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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 15, 2011 Helsinki Institute for Information 7 Technology 8 March 14, 2011 10 Host Identity Protocol Certificates 11 draft-ietf-hip-cert-12 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 15, 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 than by including the 192 certificate(s), but requires the receiver to resolve the URL or check 193 a local cache against the hash. 195 LDAP URL encodings (5 and 6) are used as defined in [RFC4516]. Using 196 LDAP URL encoding results in smaller HIP control packets but requires 197 the receiver to retrieve the certificate or check a local cache 198 against the URL. 200 Distinguished name (DN) encodings (7 and 8) are represented by the 201 string representation of the certificate's subject DN as defined in 202 [RFC4514]. Using the DN encoding results in smaller HIP control 203 packets, but requires the receiver to retrieve the certificate or 204 check a local cache against the DN. 206 3. X.509 v3 Certificate Object and Host Identities 208 If needed, HITs can represent an issuer, a subject, or both in x.509 209 v3. HITs are represented as IPv6 addresses as defined in [RFC4843]. 210 When Host Identifier ( HI ) is used to sign the certificate the 211 respective HIT MUST be placed in to the Issuer Alternative Name (IAN) 212 extension using the GeneralName form iPAddress as defined in 213 [RFC5280]. When the certificate is issued for a HIP host, identified 214 by a HIT and HI, the respective HIT MUST be placed in to the Subject 215 Alternative Name (SAN) extension using the GeneralName form iPAddress 216 and the full HI is presented as the subjects public key info as 217 defined in [RFC5280]. 219 The following examples illustrate how HITs are presented as issuer 220 and subject in the X.509 v3 extension alternative names. 222 Format of X509v3 extensions: 223 X509v3 Issuer Alternative Name: 224 IP Address:hit-of-issuer 225 X509v3 Subject Alternative Name: 226 IP Address:hit-of-subject 228 Example X509v3 extensions: 229 X509v3 Issuer Alternative Name: 230 IP Address:2001:14:6cf:fae7:bb79:bf78:7d64:c056 231 X509v3 Subject Alternative Name: 232 IP Address:2001:1C:5a14:26de:a07C:385b:de35:60e3 234 Appendix B shows a full example X.509 v3 certificate with HIP 235 content. 237 As another example, consider a managed Public Key Infrastructure 238 (PKI) environment in which the peers have certificates that are 239 anchored in (potentially different) managed trust chains. In this 240 scenario, the certificates issued to HIP hosts are signed by 241 intermediate Certification Authorities (CAs) up to a root CA. In 242 this example, the managed PKI environment is neither HIP aware, nor 243 can it be configured to compute HITs and include them in the 244 certificates. 246 When HIP communications are established, the HIP hosts not only need 247 to send their identity certificates (or pointers to their 248 certificates), but also the chain of intermediate CAs (or pointers to 249 the CAs) up to the root CA, or to a CA that is trusted by the remote 250 peer. This chain of certificates MUST be sent in a Cert group as 251 specified in Section 2. The HIP peers validate each other's 252 certificates and compute peer HITs based on the certificate public 253 keys. 255 4. SPKI Cert Object and Host Identities 257 When using SPKI certificates to transmit information related to HIP 258 hosts, HITs need to be enclosed within the certificates. HITs can 259 represent an issuer, a subject, or both. In the following we define 260 the representation of those identifiers for SPKI given as 261 S-expressions. Note that the S-expressions are only the human- 262 readable representation of SPKI certificates. Full HIs are presented 263 in the public key sequences of SPKI certificates. 