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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 informational reference (is this intentional?): RFC 6253 (Obsoleted by RFC 8002) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Host Identity Protocol Heer 3 Internet-Draft Albstadt-Sigmaringen University 4 Obsoletes: 6253 (if approved) Varjonen 5 Updates: 7401 (if approved) University of Helsinki 6 Intended status: Standards Track December 9, 2015 7 Expires: June 11, 2016 9 Host Identity Protocol Certificates 10 draft-ietf-hip-rfc6253-bis-06 12 Abstract 14 The Certificate (CERT) parameter is a container for digital 15 certificates. It is used for carrying these certificates in Host 16 Identity Protocol (HIP) control packets. This document specifies the 17 certificate parameter and the error signaling in case of a failed 18 verification. Additionally, this document specifies the 19 representations of Host Identity Tags in X.509 version 3 (v3). 21 The concrete use cases of certificates, including how certificates 22 are obtained, requested, and which actions are taken upon successful 23 or failed verification, are specific to the scenario in which the 24 certificates are used. Hence, the definition of these scenario- 25 specific aspects is left to the documents that use the CERT 26 parameter. 28 This document updates RFC7401 and obsoletes RFC6253. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on June 11, 2016. 47 Copyright Notice 48 Copyright (c) 2015 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 1. Introduction 63 Digital certificates bind pieces of information to a public key by 64 means of a digital signature, and thus, enable the holder of a 65 private key to generate cryptographically verifiable statements. The 66 Host Identity Protocol (HIP) [RFC7401] defines a new cryptographic 67 namespace based on asymmetric cryptography. The identity of each 68 host is derived from a public key, allowing hosts to digitally sign 69 data and issue certificates with their private key. This document 70 specifies the CERT parameter, which is used to transmit digital 71 certificates in HIP. It fills the placeholder specified in 72 Section 5.2 of [RFC7401], and thus, updates [RFC7401]. 74 1.1. Requirements Language 76 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 77 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 78 "OPTIONAL" in this document are to be interpreted as described in RFC 79 2119 [RFC2119]. 81 2. CERT Parameter 83 The CERT parameter is a container for certain types of digital 84 certificates. It does not specify any certificate semantics. 85 However, it defines supplementary parameters that help HIP hosts to 86 transmit semantically grouped CERT parameters in a more systematic 87 way. The specific use of the CERT parameter for different use cases 88 is intentionally not discussed in this document. Hence, the use of 89 the CERT parameter will be defined in the documents that use the CERT 90 parameter. 92 The CERT parameter is covered and protected, when present, by the HIP 93 SIGNATURE field and is a non-critical parameter. 95 The CERT parameter can be used in all HIP packets. However, using it 96 in the first Initiator (I1) packet is NOT RECOMMENDED because it can 97 increase the processing times of I1s, which can be problematic when 98 processing storms of I1s. Each HIP control packet MAY contain 99 multiple CERT parameters. These parameters MAY be related or 100 unrelated. Related certificates are managed in Cert groups. A Cert 101 group specifies a group of related CERT parameters that SHOULD be 102 interpreted in a certain order (e.g., for expressing certificate 103 chains). Ungrouped certificates exhibit a unique Cert group field 104 and set the Cert count to 1. CERT parameters with the same Cert 105 group number in the group field indicate a logical grouping. The 106 Cert count field indicates the number of CERT parameters in the 107 group. 