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Barnes 5 Expires: April 20, 2019 iconectiv 6 October 17, 2018 8 PASSporT SHAKEN Extension (SHAKEN) 9 draft-ietf-stir-passport-shaken-04 11 Abstract 13 This document extends PASSporT, which is a token object that conveys 14 cryptographically-signed information about the participants involved 15 in communications, to include information defined as part of the 16 SHAKEN specification from ATIS (Alliance for Telecommunications 17 Industry Solutions) and the SIP Forum IP-NNI Joint Task Force. These 18 extensions provide a level of confidence in the correctness of the 19 originating identity for a telephone network that has communications 20 coming from both STIR participating originating communications as 21 well as communications that does not include STIR information. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on April 20, 2019. 40 Copyright Notice 42 Copyright (c) 2018 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 59 3. Overview of 'shaken' PASSporT extension . . . . . . . . . . . 3 60 4. PASSporT 'attest' Claim . . . . . . . . . . . . . . . . . . . 3 61 5. PASSporT 'origid' Claim . . . . . . . . . . . . . . . . . . . 4 62 6. Example "shaken" PASSporT . . . . . . . . . . . . . . . . . . 4 63 7. Using 'shaken' in SIP . . . . . . . . . . . . . . . . . . . . 5 64 8. Order of Claim Keys . . . . . . . . . . . . . . . . . . . . . 5 65 9. Security Considerations . . . . . . . . . . . . . . . . . . . 5 66 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 67 10.1. JSON Web Token claims . . . . . . . . . . . . . . . . . 6 68 10.2. PASSporT Types . . . . . . . . . . . . . . . . . . . . . 6 69 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 70 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 71 12.1. Normative References . . . . . . . . . . . . . . . . . . 7 72 12.2. Informative References . . . . . . . . . . . . . . . . . 7 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 75 1. Introduction 77 The SHAKEN [ATIS-1000074] specification defines a framework for using 78 STIR protocols including PASSporT [RFC8225], SIP Authenticated 79 Identity Management [RFC8224] and the STIR certificate framework 80 [RFC8226] for implementing the cryptographic validation of an 81 authorized originator of telephone calls using SIP. Because the 82 current telephone network contains both VoIP and TDM/SS7 originated 83 traffic, there are many scenarios that need to be accounted for where 84 PASSporT signatures may represent either direct or indirect call 85 origination scenarios. The SHAKEN [ATIS-1000074] specification 86 defines levels of attestation of the origination of the call as well 87 as an origination identifier that can help create a unique 88 association with the origination of calls from various parts of the 89 VoIP or TDM telephone network. This document specifies these 90 indicators as a specified PASSporT extension. 92 2. Terminology 94 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 95 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 96 document are to be interpreted as described in [RFC2119]. 98 3. Overview of 'shaken' PASSporT extension 100 The SHAKEN framework is designed to use PASSporT [RFC8225] as a 101 method of asserting the telephone number calling identity. In 102 addition to the PASSporT base claims, there are two additional claims 103 that have been defined for the needs of a service provider to signal 104 information beyond just the telephone identity. First, in order to 105 help bridge the transition of the state of the current telephone 106 network which has calls with no authentication and non-SIP [RFC3261] 107 signaling not compatible with the use of PASSporT and Secure 108 Telephone Identity (STI) in general, there is an attestation claim. 109 This provides three levels of attestation, including a full 110 attestation when the service provider can fully attest to the calling 111 identity, a partial attestation, when the service provider originated 112 a telephone call but can not fully attest to the calling identity, 113 and a gateway attestation which is the lowest level of attestation 114 and represents the service provider receiving a call from a non 115 PASSporT or STI supporting telephone gateway. 117 The second claim is a unique origination identifier that should be 118 used by the service provider to identify different sources of 119 telephone calls to support a traceback mechanism that can be used for 120 enforcement and identification of a source of illegitimate calls. 122 The use of the compact form of PASSporT is not specified in this 123 document and is not specified for use in SHAKEN [ATIS-1000074]. 125 The next two sections define these new claims. 127 4. PASSporT 'attest' Claim 129 This indicator allows for both identifying the service provider that 130 is vouching for the call as well as clearly indicating what 131 information the service provider is attesting to. The 'attest' claim 132 can be one of the following three values, 'A', 'B', or 'C' as defined 133 in [ATIS-1000074]. 135 'A' represents 'Full Attestation' where the signing provider MUST 136 satisfy all of the following conditions: 138 o Is responsible for the origination of the call onto the IP based 139 service provider voice network. 141 o Has a direct authenticated relationship with the initiator of the 142 call and can identify the customer associated with the initiator. 144 o Has established a verified association with the calling party 145 telephone number used for the call. 147 'B' represents 'Partial Attestation' where the signing provider MUST 148 satisfy all of the following conditions: 150 o Is responsible for the origination of the call onto its IP-based 151 voice network. 