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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Host Identity Protocol Heer 3 Internet-Draft Distributed Systems Group, RWTH 4 Intended status: Informational Aachen University 5 Expires: January 2, 2010 Varjonen 6 Helsinki Institute for Information 7 Technology 8 July 1, 2009 10 HIP Certificates 11 draft-ietf-hip-cert-01 13 Status of this Memo 15 This Internet-Draft is submitted to IETF in full conformance with the 16 provisions of BCP 78 and BCP 79. This document may not be modified, 17 and derivative works of it may not be created, except to format it 18 for publication as an RFC or to translate it into languages other 19 than English. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that 23 other groups may also distribute working documents as Internet- 24 Drafts. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 The list of current Internet-Drafts can be accessed at 32 http://www.ietf.org/ietf/1id-abstracts.txt. 34 The list of Internet-Draft Shadow Directories can be accessed at 35 http://www.ietf.org/shadow.html. 37 This Internet-Draft will expire on January 2, 2010. 39 Copyright Notice 41 Copyright (c) 2009 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents in effect on the date of 46 publication of this document (http://trustee.ietf.org/license-info). 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. 50 Abstract 52 This document specifies a certificate parameter called CERT for the 53 Host Identity Protocol (HIP). The CERT parameter is a container for 54 Simple Public Key Infrastructure (SPKI) and X.509.v3 certificates. 55 It is used for carrying these certificates in HIP control messages. 56 Additionally, this document specifies the representations of Host 57 Identity Tags in SPKI and X.509.v3 certificates. 59 Requirements Language 61 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 62 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 63 document are to be interpreted as described in RFC 2119 [RFC2119]. 65 1. Introduction 67 Digital certificates bind a piece of information to a public key by 68 means of a digital signature, and thus, enable the holder of a 69 private key to generate cryptographically verifiable statements. The 70 Host Identity Protocol (HIP)[RFC5201] defines a new cryptographic 71 namespace based on asymmetric cryptography. Each host's identity is 72 derived from a public key, allowing hosts to digitally sign data with 73 their private key. This document specifies the CERT parameter that 74 is used to transmit digital signatures in HIP. It corresponds to the 75 placeholder specified in Section 2 of [RFC5201]. 77 2. CERT Parameter 79 The CERT parameter is a container for a certain types of digital 80 certificates. It may either carry SPKI certificates or X.509.v3 81 certificates. It does not specify any certificate semantics. 82 However, it defines some organizational parameters that help HIP 83 hosts to transmit semantically grouped parameters in a more 84 systematic way. 86 The CERT parameter may be covered by the HIP SIGNATURE field and is a 87 non-critical parameter. 89 Each HIP packet may contain multiple CERT parameters. These 90 parameters may be related or unrelated. Related certificates are 91 managed in Cert groups. A cert group specifies a group of related 92 cert parameters that should be interpreted in a certain order (e.g. 93 for expressing certificate chains). For grouping Cert parameters, 94 the Cert group and the Cert count field must be set. Ungrouped 95 certificates exhibit a unique Cert group field and set the Cert count 96 to 1. CERT parameters with the same Cert group number in the group 97 field indicate a logical grouping. The Cert count field indicates 98 the number of CERT parameters in the group. 