696 using the mechanism defined in [RFC6493] to report problems.) 698 During Phase 4 only Suite B product sets are required to be present 699 for all RPKI entities, as per Section 4.7. Thus RPs SHOULD retrieve 700 and validate only these product sets. Retrieval of Suite A products 701 sets may yield an incomplete set of signed products and is NOT 702 RECOMMENDED. 704 7. Revocation 706 The algorithm migration process mandates the maintenance of two 707 parallel but equivalent certification hierarchies during Phases 2 and 708 3 of the process. During these phases, a CA MUST revoke and request 709 revocation of certificates consistently under both algorithm Suites. 710 When not performing a key rollover operation (as described in Section 711 8), a CA requesting the revocation of its certificate during these 712 two phases MUST perform that request for both algorithm suites (A and 713 B). A non-leaf CA SHOULD NOT verify that its child CAs comply with 714 this requirement. Note that a CA MUST request revocation of its 715 certificate relative to a specific algorithm suite using the 716 mechanism described in Section 5 718 During Phase 1, a CA that revokes a certificate under Suite A SHOULD 719 revoke the corresponding certificate under Suite B, if that 720 certificate exists. During Phase 4, a CA that revokes a certificate 721 under Suite B SHOULD revoke the corresponding certificate under Suite 722 A, if that certificate exists. 724 During Phase 1, a CA may revoke certificates under Suite B without 725 revoking them under Suite A, since the Suite B products are for test 726 purposes. During Phase 4 a CA may revoke certificates issued under 727 Suite A without revoking them under Suite B, since Suite A products 728 are being deprecated. 730 8. Key rollover 732 Key rollover (without algorithm changes) is effected independently 733 for each algorithm suite and MUST follow the process described in 734 [RFC6489]. 736 9. Repository structure 738 The two parallel hierarchies that will exist during the transition 739 process SHOULD have independent publications points. The repository 740 structures for each algorithm suite are described in [RFC6481]. 742 10. Deprecating an Algorithm Suite 744 To deprecate an algorithm suite, the following process MUST be 745 executed by every CA in the RPKI: 747 1. Each CA MUST cease issuing certificates under the suite. This 748 means that any request for a (CA) certificate from a child will 749 be rejected, e.g., sending an error_response message with error 750 code:"request - no such resource class" as defined in [RFC6492]. 752 2. Each CA MUST cease generating signed products, except the CRL and 753 Manifest, under the deprecated Algorithm Suite. 755 3. Each CA MUST revoke the EE certificates for all signed products 756 that it has issued under the deprecated Algorithm Suite. The CA 757 SHOULD delete these products from its publication point, to avoid 758 burdening RPs with downloading and processing these products. 760 4. Each CA MUST revoke all CA certificates that it has issued under 761 the deprecated Algorithm Suite. 763 5. Each CA SHOULD remove all CA certificates that it has issued 764 under the deprecated Algorithm Suite. 766 6. Each CA that publishes a TAL under the deprecated Algorithm Suite 767 MUST removed it from the TAL's publication point. 769 7. Each CA SHOULD continue to maintain the publication point for the 770 deprecated Algorithm Suite, maintained at least until the CRL 771 nextUpdate. This publication point MUST contain only the CRL and 772 a Manifest for that publication point. This behavior provides a 773 window in which RPs may be able to become aware of the revoked 774 status of the signed products that have been deleted. 776 8. Each RP MUST remove any TALs that is has published under the 777 deprecated Algorithm Suite. 779 CAs in the RPKI hierarchy may become aware of the deprecation of the 780 algorithm suite at different times, and may execute the procedure 781 above in an asynchronous fashion relative to one another. Thus, for 782 example, a CA may request revocation of its CA certificate only to 783 learn that the certificate has already been revoked by the issuing 784 CA. The revocation of a CA certificate makes the CRL and manifest 785 issued under it incapable of validation. The asynchronous execution 786 of this procedure likely will result in transient "inconsistencies" 787 among the publication points associated with the deprecated algorithm 788 suite. However, these inconsistencies should yield "fail safe" 789 results, i.e., the objects signed under the deprecated suite should 790 be rejected by RPs. 792 11. IANA Considerations 794 No IANA requirements 796 12. Security Considerations 798 An algorithm transition in RPKI should be a very infrequent event and 799 it requires wide community consensus. The events that may lead to an 800 algorithm transition may be related to a weakness of the 801 cryptographic strength of the algorithm suite in use by RPKI, which 802 is normal to happen over time. The procedure described in this 803 document will take years to complete an algorithm transition. During 804 that time, the RPKI system will be vulnerable to any cryptographic 805 weakness that may have triggered this procedure (i.e. downgrade 806 attack). 808 This document does not describe an emergency mechanism for algorithm 809 migration. Due to the distributed nature of RPKI, and the very large 810 number of CAs and RPs, the authors do not believe it is feasible to 811 effect an emergency algorithm migration procedure. 