153 o Has a direct authenticated relationship with the initiator of the 154 call and can identify the customer associated with the initiator. 156 o Has NOT established a verified association with the calling party 157 telephone number being used for the call. 159 'C' represents 'Gateway Attestation' where the signing provider MUST 160 satisfy all of the following conditions: 162 o Is the entry point of the call into its VoIP network. 164 o Has no relationship with the initiator of the call (e.g., 165 international gateways) 167 5. PASSporT 'origid' Claim 169 The purpose of the unique origination identifier is to assign an 170 opaque identifier corresponding to the service provider-initiated 171 calls themselves, customers, classes of devices, or other groupings 172 that a service provider might want to use for determining things like 173 reputation or trace back identification of customers or gateways. 174 The value of 'origid' claim is a UUID as defined in [RFC4122]. 175 SHAKEN isn't prescriptive in the exact usage of origid other than the 176 UUID format as a globally unique identifier representing the 177 originator of the call to whatever granularity the PASSporT signer 178 determines is sufficient for the ability to trace the original 179 origination point of the call. There will likely be best practices 180 documents that more precisely guide it's usage in real deployments. 182 6. Example "shaken" PASSporT 183 Protected Header 184 { 185 "alg":"ES256", 186 "typ":"passport", 187 "ppt":"shaken", 188 "x5u":"https://cert.example.org/passport.cer" 189 } 190 Payload 191 { 192 "attest":"A" 193 "dest":{"uri":["sip:alice@example.com"]} 194 "iat":"1443208345", 195 "orig":{"tn":"12155551212"}, 196 "origid":"123e4567-e89b-12d3-a456-426655440000" 197 } 199 7. Using 'shaken' in SIP 201 The use of the 'shaken' PASSporT type and the claims 'attest' and 202 'origid' are formally defined in [ATIS-1000074] for usage in SIP 203 [RFC3261] aligned with the use of the identity header defined in 204 [RFC8224]. 206 8. Order of Claim Keys 208 The order of the claim keys MUST follow the rules of [RFC8225] 209 Section 9; the claim keys MUST appear in lexicographic order. 210 Therefore, the claim keys discussed in this document appear in the 211 PASSporT Payload in the following order, 213 o attest 215 o dest 217 o iat 219 o orig 221 o origid 223 9. Security Considerations 225 This document defines a new PASSporT [RFC8225] extension. The 226 considerations related to the security of the PASSporT object itself 227 are the same as those described in [RFC8225]. 229 [RFC8224] defines how to compare the values of the "dest", "orig" and 230 "iat" claims against fields in a SIP containing a PASSporT as part of 231 validating that request. The values of the new "attest" and "origid" 232 claims added by this extension are not used in such a validation 233 step. They are not compared to fields in the SIP message. Instead, 234 they simply carry additional information from the signer to the 235 consumer of the PASSport. This new information shares the same 236 integrity protection and non-repudiation properties as the base 237 claims in the PASSporT. 239 10. IANA Considerations 241 10.1. JSON Web Token claims 243 This specification requests that the IANA add two new claims to the 244 JSON Web Token Claims registry as defined in [RFC7519]. 246 Claim Name: "attest" 248 Claim Description: Attestation level as defined in SHAKEN framework 250 Change Controller: IESG 252 Specification Document(s): [RFCThis] 254 Claim Name: "origid" 256 Claim Description: Originating Identifier as defined in SHAKEN 257 framework 259 Change Controller: IESG 261 Specification Document(s): [RFCThis] 263 10.2. PASSporT Types 265 This specification requests that the IANA add a new entry to the 266 Personal Assertion Token (PASSporT) Extensions registry for the type 267 "shaken" which is specified in [RFCThis]. 269 11. Acknowledgements 271 The authors would like to thank those that helped review and 272 contribute to this document including specific contributions from Jon 273 Peterson, Russ Housley, and Andrew Jurczak. The authors would like 274 acknowledge the work of the ATIS/SIP Forum IP-NNI Task Force to 275 develop the concepts behind this document. 277 12. References 279 12.1. Normative References 281 [ATIS-1000074] 282 ATIS/SIP Forum NNI Task Group, "Signature-based Handling 283 of Asserted information using toKENs (SHAKEN)", January 284 2017, . 287 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 288 Unique IDentifier (UUID) URN Namespace", RFC 4122, 289 DOI 10.17487/RFC4122, July 2005, 290 . 292 [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token 293 (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, 294 . 296 [RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt, 297 "Authenticated Identity Management in the Session 298 Initiation Protocol (SIP)", RFC 8224, 299 DOI 10.17487/RFC8224, February 2018, 300 . 302 [RFC8225] Wendt, C. and J. Peterson, "PASSporT: Personal Assertion 303 Token", RFC 8225, DOI 10.17487/RFC8225, February 2018, 304 . 306 [RFC8226] Peterson, J. and S. Turner, "Secure Telephone Identity 307 Credentials: Certificates", RFC 8226, 308 DOI 10.17487/RFC8226, February 2018, 309 . 311 12.2. Informative References 313 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 314 Requirement Levels", BCP 14, RFC 2119, 315 DOI 10.17487/RFC2119, March 1997, 316 . 318 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 319 A., Peterson, J., Sparks, R., Handley, M., and E. 320 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 321 DOI 10.17487/RFC3261, June 2002, 322 . 324 Authors' Addresses 326 Chris Wendt 327 Comcast 328 One Comcast Center 329 Philadelphia, PA 19103 330 USA 332 Email: chris-ietf@chriswendt.net 334 Mary Barnes 335 iconectiv 337 Email: mary.ietf.barnes@gmail.com