100 CERT parameters that belong to the same CERT group may be contained 101 in multiple sequential packets. This is indicated by a higher Cert 102 count than the amount of CERT parameters with matching Cert group 103 fields in a packet. Within a HIP packet, CERT parameters must be 104 placed in ascending order according to their Cert group field. Cert 105 groups may only span multiple packets if the Cert group does not fit 106 the packet. Only one Cert group may span two subsequent packets. 108 The Cert ID acts as a sequence number to identify the certificates in 109 a Cert group. The numbers in the Cert ID field must start from 1 up 110 to Cert count. 112 The CERT parameter can be used in R1, I2, R2, UPDATE and NOTIFY 113 messages. When CERT parameter is used in R1 message it is NOT 114 recommended to use grouping or hash and URL encodings. Initiator and 115 Responder can detect middleboxes on the path after R1 message is sent 116 by checking if control packets contain ECHO_REQUEST_M parameters as 117 defined in [HIP.middle_auth]. 119 0 1 2 3 120 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 1 121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 | Type | Length | 123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 | Cert group | Cert count | Cert ID | Cert type | 125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 126 | Certificate / 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 / | Padding | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 Type 768 132 Length Length in octets, excluding Type, Length, and Padding 133 Cert group Group ID grouping multiple related CERT parameters 134 Cert count Total count of certificates that are sent, possibly 135 in several consecutive HIP control packets. 136 Cert ID The sequence number for this certificate 137 Cert Type Describes the type of the certificate 138 Padding Any Padding, if necessary, to make the TLV a multiple 139 of 8 bytes. 141 The following certificate types are defined: 143 +--------------------------+-------------+ 144 | Cert format | Type number | 145 +--------------------------+-------------+ 146 | SPKI | 1 | 147 | X.509.v3 | 2 | 148 | Hash and URL of SPKI | 3 | 149 | Hash and URL of X.509.v3 | 4 | 150 +--------------------------+-------------+ 152 All implementations MUST support SPKI. The next section outlines the 153 use of HITs in SPKI. The SPKI and its formats are defined in 154 [RFC2693]. X.509.v3 certificates are defined in [RFC3280]. Wire 155 format for X.509.v3 is Distinguished Encoding Rules format as defined 156 in [X.690]. 158 Hash and URL encodings (3 and 4) are used as defined in [RFC4306]. 159 Using hash and URL encodings results in smaller HIP control packets, 160 but requires the receiver to resolve the URL or check local cache 161 against the hash. 163 It is not recommended to use hash and URL encodings when HIP-aware 164 middleboxes are present on the communication path between peers 165 because fetching remote certificates require the middlebox to buffer 166 the packets and to request remote data. This makes these devices 167 prone to denial of service (DoS) attacks. Moreover, middleboxes and 168 responders that request remote certificates can be used as deflectors 169 for distributed denial of service attacks. 171 3. SPKI Cert Object and Host Identities 173 When using SPKI certificates to transmit information related to HIP 174 hosts, HITs need to be enclosed within the certificates. In the 175 following we define the representation of those identifiers for SPKI 176 given as S-expressions. Note that the S-expressions are only the 177 human-readable representation of SPKI certificates. 