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Checking references for intended status: Experimental ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 4843 (Obsoleted by RFC 7343) ** Obsolete normative reference: RFC 5201 (Obsoleted by RFC 7401) ** Obsolete normative reference: RFC 5996 (Obsoleted by RFC 7296) Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Host Identity Protocol Heer 3 Internet-Draft Communication and Distributed 4 Updates: 5201 (if approved) Systems, RWTH Aachen University 5 Intended status: Experimental Varjonen 6 Expires: September 10, 2011 Helsinki Institute for Information 7 Technology 8 March 9, 2011 10 Host Identity Protocol Certificates 11 draft-ietf-hip-cert-11 13 Abstract 15 The CERT parameter is a container for digital certificates. It is 16 used for carrying these certificates in Host Identity Protocol (HIP) 17 control packets. This document specifies the certificate parameter 18 and the error signaling in case of a failed verification. 19 Additionally, this document specifies the representations of Host 20 Identity Tags in X.509 version 3 (v3) and SPKI certificates. 22 The concrete use of certificates including how certificates are 23 obtained, requested, and which actions are taken upon successful or 24 failed verification are specific to the scenario in which the 25 certificates are used. Hence, the definition of these scenario- 26 specific aspects are left to the documents that use the CERT 27 parameter. 29 This document updates RFC 5201. 31 Status of this Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on September 10, 2011. 48 Copyright Notice 49 Copyright (c) 2011 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 This document may contain material from IETF Documents or IETF 63 Contributions published or made publicly available before November 64 10, 2008. The person(s) controlling the copyright in some of this 65 material may not have granted the IETF Trust the right to allow 66 modifications of such material outside the IETF Standards Process. 67 Without obtaining an adequate license from the person(s) controlling 68 the copyright in such materials, this document may not be modified 69 outside the IETF Standards Process, and derivative works of it may 70 not be created outside the IETF Standards Process, except to format 71 it for publication as an RFC or to translate it into languages other 72 than English. 74 1. Introduction 76 Digital certificates bind pieces of information to a public key by 77 means of a digital signature, and thus, enable the holder of a 78 private key to generate cryptographically verifiable statements. The 79 Host Identity Protocol (HIP) [RFC5201] defines a new cryptographic 80 namespace based on asymmetric cryptography. The identity of each 81 host is derived from a public key, allowing hosts to digitally sign 82 data and issue certificates with their private key. This document 83 specifies the CERT parameter, which is used to transmit digital 84 certificates in HIP. It fills the placeholder specified in Section 85 5.2 of [RFC5201], and thus, updates [RFC5201]. 87 1.1. Requirements Language 89 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 90 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 91 "OPTIONAL" in this document are to be interpreted as described in RFC 92 2119 [RFC2119]. 94 2. CERT Parameter 96 The CERT parameter is a container for certain types of digital 97 certificates. It does not specify any certificate semantics. 98 However, it defines supplementary parameters that help HIP hosts to 99 transmit semantically grouped CERT parameters in a more systematic 100 way. The specific use of the CERT parameter for different use cases 101 is intentionally not discussed in this document because it is 102 specific to a concrete use case. Hence, the use of the CERT 103 parameter will be defined in the documents that use the CERT 104 parameter. 106 The CERT parameter is covered and protected, when present, by the HIP 107 SIGNATURE field and is a non-critical parameter. 