PASSporT SHAKEN Extension (SHAKEN)
draft-ietf-stir-passport-shaken-05
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8588.
|
|
|---|---|---|---|
| Authors | Chris Wendt , Mary Barnes | ||
| Last updated | 2018-11-21 (Latest revision 2018-11-06) | ||
| Replaces | draft-wendt-stir-passport-shaken | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews |
GENART Last Call review
(of
-04)
by Francesca Palombini
Ready w/issues
|
||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Robert Sparks | ||
| Shepherd write-up | Show Last changed 2018-10-18 | ||
| IESG | IESG state | Became RFC 8588 (Proposed Standard) | |
| Consensus boilerplate | Yes | ||
| Telechat date |
(None)
Needs a YES. Needs 9 more YES or NO OBJECTION positions to pass. |
||
| Responsible AD | Adam Roach | ||
| Send notices to | Robert Sparks <rjsparks@nostrum.com> | ||
| IANA | IANA review state | IANA OK - Actions Needed |
draft-ietf-stir-passport-shaken-05
STIR C. Wendt
Internet-Draft Comcast
Intended status: Standards Track M. Barnes
Expires: May 10, 2019 iconectiv
November 06, 2018
PASSporT SHAKEN Extension (SHAKEN)
draft-ietf-stir-passport-shaken-05
Abstract
This document extends PASSporT, which is a token object that conveys
cryptographically-signed information about the participants involved
in communications. The extension is defined, corresponding to the
SHAKEN specification, to provide both a specific set of levels-of-
confidence to the correctness of the originating identity for a SIP
based Communication Service Provider (CSP) telephone network
originated call as well as an identifier that allows the CSP to
uniquely identify the origination of the call within its network.
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
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 10, 2019.
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
carefully, as they describe your rights and restrictions with respect
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of 'shaken' PASSporT extension . . . . . . . . . . . 3
4. PASSporT 'attest' Claim . . . . . . . . . . . . . . . . . . . 4
5. PASSporT 'origid' Claim . . . . . . . . . . . . . . . . . . . 4
6. Example "shaken" PASSporT . . . . . . . . . . . . . . . . . . 5
7. Using 'shaken' in SIP . . . . . . . . . . . . . . . . . . . . 5
8. Order of Claim Keys . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 6
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 6
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
11.1. JSON Web Token claims . . . . . . . . . . . . . . . . . 7
11.2. PASSporT Types . . . . . . . . . . . . . . . . . . . . . 7
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
13.1. Normative References . . . . . . . . . . . . . . . . . . 7
13.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Signature-based Handling of Asserted information using toKENs
(SHAKEN) [ATIS-1000074] specification defines a framework for using
Secure Telephone Identity Revisited (STIR) protocols including
PASSporT [RFC8225], SIP Authenticated Identity Management [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 values as claims to extend the base set of PASSporT
claims.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
In addition, the following terms are used in this document:
o Verified association: is typically defined as an authenticated
relationship with a device that initiated a call, for example, a
subscriber account with a specific SIM card or set of SIP
credentials.
o PASSporT: Defined in [RFC8225] is a JSON Web Token [RFC7519]
defined specifically for securing the identity of an initiator of
personal communication. This document defines a specific
extension to PASSporT.
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 and non-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 use of the compact form of PASSporT is not specified in this
document and is not specified for use in SHAKEN [ATIS-1000074].
The next two sections define these new claims.
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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 initiator of the
call and can identify the customer associated with the initiator.
o Has established a verified association with the calling party
telephone number used for the call.
'B' represents 'Partial Attestation' where the signing provider MUST
satisfy all of the following conditions:
o Is responsible for the origination of the call onto its IP-based
voice network.
o Has a direct authenticated relationship with the initiator of the
call and can identify the customer associated with the initiator.
o Has NOT established a verified association with the calling party
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].
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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.
6. Example "shaken" PASSporT
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":"12155550121"},
"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 field defined
in [RFC8224].