179 As an example the Host Identity Tag of a host is expressed as 180 follows: 182 Format: (hash hit hit-of-host) 183 Example: (hash hit 2001:13:724d:f3c0:6ff0:33c2:15d8:5f50) 185 Appendix A shows a full example SPKI certificate with HIP content. 187 4. X.509.v3 Certificate Object and Host Identities 189 When using X.509.v3 certificates to transmit information related to 190 HIP hosts, HITs need to be enclosed within the certificates. HITs 191 are represented as issuer and subject alternative name X.509.v3 192 extensions as defined in [RFC2459]. Because the Distinguished Name 193 (DN) in X.509.v3 certificate cannot be empty HITs are also placed 194 into the Common Name (CN) in a colon delimited presentation format. 195 Placing CN is not necessary if DN contains any other information. It 196 is RECOMMENDED to use FQDN/NAI from the hosts HOST_ID parameter in DN 197 if one exists. 199 As an example the HIT of a host is expressed as follows: 201 Format: 202 Issuer: CN=hit-of-host 203 Subject: CN=hit-of-host 205 X509v3 extensions: 206 X509v3 Issuer Alternative Name: 207 IP Address:HIT-OF-HOST 208 X509v3 Subject Alternative Name: 209 IP Address:HIT-OF-HOST 211 Example: 212 Issuer: CN=2001:14:6cf:fae7:bb79:bf78:7d64:c056 213 Subject: CN=2001:14:6cf:fae7:bb79:bf78:7d64:c056 215 X509v3 extensions: 216 X509v3 Issuer Alternative Name: 217 IP Address:2001:14:6CF:FAE7:BB79:BF78:7D64:C056 218 X509v3 Subject Alternative Name: 219 IP Address:2001:14:6CF:FAE7:BB79:BF78:7D64:C056 221 Appendix B shows a full example X.509.v3 certificate with HIP 222 content. 224 5. Revocation of Certificates 226 Revocation of SPKI certificates is handled as defined in Section 5. 227 in [RFC2693] Revocation of X.509.v3 certificates is handled as 228 defined in Section 5 in [RFC2459]. 230 6. IANA Considerations 232 This document defines the CERT parameter for the Host Identity 233 Protocol [RFC5201]. This parameter is defined in Section 2 with type 234 768. The parameter type number is also defined in [RFC5201]. The 235 Cert Group and Cert ID namespaces are managed locally by each peer 236 that sends CERT parameters in HIP packets. 238 7. Security Considerations 240 Certificate grouping allows the certificates to be sent in multiple 241 consecutive packets. This might allow similar attacks as IP-layer 242 fragmentation allows, i.e. sending of fragments in wrong order and 243 skipping some fragments to delay or stall packet processing by the 244 victim in order to use resources (e.g. CPU or memory). 246 8. Acknowledgements 248 The authors would like to thank M. Komu and T. Henderson of fruitful 249 conversations on the subject. 251 9. References 253 9.1. Normative References 255 [HIP.middle_auth] 256 Heer, T., "End-Host Authentication for HIP Middleboxes", 257 . 259 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 260 Requirement Levels", BCP 14, RFC 2119, March 1997. 262 [RFC2459] Housley, R., Ford, W., Polk, T., and D. Solo, "Internet 263 X.509 Public Key Infrastructure Certificate and CRL 264 Profile", RFC 2459, January 1999. 266 [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, 267 B., and T. Ylonen, "SPKI Certificate Theory", RFC 2693, 268 September 1999. 270 [RFC3280] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet 271 X.509 Public Key Infrastructure Certificate and 272 Certificate Revocation List (CRL) Profile", RFC 3280, 273 April 2002. 275 [RFC4306] Kaufman, C., "Internet Key Exchange (IKEv2) Protocol", 276 RFC 4306, December 2005. 