109 CERT parameters that belong to the same Cert group MAY be contained 110 in multiple sequential HIP control packets. This is indicated by a 111 higher Cert count than the amount of CERT parameters with matching 112 Cert group fields in a HIP control packet. The CERT parameters MUST 113 be placed in ascending order, within a HIP control packet, according 114 to their Cert group field. Cert groups MAY only span multiple 115 packets if the Cert group does not fit the packet. A HIP packet MUST 116 NOT contain more than one incomplete Cert group that continues in the 117 next HIP control packet. 119 The Cert ID acts as a sequence number to identify the certificates in 120 a Cert group. The numbers in the Cert ID field MUST start from 1 up 121 to Cert count. 123 The Cert Group and Cert ID namespaces are managed locally by each 124 host that sends CERT parameters in HIP control packets. 126 0 1 2 3 127 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 1 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 | Type | Length | 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 | Cert group | Cert count | Cert ID | Cert type | 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Certificate / 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 / | Padding (variable length) | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 Type 768 139 Length Length in octets, excluding Type, Length, and Padding 140 Cert group Group ID grouping multiple related CERT parameters 141 Cert count Total count of certificates that are sent, possibly 142 in several consecutive HIP control packets. 144 Cert ID The sequence number for this certificate 145 Cert Type Indicates the type of the certificate 146 Padding Any Padding, if necessary, to make the TLV a multiple 147 of 8 bytes. 149 The certificates MUST use the algorithms defined in [RFC7401] as the 150 signature and hash algorithms. 152 The following certificate types are defined: 154 +--------------------------------+-------------+ 155 | Cert format | Type number | 156 +--------------------------------+-------------+ 157 | Reserved | 0 | 158 | X.509 v3 | 1 | 159 | Hash and URL of X.509 v3 | 2 | 160 | LDAP URL of X.509 v3 | 3 | 161 | Distinguished Name of X.509 v3 | 4 | 162 +--------------------------------+-------------+ 164 The next sections outline the use of Host Identity Tags (HITs) in 165 X.509 v3. X.509 v3 certificates and the handling procedures are 166 defined in [RFC5280]. The wire format for X.509 v3 is the 167 Distinguished Encoding Rules format as defined in [X.690]. 169 Hash and Uniform Resource Locator (URL) encodings (3 and 4) are used 170 as defined in Section 3.6 of [RFC7296]. Using hash and URL encodings 171 results in smaller HIP control packets than by including the 172 certificate(s), but requires the receiver to resolve the URL or check 173 a local cache against the hash. 175 Lightweight Directory Access Protocol (LDAP) URL encodings (5 and 6) 176 are used as defined in [RFC4516]. Using LDAP URL encoding results in 177 smaller HIP control packets but requires the receiver to retrieve the 178 certificate or check a local cache against the URL. 180 Distinguished Name (DN) encodings (7 and 8) are represented by the 181 string representation of the certificate's subject DN as defined in 182 [RFC4514]. Using the DN encoding results in smaller HIP control 183 packets, but requires the receiver to retrieve the certificate or 184 check a local cache against the DN. 186 3. X.509 v3 Certificate Object and Host Identities 188 If needed, HITs can represent an issuer, a subject, or both in X.509 189 v3. HITs are represented as IPv6 addresses as defined in [RFC7343]. 190 When the Host Identifier (HI) is used to sign the certificate, the 191 respective HIT SHOULD be placed into the Issuer Alternative Name 192 (IAN) extension using the GeneralName form iPAddress as defined in 193 [RFC5280]. When the certificate is issued for a HIP host, identified 194 by a HIT and HI, the respective HIT SHOULD be placed into the Subject 195 Alternative Name (SAN) extension using the GeneralName form 196 iPAddress, and the full HI is presented as the subject's public key 197 info as defined in [RFC5280]. 199 The following examples illustrate how HITs are presented as issuer 200 and subject in the X.509 v3 extension alternative names. 