265 As an example the Host Identity Tag of a host is expressed as 266 follows: 268 Format: (hash hit hit-of-host) 269 Example: (hash hit 2001:13:724d:f3c0:6ff0:33c2:15d8:5f50) 271 Appendix A shows a full example SPKI certificate with HIP content. 273 5. Revocation of Certificates 275 Revocation of X.509 v3 certificates is handled as defined in Section 276 5 of [RFC5280]. Revocation of SPKI certificates is handled as 277 defined in Section 5 of [RFC2693]. 279 6. Error signaling 281 If the Initiator does not send the certificate that the Responder 282 requires the Responder may take actions (e.g. reject the connection). 283 The Responder MAY signal this to the Initiator by sending a HIP 284 NOTIFY message with NOTIFICATION parameter error type 285 CREDENTIALS_NEEDED. 287 If the verification of a certificate fails, a verifier MAY signal 288 this to the provider of the certificate by sending a HIP NOTIFY 289 message with NOTIFICATION parameter error type INVALID_CERTIFICATE. 291 NOTIFICATION PARAMETER - ERROR TYPES Value 292 ------------------------------------ ----- 294 CREDENTIALS_REQUIRED 48 296 The Responder is unwilling to set up an association 297 as the Initiator did not send the needed credentials. 299 INVALID_CERTIFICATE 50 301 Sent in response to a failed verification of a certificate. 302 Notification Data MAY contain n groups of 2 octets (n calculated 303 from the NOTIFICATION parameter length), in order Cert group and 304 Cert ID of the certificate parameter that caused the failure. 306 7. IANA Considerations 308 This document defines the CERT parameter for the Host Identity 309 Protocol [RFC5201]. This parameter is defined in Section 2 with type 310 768. The parameter type number is also defined in [RFC5201]. 312 The CERT parameter has 8-bit unsigned integer field for different 313 certificate types, for which IANA is to create and maintain a new 314 sub-registry entitled "HIP certificate types" under the "Host 315 Identity Protocol (HIP) Parameters". Initial values for the 316 Certificate type registry are given in Section 2. New values for the 317 Certificate types from the unassigned space are assigned through IETF 318 Review. 320 In Section 6 this document defines two new types for "NOTIFY message 321 types" sub-registry under "Host Identity Protocol (HIP) Parameters". 323 8. Security Considerations 325 Certificate grouping allows the certificates to be sent in multiple 326 consecutive packets. This might allow similar attacks as IP-layer 327 fragmentation allows, for example sending of fragments in wrong order 328 and skipping some fragments to delay or stall packet processing by 329 the victim in order to use resources (e.g. CPU or memory). Hence, 330 hosts SHOULD implement mechanisms to discard certificate groups with 331 outstanding certificates if state space is scarce. 