stir C. Wendt Internet-Draft Comcast Intended status: Standards Track M. Barnes Expires: September 6, 2018 MLB@Realtime Communications March 05, 2018 PASSporT SHAKEN Extension (SHAKEN) draft-ietf-stir-passport-shaken-01 Abstract This document extends PASSporT, which is a token object that conveys cryptographically-signed information about the participants involved in communications, to include information defined as part of the SHAKEN specification from ATIS (Alliance for Telecommunications Industry Solutions) and the SIP Forum IP-NNI Joint Task Force. These extensions provide a level of confidence in the correctness of the originating identity for a telephone network that has communications coming from both STIR participating originating communications as well as communications that does not include STIR information. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 6, 2018. Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents Wendt & Barnes Expires September 6, 2018 [Page 1] Internet-Draft shaken March 2018 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Overview of 'shaken' PASSporT extension . . . . . . . . . . . 3 4. PASSporT 'attest' Claim . . . . . . . . . . . . . . . . . . . 3 5. PASSporT 'origid' Claim . . . . . . . . . . . . . . . . . . . 4 6. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7. Using 'shaken' in SIP . . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8.1. JSON Web Token claims . . . . . . . . . . . . . . . . . . 5 8.2. PASSporT Types . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 10.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction The SHAKEN [ATIS-1000074] specification defines a framework for using STIR protocols including PASSporT [RFC8225], RFC4474bis [RFC8224] and the STIR certificate framework [RFC8226] for implementing the cryptographic validation of an authorized originator of telephone calls using SIP. Because the current telephone network contains both VoIP and TDM/SS7 originated traffic, there are many scenarios that need to be accounted for where PASSporT signatures may represent either direct or indirect call origination scenarios. The SHAKEN [ATIS-1000074] specification defines levels of attestation of the origination of the call as well as an origination identifier that can help create a unique association with the origination of calls from various parts of the VoIP or TDM telephone network. This document specifies these indicators as a specified PASSporT extension. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Wendt & Barnes Expires September 6, 2018 [Page 2] Internet-Draft shaken March 2018 3. Overview of 'shaken' PASSporT extension The SHAKEN framework is designed to use PASSporT [RFC8225] as a method of asserting the telephone number calling identity. In addition to the PASSporT base claims, there are two additional claims that have been defined for the needs of a service provider to signal information beyond just the telephone identity. First, in order to help bridge the transition of the state of the current telephone network which has calls with no authentication and non-SIP [RFC3261] signaling not compatible with the use of PASSporT and Secure Telephone Identity (STI) in general, there is an attestation claim. This provides three levels of attestation, including a full attestation when the service provider can fully attest to the calling identity, a partial attestation, when the service provider originated a telephone call but can not fully attest to the calling identity, and a gateway attestation which is the lowest level of attestation and represents the service provider receiving a call from a non PASSporT or STI supporting telephone gateway. The second claim is a unique origination identifier that should be used by the service provider to identify different sources of telephone calls to support a traceback mechanism that can be used for enforcement and identification of a source of illegitimate calls. The next two sections define these new claims. 4. PASSporT 'attest' Claim This indicator allows for both identifying the service provider that is vouching for the call as well as clearly indicating what information the service provider is attesting to. The 'attest' claim can be one of the following three values, 'A', 'B', or 'C' as defined in [ATIS-1000074]. 'A' represents 'Full Attestation' where the signing provider MUST satisfy all of the following conditions: o Is responsible for the origination of the call onto the IP based service provider voice network. o Has a direct authenticated relationship with the customer and can identify the customer. o Has established a verified association with the telephone number used for the call. 