202 Format of X509v3 extensions: 203 X509v3 Issuer Alternative Name: 204 IP Address:hit-of-issuer 205 X509v3 Subject Alternative Name: 206 IP Address:hit-of-subject 208 Example X509v3 extensions: 209 X509v3 Issuer Alternative Name: 210 IP Address:2001:24:6cf:fae7:bb79:bf78:7d64:c056 211 X509v3 Subject Alternative Name: 212 IP Address:2001:2c:5a14:26de:a07c:385b:de35:60e3 214 Appendix A shows a full example X.509 v3 certificate with HIP 215 content. 217 As another example, consider a managed Public Key Infrastructure 218 (PKI) environment in which the peers have certificates that are 219 anchored in (potentially different) managed trust chains. In this 220 scenario, the certificates issued to HIP hosts are signed by 221 intermediate Certification Authorities (CAs) up to a root CA. In 222 this example, the managed PKI environment is neither HIP aware, nor 223 can it be configured to compute HITs and include them in the 224 certificates. 226 When HIP communications are established, the HIP hosts not only need 227 to send their identity certificates (or pointers to their 228 certificates), but also the chain of intermediate CAs (or pointers to 229 the CAs) up to the root CA, or to a CA that is trusted by the remote 230 peer. This chain of certificates SHOULD be sent in a Cert group as 231 specified in Section 2. The HIP peers validate each other's 232 certificates and compute peer HITs based on the certificate public 233 keys. 235 4. Revocation of Certificates 237 Revocation of X.509 v3 certificates is handled as defined in 238 Section 5 of [RFC5280]. 240 5. Error Signaling 242 If the Initiator does not send the certificate that the Responder 243 requires, the Responder may take actions (e.g. reject the 244 connection). The Responder MAY signal this to the Initiator by 245 sending a HIP NOTIFY message with NOTIFICATION parameter error type 246 CREDENTIALS_REQUIRED. 248 If the verification of a certificate fails, a verifier MAY signal 249 this to the provider of the certificate by sending a HIP NOTIFY 250 message with NOTIFICATION parameter error type INVALID_CERTIFICATE. 252 NOTIFICATION PARAMETER - ERROR TYPES Value 253 ------------------------------------ ----- 255 CREDENTIALS_REQUIRED 48 257 The Responder is unwilling to set up an association, 258 as the Initiator did not send the needed credentials. 260 INVALID_CERTIFICATE 50 262 Sent in response to a failed verification of a certificate. 263 Notification Data MAY contain n (n calculated from the 264 NOTIFICATION parameter length) groups of Cert group and 265 Cert ID octets (in this order) of the CERT parameter that 266 caused the failure. 268 6. IANA Considerations 270 As this document obsoletes [RFC6253], references to [RFC6253] in IANA 271 registries have to be replaced by references to this document. This 272 document changes Certificate type registry in Section 2. 274 7. Security Considerations 275 Certificate grouping allows the certificates to be sent in multiple 276 consecutive packets. This might allow similar attacks, as IP-layer 277 fragmentation allows, for example, the sending of fragments in the 278 wrong order and skipping some fragments to delay or stall packet 279 processing by the victim in order to use resources (e.g., CPU or 280 memory). Hence, hosts SHOULD implement mechanisms to discard 281 certificate groups with outstanding certificates if state space is 282 scarce. 284 Although, CERT parameter is allowed in the first Initiator (I1) 285 packet it is NOT RECOMMENDED because it can increase the processing 286 times of I1s, which can be problematic when processing storms of I1s. 287 Furthermore, Initiator has to take into consideration that the 288 Responder can drop the CERT parameter in I1 without processing the 289 parameter. 291 Checking of the URL and LDAP entries might allow denial-of-service 292 (DoS) attacks, where the target host may be subjected to bogus work. 294 Security considerations for X.509 v3 are discussed in [RFC5280]. 296 8. Acknowledgements 298 The authors would like to thank A. Keranen, D. Mattes, M. Komu and T. 299 Henderson for the fruitful conversations on the subject. D. Mattes 300 most notably contributed the non-HIP aware use case in Section 3. 