109 The CERT parameter can be used in all HIP packets. However, using it 110 in the first Initiator (I1) packet is NOT RECOMMENDED because it can 111 increase the processing times of I1s, which can be problematic when 112 processing storms of I1s. Each HIP control packet MAY contain 113 multiple CERT parameters. These parameters MAY be related or 114 unrelated. Related certificates are managed in Cert groups. A Cert 115 group specifies a group of related CERT parameters that SHOULD be 116 interpreted in a certain order (e.g., for expressing certificate 117 chains). For grouping CERT parameters, the Cert group and the Cert 118 count field MUST be set. Ungrouped certificates exhibit a unique 119 Cert group field and set the Cert count to 1. CERT parameters with 120 the same Cert group number in the group field indicate a logical 121 grouping. The Cert count field indicates the number of CERT 122 parameters in the group. 124 CERT parameters that belong to the same Cert group MAY be contained 125 in multiple sequential HIP control packets. This is indicated by a 126 higher Cert count than the amount of CERT parameters with matching 127 Cert group fields in a HIP control packet. The CERT parameters MUST 128 be placed in ascending order, within a HIP control packet, according 129 to their Cert group field. Cert groups MAY only span multiple 130 packets if the Cert group does not fit the packet. A HIP packet MUST 131 NOT contain more than one incomplete Cert group that continues in the 132 next HIP control packet. 134 The Cert ID acts as a sequence number to identify the certificates in 135 a Cert group. The numbers in the Cert ID field MUST start from 1 up 136 to Cert count. 138 The Cert Group and Cert ID namespaces are managed locally by each 139 host that sends CERT parameters in HIP control packets. 141 0 1 2 3 142 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 | Type | Length | 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | Cert group | Cert count | Cert ID | Cert type | 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 | Certificate / 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 / | Padding | 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 153 Type 768 154 Length Length in octets, excluding Type, Length, and Padding 155 Cert group Group ID grouping multiple related CERT parameters 156 Cert count Total count of certificates that are sent, possibly 157 in several consecutive HIP control packets. 158 Cert ID The sequence number for this certificate 159 Cert Type Indicates the type of the certificate 160 Padding Any Padding, if necessary, to make the TLV a multiple 161 of 8 bytes. 163 The certificates MUST use the algorithms defined in [RFC5201] as the 164 signature and hash algorithms. 166 The following certificate types are defined: 168 +--------------------------------+-------------+ 169 | Cert format | Type number | 170 +--------------------------------+-------------+ 171 | Reserved | 0 | 172 | X.509 v3 | 1 | 173 | SPKI | 2 | 174 | Hash and URL of X.509 v3 | 3 | 175 | Hash and URL of SPKI | 4 | 176 | LDAP URL of X.509 v3 | 5 | 177 | LDAP URL of SPKI | 6 | 178 | Distinguished Name of X.509 v3 | 7 | 179 | Distinguished Name of SPKI | 8 | 180 +--------------------------------+-------------+ 182 The next sections outline the use of Host Identity Tags (HITs) in 183 X.509 v3 and in Simple Public Key Infrastructure (SPKI) certificates. 184 X.509 v3 certificates and the handling procedures are defined in 185 [RFC5280]. The wire format for X.509 v3 is Distinguished Encoding 186 Rules format as defined in [X.690]. The SPKI, the handling 187 procedures, and the formats are defined in [RFC2693]. 189 Hash and Uniform Resource Locator (URL) encodings (3 and 4) are used 190 as defined in [RFC5996] Section 3.6. Using hash and URL encodings 191 results in smaller HIP control packets, but requires the receiver to 192 resolve the URL or check a local cache against the hash. 194 LDAP URL encodings (5 and 6) are used as defined in [RFC4516]. Using 195 LDAP URL encoding results in smaller HIP control packets but requires 196 the receiver to retrieve the certificate or check a local cache 197 against the URL. 199 Distinguished name (DN) encodings (7 and 8) are used as defined in 200 [RFC4514]. Using the DN encoding results in smaller HIP control 201 packets, but requires the receiver