'B' represents 'Partial Attestation' where the signing provider MUST satisfy all of the following conditions: Wendt & Barnes Expires September 6, 2018 [Page 3] Internet-Draft shaken March 2018 o Is responsible for the origination of the call onto its IP-based voice network. o Has a direct authenticated relationship with the customer and can identify the customer. o Has NOT established a verified association with the telephone number being used for the call. 'C' represents 'Gateway Attestation' where the signing provider MUST satisfy all of the following conditions: o Is the entry point of the call into its VoIP network. o Has no relationship with the initiator of the call (e.g., international gateways) 5. PASSporT 'origid' Claim The purpose of the unique origination identifier is to assign an opaque identifier corresponding to the service provider-initiated calls themselves, customers, classes of devices, or other groupings that a service provider might want to use for determining things like reputation or trace back identification of customers or gateways. The value of 'origid' claim is a UUID as defined in [RFC4122]. SHAKEN isn't prescriptive in the exact usage of origid other than the UUID format as a globally unique identifier representing the originator of the call to whatever granularity the PASSporT signer determines is sufficient for the ability to trace the original origination point of the call. There will likely be best practices documents that more precisely guide it's usage in real deployments. 6. Example Wendt & Barnes Expires September 6, 2018 [Page 4] Internet-Draft shaken March 2018 Protected Header { "alg":"ES256", "typ":"passport", "ppt":"shaken", "x5u":"https://cert.example.org/passport.cer" } Payload { "attest":"A" "dest":{"uri":["sip:alice@example.com"]} "iat":"1443208345", "orig":{"tn":"12155551212"}, "origid":"123e4567-e89b-12d3-a456-426655440000" } 7. Using 'shaken' in SIP The use of the 'shaken' PASSporT type and the claims 'attest' and 'origid' are formally defined in [ATIS-1000074] for usage in SIP [RFC3261] aligned with the use of the identity header defined in [RFC8224]. The carriage of the 'attest' and 'origid' values are in the full PASSporT token included in the identity header as specified in [ATIS-1000074]. 8. IANA Considerations 8.1. JSON Web Token claims This specification requests that the IANA add two new claims to the JSON Web Token Claims registry as defined in [RFC7519]. Claim Name: "attest" Claim Description: Attestation level as defined in SHAKEN framework Change Controller: IESG Specification Document(s): [RFCThis] Claim Name: "origid" Claim Description: Originating Identifier as defined in SHAKEN framework Change Controller: IESG Specification Document(s): [RFCThis] Wendt & Barnes Expires September 6, 2018 [Page 5] Internet-Draft shaken March 2018 8.2. PASSporT Types This specification requests that the IANA add a new entry to the PASSporT Types registry for the type "shaken" which is specified in [RFCThis]. 9. Acknowledgements The authors would like to thank those that helped review and contribute to this document including specific contributions from Jon Peterson, Russ Housley, and Andrew Jurczak. The authors would like acknowledge the work of the ATIS/SIP Forum IP-NNI Task Force to develop the concepts behind this document. 10. References 10.1. Normative References [ATIS-1000074] ATIS/SIP Forum NNI Task Group, "Signature-based Handling of Asserted information using toKENs (SHAKEN)", January 2017. [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, DOI 10.17487/RFC4122, July 2005, . [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, . [RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt, "Authenticated Identity Management in the Session Initiation Protocol (SIP)", RFC 8224, DOI 10.17487/RFC8224, February 2018, . [RFC8225] Wendt, C. and J. Peterson, "PASSporT: Personal Assertion Token", RFC 8225, DOI 10.17487/RFC8225, February 2018, . [RFC8226] Peterson, J. and S. Turner, "Secure Telephone Identity Credentials: Certificates", RFC 8226, DOI 10.17487/RFC8226, February 2018, . Wendt & Barnes Expires September 6, 2018 [Page 6] Internet-Draft shaken March 2018 10.2. Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, DOI 10.17487/RFC3261, June 2002, . Authors' Addresses Chris Wendt Comcast One Comcast Center Philadelphia, PA 19103 USA Email: chris-ietf@chriswendt.net Mary Barnes MLB@Realtime Communications Email: mary.ietf.barnes@gmail.com Wendt & Barnes Expires September 6, 2018 [Page 7]