302 9. References 304 9.1. Normative References 306 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 307 Requirement Levels", BCP 14, RFC 2119, March 1997. 309 [RFC4514] Zeilenga, K., "Lightweight Directory Access Protocol 310 (LDAP): String Representation of Distinguished Names", RFC 311 4514, June 2006. 313 [RFC4516] Smith, M. and T. Howes, "Lightweight Directory Access 314 Protocol (LDAP): Uniform Resource Locator", RFC 4516, June 315 2006. 317 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 318 Housley, R., and W. Polk, "Internet X.509 Public Key 319 Infrastructure Certificate and Certificate Revocation List 320 (CRL) Profile", RFC 5280, May 2008. 322 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 323 Kivinen, "Internet Key Exchange Protocol Version 2 324 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 325 2014, . 327 [RFC7343] Laganier, J. and F. Dupont, "An IPv6 Prefix for Overlay 328 Routable Cryptographic Hash Identifiers Version 2 329 (ORCHIDv2)", RFC 7343, DOI 10.17487/RFC7343, September 330 2014, . 332 [RFC7401] Moskowitz, R., Heer, T., Jokela, P., and T. Henderson, 333 "Host Identity Protocol Version 2 (HIPv2)", RFC 7401, 334 April 2015. 336 [X.690] ITU-T, , "Recommendation X.690 (2002) | ISO/IEC 337 8825-1:2002, Information Technology - ASN.1 encoding 338 rules: Specification of Basic Encoding Rules (BER), 339 Canonical Encoding Rules (CER) and Distinguished Encoding 340 Rules (DER)", July 2002. 342 9.2. Informative References 344 [RFC6253] Heer, T. and S. Varjonen, "Host Identity Protocol 345 Certificates", RFC 6253, DOI 10.17487/RFC6253, May 2011, 346 . 348 Appendix A. X.509 v3 certificate example 350 This section shows a X.509 v3 certificate with encoded HITs. 352 Certificate: 353 Data: 354 Version: 3 (0x2) 355 Serial Number: 0 (0x0) 356 Signature Algorithm: sha1WithRSAEncryption 357 Issuer: CN=Example issuing host, DC=example, DC=com 358 Validity 359 Not Before: Mar 11 09:01:39 2011 GMT 360 Not After : Mar 21 09:01:39 2011 GMT 361 Subject: CN=Example subject host, DC=example, DC=com 362 Subject Public Key Info: 363 Public Key Algorithm: rsaEncryption 364 RSA Public Key: (1024 bit) 365 Modulus (1024 bit): 366 00:c0:db:38:50:8e:63:ed:96:ea:c6:c4:ec:a3:36: 367 62:e2:28:e9:74:9c:f5:2f:cb:58:0e:52:54:60:b5: 368 fa:98:87:0d:22:ab:d8:6a:61:74:a9:ee:0b:ae:cd: 369 18:6f:05:ab:69:66:42:46:00:a2:c0:0c:3a:28:67: 371 09:cc:52:27:da:79:3e:67:d7:d8:d0:7c:f1:a1:26: 372 fa:38:8f:73:f5:b0:20:c6:f2:0b:7d:77:43:aa:c7: 373 98:91:7e:1e:04:31:0d:ca:94:55:20:c4:4f:ba:b1: 374 df:d4:61:9d:dd:b9:b5:47:94:6c:06:91:69:30:42: 375 9c:0a:8b:e3:00:ce:49:ab:e3 376 Exponent: 65537 (0x10001) 377 X509v3 extensions: 378 X509v3 Issuer Alternative Name: 379 IP Address:2001:23:8d83:41c5:dc9f:38ed:e742:7281 380 X509v3 Subject Alternative Name: 381 IP Address:2001:2c:6e02:d3e0:9b90:8417:673e:99db 382 Signature Algorithm: sha1WithRSAEncryption 383 83:68:b4:38:63:a6:ae:57:68:e2:4d:73:5d:8f:11:e4:ba:30: 384 a0:19:ca:86:22:e9:6b:e9:36:96:af:95:bd:e8:02:b9:72:2f: 385 30:a2:62:ac:b2:fa:3d:25:c5:24:fd:8d:32:aa:01:4f:a5:8a: 386 f5:06:52:56:0a:86:55:39:2b:ee:7a:7b:46:14:d7:5d:15:82: 387 4d:74:06:ca:b7:8c:54:c1:6b:33:7f:77:82:d8:95:e1:05:ca: 388 e2:0d:22:1d:86:fc:1c:c4:a4:cf:c6:bc:ab:ec:b8:2a:1e:4b: 389 04:7e:49:9c:8f:9d:98:58:9c:63:c5:97:b5:41:94:f7:ef:93: 390 57:29 392 Appendix B. Change log 394 Contents of draft-ietf-hip-rfc6253-bis-00: 396 o RFC6253 was submitted as draft-RFC. 398 Changes from version 01 to 02: 400 o Updated the references. 402 Changes from version 02 to 03: 404 o Fixed the nits raised by the working group. 406 Changes from version 03 to 04: 408 o Added "obsoletes RFC 6253". 410 Changes from version 04 to 05: 412 o Updates to contact details. 414 o Correct updates and obsoletes headers. 416 o Removed the pre5378 disclaimer. 418 o Updated references. 420 o Removed the SPKI references from the document. 422 Changes from version 05 to 06: 424 o Addressed the Int-Dir review comments from Korhonen. 426 Authors' Addresses 428 Tobias Heer 429 Albstadt-Sigmaringen University 430 Poststr. 6 431 72458 Albstadt 432 Germany 434 Email: heer@hs-albsig.de 436 Samu Varjonen 437 University of Helsinki 438 Gustaf Haellstroemin katu 2b 439 Helsinki 440 Finland 442 Email: samu.varjonen@helsinki.fi