278 [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson, 279 "Host Identity Protocol", RFC 5201, April 2008. 281 9.2. Informative References 283 [X.690] ITU-T, "Recommendation X.690 Information Technology - 284 ASN.1 encoding rules: Specification of Basic Encoding 285 Rules (BER), Canonical Encoding Rules (CER) and 286 Distinguished Encoding Rules (DER)", July 2002, . 290 Appendix A. SPKI certificate example 292 This section shows a self-signed SPKI certificate of HIT 2001:14:6cf: 293 fae7:bb79:bf78:7d64:c056. The example has been indented for 294 readability. 296 (sequence 297 (public_key 298 (rsa-pkcs1-sha1 299 (e #010001#) 300 (n |n1CheoELqYRSkHYMQddub2TpILl+6H9wC/as6zFCZqOY43hsZgAjG0F 301 GoQwtyOyQjzO2Ykb2TmUCZemTYui/sR0zIbdwg1xafKl7ggZDkhk5an 302 PtGDxJxFalTYo6/A5ZQv8uatbaJgB/G7VM8G+O9HLucadad2zQUXpQf 303 gbK3S8=| 304 ) 305 ) 306 ) 307 (cert 308 (issuer 309 (hash hit 2001:0014:06cf:fae7:bb79:bf78:7d64:c056) 310 ) 311 (subject 312 (hash hit 2001:0014:06cf:fae7:bb79:bf78:7d64:c056) 313 ) 314 (not-before "2008-07-12_22:11:07") 315 (not-after "2008-07-22_22:11:07") 316 ) 317 (signature 318 (hash sha1 |kfElDhagiK0Bsqtj32Gq3t/1mxgA|) 319 |HiIqjjZIUzypvoxQyO0UovPm5uC4Xte0scEcBnENDIfn2DNy/bAtxGEdKq4O 320 dW80vTCmkF8/HXclgXLLVch3DxRNdSbYiiks000HpQt/OKqlTH+uUHBcHOAo 321 E42LmDskM9T5KQJoC/CH7871zfvojPnpkl2dUngOWv4q0r/wSJ0=| 322 ) 323 ) 325 Appendix B. X.509.v3 certificate example 327 This section shows a self-signed X.509.v3 certificate of HIT 2001:14: 328 6cf:fae7:bb79:bf78:7d64:c056. 330 Certificate: 331 Data: 332 Version: 3 (0x2) 333 Serial Number: 0 (0x0) 334 Signature Algorithm: sha1WithRSAEncryption 335 Issuer: CN=2001:14:6cf:fae7:bb79:bf78:7d64:c056 336 Validity 337 Not Before: Jul 12 18:58:38 2008 GMT 338 Not After : Jul 22 18:58:38 2008 GMT 339 Subject: CN=2001:14:6cf:fae7:bb79:bf78:7d64:c056 340 Subject Public Key Info: 341 Public Key Algorithm: rsaEncryption 342 RSA Public Key: (1024 bit) 343 Modulus (1024 bit): 344 00:9f:50:a1:7a:81:0b:a9:84:52:90:76:0c:41:d7: 345 6e:6f:64:e9:20:b9:7e:e8:7f:70:0b:f6:ac:eb:31: 346 42:66:a3:98:e3:78:6c:66:00:23:1b:41:46:a1:0c: 347 2d:c8:ec:90:8f:33:b6:62:46:f6:4e:65:02:65:e9: 348 93:62:e8:bf:b1:1d:33:21:b7:70:83:5c:5a:7c:a9: 349 7b:82:06:43:92:19:39:6a:73:ed:18:3c:49:c4:56: 350 a5:4d:8a:3a:fc:0e:59:42:ff:2e:6a:d6:da:26:00: 351 7f:1b:b5:4c:f0:6f:8e:f4:72:ee:71:a7:5a:77:6c: 352 d0:51:7a:50:7e:06:ca:dd:2f 353 Exponent: 65537 (0x10001) 354 X509v3 extensions: 355 X509v3 Basic Constraints: 356 CA:TRUE 357 X509v3 Issuer Alternative Name: 358 IP Address:2001:14:6CF:FAE7:BB79:BF78:7D64:C056 359 X509v3 Subject Alternative Name: 360 IP Address:2001:14:6CF:FAE7:BB79:BF78:7D64:C056 361 Signature Algorithm: sha1WithRSAEncryption 362 19:32:0b:72:a8:6c:f9:65:20:5b:1d:9a:e1:c7:39:97:c7:8a: 363 4d:d1:01:f9:7d:0b:0d:6f:61:a2:e3:2c:62:30:28:f6:36:db: 364 62:bc:7f:d1:9b:6d:cc:da:e3:9b:90:e7:53:9e:55:28:51:7e: 365 39:de:23:24:f5:a9:97:7a:ba:ce:54:3e:cf:8b:68:04:f6:be: 366 78:94:9f:d3:20:62:96:14:84:51:af:c7:ba:30:ae:b1:d6:7e: 367 7f:32:42:9c:f6:f5:76:27:0a:28:58:8b:b5:85:e7:e9:5a:ff: 368 aa:4c:57:55:95:09:33:ac:0b:8c:fd:05:4a:5e:60:e7:7f:d7: 369 42:f0 371 Appendix C. Change log 373 Changes from version 00 to 01: 375 o Revised text about DN usage. 377 o Revised text about Cert group usage. 379 Authors' Addresses 381 Tobias Heer 382 Distributed Systems Group, RWTH Aachen University 383 Ahornstrasse 55 384 Aachen 385 Germany 387 Phone: +49 241 80 214 36 388 Email: heer@cs.rwth-aachen.de 389 URI: http://ds.cs.rwth-aachen.de/members/heer 391 Samu Varjonen 392 Helsinki Institute for Information Technology 393 Metsnneidonkuja 4 394 Helsinki 395 Finland 397 Fax: +35896949768 398 Email: samu.varjonen@hiit.fi 399 URI: http://www.hiit.fi