333 Checking of the URL and LDAP entries might allow DoS attacks, where 334 the target host may be subjected to bogus work. 336 Security considerations for SPKI certificates are discussed in 337 [RFC2693] and for X.509 v3 in [RFC5280] 339 9. Acknowledgements 341 The authors would like to thank A. Keranen, D. Mattes, M. Komu and T. 342 Henderson for the fruitful conversations on the subject. D. Mattes 343 most notably contributed the non-HIP aware use case in Section 3. 345 10. Normative References 347 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 348 Requirement Levels", BCP 14, RFC 2119, March 1997. 350 [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, 351 B., and T. Ylonen, "SPKI Certificate Theory", RFC 2693, 352 September 1999. 354 [RFC4514] Zeilenga, K., "Lightweight Directory Access Protocol 355 (LDAP): String Representation of Distinguished Names", 356 RFC 4514, June 2006. 358 [RFC4516] Smith, M. and T. Howes, "Lightweight Directory Access 359 Protocol (LDAP): Uniform Resource Locator", RFC 4516, 360 June 2006. 362 [RFC4843] Nikander, P., Laganier, J., and F. Dupont, "An IPv6 Prefix 363 for Overlay Routable Cryptographic Hash Identifiers 364 (ORCHID)", RFC 4843, April 2007. 366 [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, 367 "Host Identity Protocol", RFC 5201, April 2008. 369 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 370 Housley, R., and W. Polk, "Internet X.509 Public Key 371 Infrastructure Certificate and Certificate Revocation List 372 (CRL) Profile", RFC 5280, May 2008. 374 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 375 "Internet Key Exchange Protocol Version 2 (IKEv2)", 376 RFC 5996, September 2010. 378 [X.690] ITU-T, "Recommendation X.690 (2002) | ISO/IEC 8825-1:2002, 379 Information Technology - ASN.1 encoding rules: 380 Specification of Basic Encoding Rules (BER), Canonical 381 Encoding Rules (CER) and Distinguished Encoding Rules 382 (DER)", July 2002. 384 Appendix A. SPKI certificate example 386 This section shows a SPKI certificate with encoded HITs. The example 387 has been indented for readability. 389 (sequence 390 (public_key 391 (rsa-pkcs1-sha1 392 (e #010001#) 393 (n |yDwznOwX0w+zvQbpWoTnfWrUPLKW2NFrpXbsIcH/QBSLb 394 k1RKTZhLasFwvtSHAjqh220W8gRiQAGIqKplyrDEqSrJp 395 OdIsHIQ8BQhJAyILWA1Sa6f5wAnWozDfgdXoKLNdT8ZNB 396 mzluPiw4ozc78p6MHElH75Hm3yHaWxT+s83M=| 397 ) 398 ) 399 ) 400 (cert 401 (issuer 402 (hash hit 2001:15:2453:698a:9aa:253a:dcb5:981e) 403 ) 404 (subject 405 (hash hit 2001:12:ccd6:4715:72a3:2ab1:77e4:4acc) 406 ) 407 (not-before "2011-01-12_13:43:09") 408 (not-after "2011-01-22_13:43:09") 409 ) 410 (signature 411 (hash sha1 |h5fC8HUMATTtK0cjYqIgeN3HCIMA|) 412 |u8NTRutINI/AeeZgN6bngjvjYPtVahvY7MhGfenTpT7MCgBy 413 NoZglqH5Cy2vH6LrQFYWx0MjWoYwHKimEuBKCNd4TK6hrCyAI 414 CIDJAZ70TyKXgONwDNWPOmcc3lFmsih8ezkoBseFWHqRGISIm 415 MLdeaMciP4lVfxPY2AQKdMrBc=| 416 ) 417 ) 419 Appendix B. X.509.v3 certificate example 421 This section shows a X.509 v3 certificate with encoded HITs. 423 Certificate: 424 Data: 425 Version: 3 (0x2) 426 Serial Number: 0 (0x0) 427 Signature Algorithm: sha1WithRSAEncryption 428 Issuer: CN=Example issuing host, DC=example, DC=com 429 Validity 430 Not Before: Mar 11 09:01:39 2011 GMT 431 Not After : Mar 21 09:01:39 2011 GMT 432 Subject: CN=Example subject host, DC=example, DC=com 433 Subject Public Key Info: 434 Public Key Algorithm: rsaEncryption 435 RSA Public Key: (1024 bit) 436 Modulus (1024 bit): 437 00:c0:db:38:50:8e:63:ed:96:ea:c6:c4:ec:a3:36: 438 62:e2:28:e9:74:9c:f5:2f:cb:58:0e:52:54:60:b5: 439 