8. Order of Claim Keys
The order of the claim keys MUST follow the rules of [RFC8225]
Section 9; the claim keys MUST appear in lexicographic order.
Therefore, the claim keys discussed in this document appear in the
PASSporT Payload in the following order,
o attest
o dest
o iat
o orig
o origid
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9. Security Considerations
This document defines a new PASSporT [RFC8225] extension. The
considerations related to the security of the PASSporT object itself
are the same as those described in [RFC8225].
[RFC8224] defines how to compare the values of the "dest", "orig" and
"iat" claims against fields in a SIP containing a PASSporT as part of
validating that request. The values of the new "attest" and "origid"
claims added by this extension are not used in such a validation
step. They are not compared to fields in the SIP message. Instead,
they simply carry additional information from the signer to the
consumer of the PASSport. This new information shares the same
integrity protection and non-repudiation properties as the base
claims in the PASSporT.
10. Privacy Considerations
As detailed in [RFC3261] Section 26, SIP messages inherently carry
identifying information of the caller and callee. The value of the
'origid' claim, as defined in SHAKEN [ATIS-1000074] and described in
this document, is intended to be a opaque and unique identifier of an
element on the path of a given request. This identifier is used by
an originating telephone service provider to identify where within
their network (e.g. a gateway or particular service element) a call
was initiated. This facilitates identifying and stopping bad actors
trying to spoof identities or make fraudulent calls. The opacity of
the 'origid' claim value is intended to minimize direct exposure of
information about the origination of a set of calls sharing the
'origid' value. It should be recognized, however, that the potential
for discovering patterns through correlation of those calls exists.
This could allow a recipient of many calls to, for instance, learn
that a set of callers are using a particular service or coming
through a common gateway. However, this threat already exists in
SIP. There is information in the SIP messages(in the form of Record-
Route, Via, and potentially History-Info header field values that can
be analyzed the same way (and may correlate closely with the 'origid'
value). If the operator of an element is concerned about the
correlation of 'origid' values, the element could be configured to
use a unique 'origid' value per call in such a way that the operator
can associate those 'origid' values to the correct element when doing
lookups in their backend systems.
11. IANA Considerations
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11.1. 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]
11.2. PASSporT Types
This specification requests that the IANA add a new entry to the
Personal Assertion Token (PASSporT) Extensions registry for the type
"shaken" which is specified in [RFCThis].
12. Acknowledgements
The authors would like to thank those that helped review and
contribute to this document including specific contributions from Jon
Peterson, Russ Housley, Robert Sparks, and Andrew Jurczak. The
authors would like to acknowledge the work of the ATIS/SIP Forum IP-
NNI Task Force to develop the concepts behind this document.
13. References
13.1. Normative References
[ATIS-1000074]
ATIS/SIP Forum IP-NNI Task Group, "Signature-based
Handling of Asserted information using toKENs (SHAKEN)",
January 2017, <https://access.atis.org/apps/group_public/
download.php/32237/ATIS-1000074.pdf>.
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[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
<https://www.rfc-editor.org/info/rfc4122>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[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,
<https://www.rfc-editor.org/info/rfc8224>.
[RFC8225] Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
<https://www.rfc-editor.org/info/rfc8225>.
[RFC8226] Peterson, J. and S. Turner, "Secure Telephone Identity
Credentials: Certificates", RFC 8226,
DOI 10.17487/RFC8226, February 2018,
<https://www.rfc-editor.org/info/rfc8226>.
13.2. 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,
<https://www.rfc-editor.org/info/rfc2119>.
[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,
<https://www.rfc-editor.org/info/rfc3261>.
[RFC3323] Peterson, J., "A Privacy Mechanism for the Session
Initiation Protocol (SIP)", RFC 3323,
DOI 10.17487/RFC3323, November 2002,
<https://www.rfc-editor.org/info/rfc3323>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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Authors' Addresses
Chris Wendt
Comcast
One Comcast Center
Philadelphia, PA 19103
USA
Email: chris-ietf@chriswendt.net
Mary Barnes
iconectiv
Email: mary.ietf.barnes@gmail.com
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