to retrieve the certificate or 202 check a local cache against the DN. 204 3. X.509 v3 Certificate Object and Host Identities 206 HITs can represent an issuer, a subject, or both in x.509 v3. HITs 207 are represented as IPv6 addresses as defined in [RFC4843]. When Host 208 Identifier ( HI ) is used to sign the certificate the respective HIT 209 MUST be placed in to the Issuer Alternative Name (IAN) extension 210 using the GeneralName form iPAddress as defined in [RFC5280]. When 211 the certificate is issued for a HIP host, identified by a HIT and HI, 212 the respective HIT MUST be placed in to the Subject Alternative Name 213 (SAN) extension using the GeneralName form iPAddress and the full HI 214 is presented as the subjects public key info as defined in [RFC5280]. 216 The following examples illustrate how HITs are presented as issuer 217 and subject in the X.509 v3 extension alternative names. 219 Format of X509v3 extensions: 220 X509v3 Issuer Alternative Name: 221 IP Address:hit-of-issuer 222 X509v3 Subject Alternative Name: 223 IP Address:hit-of-subject 225 Example X509v3 extensions: 226 X509v3 Issuer Alternative Name: 227 IP Address:2001:14:6cf:fae7:bb79:bf78:7d64:c056 228 X509v3 Subject Alternative Name: 229 IP Address:2001:1C:5a14:26de:a07C:385b:de35:60e3 231 Appendix B shows a full example X.509 v3 certificate with HIP 232 content. 234 As another example, consider a managed Public Key Infrastructure 235 (PKI) environment in which the peers have certificates that are 236 anchored in (potentially different) managed trust chains. In this 237 scenario, the certificates issued to HIP hosts are signed by 238 intermediate Certificate Authorities (CAs) up to a root CA. In this 239 example, the managed PKI environment is neither HIP aware, nor can it 240 be configured to compute HITs and include them in the certificates. 242 When HIP communications are established, the HIP hosts not only need 243 to send their identity certificates (or pointers to their 244 certificates), but also the chain of intermediate CAs (or pointers to 245 the CAs) up to the root CA, or to a CA that is trusted by the remote 246 peer. This chain of certificates MUST be sent in a Cert group as 247 specified in Section 2. The HIP peers validate each other's 248 certificates and compute peer HITs based on the certificate public 249 keys. 251 4. SPKI Cert Object and Host Identities 253 When using SPKI certificates to transmit information related to HIP 254 hosts, HITs need to be enclosed within the certificates. HITs can 255 represent an issuer, a subject, or both. In the following we define 256 the representation of those identifiers for SPKI given as 257 S-expressions. Note that the S-expressions are only the human- 258 readable representation of SPKI certificates. Full HIs are presented 259 in the public key sequences of SPKI certificates. 261 As an example the Host Identity Tag of a host is expressed as 262 follows: 264 Format: (hash hit hit-of-host) 265 Example: (hash hit 2001:13:724d:f3c0:6ff0:33c2:15d8:5f50) 267 Appendix A shows a full example SPKI certificate with HIP content. 269 5. Revocation of Certificates 271 Revocation of X.509 v3 certificates is handled as defined in Section 272 5 of [RFC5280]. Revocation of SPKI certificates is handled as 273 defined in Section 5 of [RFC2693]. 275 6. Error signaling 277 If the Initiator does not send the certificate that the Responder 278 requires the Responder may take actions (e.g. reject the connection). 280 The Responder MAY signal this to the Initiator by sending a HIP 281 NOTIFY message with NOTIFICATION parameter error type 282 CREDENTIALS_NEEDED. 284 If the verification of a certificate fails, a verifier MAY signal 285 this to the provider of the certificate by sending a HIP NOTIFY 286 message with NOTIFICATION parameter error type INVALID_CERTIFICATE. 288 NOTIFICATION PARAMETER - ERROR TYPES Value 289 ------------------------------------ ----- 291 CREDENTIALS_REQUIRED 48 293 The Responder is unwilling to set up an association 294 as the Initiator did not send the needed credentials. 296 INVALID_CERTIFICATE 50 298 Sent in response to a failed verification of a certificate. 