fa:98:87:0d:22:ab:d8:6a:61:74:a9:ee:0b:ae:cd: 440 18:6f:05:ab:69:66:42:46:00:a2:c0:0c:3a:28:67: 441 09:cc:52:27:da:79:3e:67:d7:d8:d0:7c:f1:a1:26: 442 fa:38:8f:73:f5:b0:20:c6:f2:0b:7d:77:43:aa:c7: 443 98:91:7e:1e:04:31:0d:ca:94:55:20:c4:4f:ba:b1: 444 df:d4:61:9d:dd:b9:b5:47:94:6c:06:91:69:30:42: 445 9c:0a:8b:e3:00:ce:49:ab:e3 446 Exponent: 65537 (0x10001) 447 X509v3 extensions: 448 X509v3 Issuer Alternative Name: 449 IP Address:2001:13:8D83:41C5:DC9F:38ED:E742:7281 450 X509v3 Subject Alternative Name: 451 IP Address:2001:1C:6E02:D3E0:9B90:8417:673E:99DB 452 Signature Algorithm: sha1WithRSAEncryption 453 83:68:b4:38:63:a6:ae:57:68:e2:4d:73:5d:8f:11:e4:ba:30: 454 a0:19:ca:86:22:e9:6b:e9:36:96:af:95:bd:e8:02:b9:72:2f: 455 30:a2:62:ac:b2:fa:3d:25:c5:24:fd:8d:32:aa:01:4f:a5:8a: 456 f5:06:52:56:0a:86:55:39:2b:ee:7a:7b:46:14:d7:5d:15:82: 457 4d:74:06:ca:b7:8c:54:c1:6b:33:7f:77:82:d8:95:e1:05:ca: 458 e2:0d:22:1d:86:fc:1c:c4:a4:cf:c6:bc:ab:ec:b8:2a:1e:4b: 459 04:7e:49:9c:8f:9d:98:58:9c:63:c5:97:b5:41:94:f7:ef:93: 460 57:29 462 Appendix C. Change log 464 Changes from version 00 to 01: 466 o Revised text on DN usage. 468 o Revised text on Cert group usage. 470 Changes from version 01 to 02: 472 o Revised the type numbers. 474 o Added a section on signaling. 476 Changes from version 02 to 03: 478 o Revised text on CERT usage in control packets. 480 Changes from version 03 to 04: 482 o Added the non-HIP aware use case to the Section 3. 484 o Clarified that the HITs are not always required in the 485 certificates. 487 o Rewrote the signaling section. 489 o LDAP URL to LDAP DN in Section 2 last paragraph. 491 o CERT is always covered by a signature as it's type number requires 493 o New example certificates 495 o Style and language clean-ups 497 o Changed IANA considerations 499 o Revised the type numbers 501 o RFC 2119 keywords 503 o Updated the IANA considerations section 505 o Rewrote the abstract 507 Changes from version 04 to 05: 509 o Clarified the examples in Section 3. 511 o Clarifications to Section Section 3. 513 o Modified the explanation of INVALID_CERTIFICATE to allow multiple 514 certs. 516 o Added reference to the IPv6 colon delimited presentation format. 518 o Small editorial changes. 520 Changes from version 05 to 06: 522 o Editorial changes. 524 o Unified the example in Section 3. 526 Changes from version 06 to 07: 528 o Editorial changes. 530 o Removed a the second paragraph in section 8. 532 o Changed the example in Appendix A (Cert created without the 533 leading zeroes in HITs). 535 Changes from version 07 to 08: 537 o Updated and checked the references. 539 Changes from version 08 to 09: 541 o Fixing boilerplate. 543 Changes from version 09 to 10: 545 o IANA considerations updated based on the IANA review. 547 o Updates based on the hip-chairs review. 549 o Updates based on the Gen-ART review. 551 Changes from version 10 to 11: 553 o Fixed the nits. 555 Changes from version 11 to 12: 557 o Updates based on the PKIX WG review. 559 Authors' Addresses 561 Tobias Heer 562 Communication and Distributed Systems, RWTH Aachen University 563 Ahornstrasse 55 564 Aachen 565 Germany 567 Phone: +49 241 80 20 776 568 Email: heer@cs.rwth-aachen.de 569 URI: http://www.comsys.rwth-aachen.de/team/tobias-heer/ 571 Samu Varjonen 572 Helsinki Institute for Information Technology 573 Gustaf Haellstroemin katu 2b 574 Helsinki 575 Finland 577 Email: samu.varjonen@hiit.fi 578 URI: http://www.hiit.fi