813 If a CA does not complete its migration to the new algorithm suite as 814 described in this document (after the EOL of the "old" algorithm 815 suite), its signed product set will no longer be valid. 816 Consequently, the RPKI may, at the end of Phase 4, have a smaller 817 number of valid signed products than before starting the process. 818 Conversely, a RP that does not follow this process will lose the 819 ability to validate signed products issued under the new algorithm 820 suite. The resulting incomplete view of routing info from the RPKI 821 (as a result of a failure by CAs or RPs to complete the transition) 822 could degrade routing in the public Internet. 824 13. Acknowledgements 826 The authors would like to acknowledge the work of the SIDR working 827 group co-chairs (Sandra Murphy and Chris Morrow) as well as the 828 contributions given by Geoff Huston, Arturo Servin, Brian Weis, Terry 829 Manderson, Brian Dickson and Danny McPherson. 831 14. Normative References 833 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 834 Requirement Levels", BCP 14, RFC 2119, March 1997. 836 [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP 837 Addresses and AS Identifiers", RFC 3779, June 2004. 839 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 840 Housley, R., and W. Polk, "Internet X.509 Public Key 841 Infrastructure Certificate and Certificate Revocation List 842 (CRL) Profile", RFC 5280, May 2008. 844 [RFC6481] Huston, G., Loomans, R., and G. Michaelson, "A Profile for 845 Resource Certificate Repository Structure", RFC 6481, 846 February 2012. 848 [RFC6482] Lepinski, M., Kent, S., and D. Kong, "A Profile for Route 849 Origin Authorizations (ROAs)", RFC 6482, February 2012. 851 [RFC6484] Kent, S., Kong, D., Seo, K., and R. Watro, "Certificate 852 Policy (CP) for the Resource Public Key Infrastructure 853 (RPKI)", BCP 173, RFC 6484, February 2012. 855 [RFC6485] Huston, G., "The Profile for Algorithms and Key Sizes for 856 Use in the Resource Public Key Infrastructure (RPKI)", 857 RFC 6485, February 2012. 859 [RFC6489] Huston, G., Michaelson, G., and S. Kent, "Certification 860 Authority (CA) Key Rollover in the Resource Public Key 861 Infrastructure (RPKI)", BCP 174, RFC 6489, February 2012. 863 [RFC6490] Huston, G., Weiler, S., Michaelson, G., and S. Kent, 864 "Resource Public Key Infrastructure (RPKI) Trust Anchor 865 Locator", RFC 6490, February 2012. 867 [RFC6492] Huston, G., Loomans, R., Ellacott, B., and R. Austein, "A 868 Protocol for Provisioning Resource Certificates", 869 RFC 6492, February 2012. 871 [RFC6493] Bush, R., "The Resource Public Key Infrastructure (RPKI) 872 Ghostbusters Record", RFC 6493, February 2012. 874 Appendix A. Change Log 876 Note to the RFC Editor: Please remove this section before 877 publication. 879 From 10 to 11 881 Additional GenArt review on section 4 to improve the description of 882 the figures showing the CAs chains. 884 From 09 to 10 886 1. GenArt Comments: Remove Algorithm C from process and replace a 887 couple of "will" with MUST when referring to issuing a new 888 document. 890 From 08 to 09 892 1. SecDIR comments and nits included 894 From 07 to 08 896 1. Typo in Section 10 898 2. Correct reference for RFC6493 900 From 06 to 07: 902 1. Added definition for "Correspond" 904 2. Added reference of correspondence between suites in phase 2 and 3 906 3. Small nit on the revocation definition. 908 From 05 to 06: 910 1. Added reference to published RFCs 912 2. Removed requirement on dates format 914 3. Changed revocation section to emphasize the differences between 915 phase 1,2,3 and 4. 917 4. Added Section 10: Deprecating an Algorithm Suite 919 5. Typos and editoral changes 921 From 04 to 05: 923 1. WGLC nits 925 From 03 to 04: 927 1. Added text for "roll-over" capability in each phase 929 2. Added the requirement for splitting the milestone 1 in two 930 documents: the update of the alg document and a new document 931 specifying the particular timelines 933 3. WGLC nits 935 From 02 to 03: 937 1. Explicitely named than "mixed" certificates are not allowed for 938 CA certs but may be possible for EE certs that are not used to 939 validate repository objects. 941 From 01 to 02: 943 1. Add reference to Multi-Objects validation 945 2. EOL Date is the only milestone that RP and CA take actions "at 946 the same time". 948 3. Updated references 950 4. Editorial 952 From 00 to 01: 954 1. Include text to clarify former Suites 956 2. Include text that documents that an RP that validates an object 957 signed with either suites in Phase 2 MUST consider it as valid 959 From individual submission to WG item: 961 1. Change form "laisez faire" to "top-down" 963 2. Included Multi Algorithm support in the RPKI provisioning 964 protocol 966 3. Included Validation of multiple instance of signed products 968 4. Included Revocations 969 5. Included Key rollover 971 6. Included Repository structure 973 7. Included Security Considerations 975 8. Included Acknowledgements 977 Authors' Addresses 979 Roque Gagliano 980 Cisco Systems 981 Avenue des Uttins 5 982 Rolle, 1180 983 Switzerland 985 Email: rogaglia@cisco.com 987 Stephen Kent 988 BBN Technologies 989 10 Moulton St. 990 Cambridge, MA 02138 991 USA 993 Email: kent@bbn.com 995 Sean Turner 996 IECA, Inc. 997 3057 Nutley Street, Suite 106 998 Fairfax, VA 22031 999 USA 1001 Email: turners@ieca.com