299 Notification Data MAY contain n groups of 2 octets (n calculated 300 from the NOTIFICATION parameter length), in order Cert group and 301 Cert ID of the certificate parameter that caused the failure. 303 7. IANA Considerations 305 This document defines the CERT parameter for the Host Identity 306 Protocol [RFC5201]. This parameter is defined in Section 2 with type 307 768. The parameter type number is also defined in [RFC5201]. 309 The CERT parameter has 8-bit unsigned integer field for different 310 certificate types, for which IANA is to create and maintain a new 311 sub-registry entitled "HIP certificate types" under the "Host 312 Identity Protocol (HIP) Parameters". Initial values for the 313 Certificate type registry are given in Section 2. New values for the 314 Certificate types from the unassigned space are assigned through IETF 315 Review. 317 In Section 6 this document defines two new types for "NOTIFY message 318 types" sub-registry under "Host Identity Protocol (HIP) Parameters". 320 8. Security Considerations 322 Certificate grouping allows the certificates to be sent in multiple 323 consecutive packets. This might allow similar attacks as IP-layer 324 fragmentation allows, for example sending of fragments in wrong order 325 and skipping some fragments to delay or stall packet processing by 326 the victim in order to use resources (e.g. CPU or memory). Hence, 327 hosts SHOULD implement mechanisms to discard certificate groups with 328 outstanding certificates if state space is scarce. 330 Checking of the URL and LDAP entries might allow DoS attacks, where 331 the target host may be subjected to bogus work. 333 Security considerations for SPKI certificates are discussed in 334 [RFC2693] and for X.509 v3 in [RFC5280] 336 9. Acknowledgements 338 The authors would like to thank A. Keranen, D. Mattes, M. Komu and T. 339 Henderson for the fruitful conversations on the subject. D. Mattes 340 most notably contributed the non-HIP aware use case in Section 3. 342 10. Normative References 344 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 345 Requirement Levels", BCP 14, RFC 2119, March 1997. 347 [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, 348 B., and T. Ylonen, "SPKI Certificate Theory", RFC 2693, 349 September 1999. 351 [RFC4514] Zeilenga, K., "Lightweight Directory Access Protocol 352 (LDAP): String Representation of Distinguished Names", 353 RFC 4514, June 2006. 355 [RFC4516] Smith, M. and T. Howes, "Lightweight Directory Access 356 Protocol (LDAP): Uniform Resource Locator", RFC 4516, 357 June 2006. 359 [RFC4843] Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix 360 for Overlay Routable Cryptographic Hash Identifiers 361 (ORCHID)", RFC 4843, April 2007. 363 [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, 364 "Host Identity Protocol", RFC 5201, April 2008. 366 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 367 Housley, R., and W. Polk, "Internet X.509 Public Key 368 Infrastructure Certificate and Certificate Revocation List 369 (CRL) Profile", RFC 5280, May 2008. 371 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 372 "Internet Key Exchange Protocol Version 2 (IKEv2)", 373 RFC 5996, September 2010. 375 [X.690] ITU-T, "Recommendation X.690 (2002) | ISO/IEC 8825-1:2002, 376 Information Technology - ASN.1 encoding rules: 377 Specification of Basic Encoding Rules (BER), Canonical 378 Encoding Rules (CER) and Distinguished Encoding Rules 379 (DER)", July 2002. 381 Appendix A. SPKI certificate example 383 This section shows a SPKI certificate with encoded HITs. The example 384 has been indented for readability. 386 (sequence 387 (public_key 388 (rsa-pkcs1-sha1 389 (e #010001#) 390 (n |yDwznOwX0w+zvQbpWoTnfWrUPLKW2NFrpXbsIcH/QBSLb 391 k1RKTZhLasFwvtSHAjqh220W8gRiQAGIqKplyrDEqSrJp 392 OdIsHIQ8BQhJAyILWA1Sa6f5wAnWozDfgdXoKLNdT8ZNB 393 mzluPiw4ozc78p6MHElH75Hm3yHaWxT+s83M=| 394 ) 395 ) 396 ) 397 (cert 398 (issuer 399 (hash hit 2001:15:2453:698a:9aa:253a:dcb5:981e) 400 ) 401 (subject 402 (hash hit 2001:12:ccd6:4715:72a3:2ab1:77e4:4acc) 403 ) 404 (not-before "2011-01-12_13:43:09") 405 (not-after "2011-01-22_13:43:09") 406 ) 407 (signature 408 (hash sha1 |h5fC8HUMATTtK0cjYqIgeN3HCIMA|) 409 |u8NTRutINI/AeeZgN6bngjvjYPtVahvY7MhGfenTpT7MCgBy 410 NoZglqH5Cy2vH6LrQFYWx0MjWoYwHKimEuBKCNd4TK6hrCyAI 411 CIDJAZ70TyKXgONwDNWPOmcc3lFmsih8ezkoBseFWHqRGISIm 412 MLdeaMciP4lVfxPY2AQKdMrBc=| 413 ) 414 ) 416 Appendix B. X.509.v3 certificate example 418 This section shows a X.509 v3 certificate with encoded HITs. 420 Certificate: 421 Data: 422 Version: 3 (0x2) 423 Serial Number: 0 (0x0) 424 Signature Algorithm: sha1WithRSAEncryption 425 Issuer: CN=2001:1e:d709:1980:5c6a:bb0c:7650:a027 426 Validity 427 Not Before: Jun 22 13:39:32 2010 GMT 428 Not After : Jul 2 13:39:32 2010 GMT 429 Subject: CN=2001:1c:5a14:26de:a07c:385b:de35:60e3 430 Subject Public Key Info: 431 Public Key Algorithm: rsaEncryption 432 RSA Public Key: (1024 bit) 433 Modulus (1024 bit): 434 00:b9:5e:cc:d5:d9:7b:39:c2:42:3e:79:49:ad:7f: 435 0c:bd:0f:12:98:4e:b0:9d:ee:62:76:7a:7b:55:f0: 436 cc:a2:57:ac:b6:e2:6a:bc:1e:bd:cf:75:30:95:5b: 437 92:af:75:55:69:0b:c3:48:0f:b5:e4:15:30:79:89: 438 22:b3:fd:7e:51:59:d2:0d:d7:12:5d:44:f3:e8:05: 439 13:1f:5b:4f:89:fa:1e:6d:83:e9:e2:cf:bd:5c:6f: 440 ef:02:1e:c8:db:9a:48:9a:35:b8:b8:be:89:be:ab: 441 c8:dd:60:44:df:ac:01:b7:76:66:ab:5d:a1:a5:d0: 442 3c:8d:22:04:d4:24:59:60:0f 443 Exponent: 65537 (0x10001) 444 X509v3 extensions: 445 X509v3 Issuer Alternative Name: 446 IP Address:2001:1e:d709:1980:5c6a:bb0C:7650:a027 447 X509v3 Subject Alternative Name: 448 IP Address:2001:1c:5a14:26de:a07c:385b:de35:60e3 449 Signature Algorithm: sha1WithRSAEncryption 450 48:a1:25:fb:01:31:d9:80:76:1b:1a:2d:00:f1:26:22:3c:3b: 451 20:a0:cb:b2:28:d2:0c:21:d3:9e:3b:4a:ab:3d:f6:ea:ad:46: 452 f6:f5:c4:4f:71:ce:3e:7b:65:8d:58:75:2e:99:25:82:5f:73: 453 10:c6:c2:f0:4b:35:ff:5c:65:ac:fc:a4:a7:76:50:ab:62:50: 454 b8:86:21:e6:83:e1:c1:3d:20:c9:8e:13:ab:d7:4b:d4:ab:2d: 455 72:9d:f0:9f:5f:e0:6f:95:fa:a1:95:64:3f:74:63:e5:a8:1d: 456 f7:e6:48:98:33:53:7b:91:6d:b0:cb:af:32:15:8c:e0:01:a0: 457 a0:b8 459 Appendix C. Change log 461 Changes from version 00 to 01: 463 o Revised text on DN usage. 465 o Revised text on Cert group usage. 467 Changes from version 01 to 02: 469 o Revised the type numbers. 471 o Added a section on signaling. 473 Changes from version 02 to 03: 475 o Revised text on CERT usage in control packets. 477 Changes from version 03 to 04: 479 o Added the non-HIP aware use case to the Section 3. 481 o Clarified that the HITs are not always required in the 482 certificates. 484 o Rewrote the signaling section. 486 o LDAP URL to LDAP DN in Section 2 last paragraph. 488 o CERT is always covered by a signature as it's type number requires 490 o New example certificates 492 o Style and language clean-ups 494 o Changed IANA considerations 496 o Revised the type numbers 498 o RFC 2119 keywords 500 o Updated the IANA considerations section 502 o Rewrote the abstract 504 Changes from version 04 to 05: 506 o Clarified the examples in Section 3. 508 o Clarifications to Section Section 3. 510 o Modified the explanation of INVALID_CERTIFICATE to allow multiple 511 certs. 513 o Added reference to the IPv6 colon delimited presentation format. 515 o Small editorial changes. 517 Changes from version 05 to 06: 519 o Editorial changes. 521 o Unified the example in Section 3. 523 Changes from version 06 to 07: 525 o Editorial changes. 527 o Removed a the second paragraph in section 8. 529 o Changed the example in Appendix A (Cert created without the 530 leading zeroes in HITs). 532 Changes from version 07 to 08: 534 o Updated and checked the references. 536 Changes from version 08 to 09: 538 o Fixing boilerplate. 540 Changes from version 09 to 10: 542 o IANA considerations updated based on the IANA review. 544 o Updates based on the hip-chairs review. 546 o Updates based on the Gen-ART review. 548 Changes from version 10 to 11: 550 o Fixed the nits. 552 Authors' Addresses 554 Tobias Heer 555 Communication and Distributed Systems, RWTH Aachen University 556 Ahornstrasse 55 557 Aachen 558 Germany 560 Phone: +49 241 80 20 776 561 Email: heer@cs.rwth-aachen.de 562 URI: http://www.comsys.rwth-aachen.de/team/tobias-heer/ 564 Samu Varjonen 565 Helsinki Institute for Information Technology 566 Gustaf Haellstroemin katu 2b 567 Helsinki 568 Finland 570 Email: samu.varjonen@hiit.fi 571 URI: http://www.hiit.fi