PASSporT Extension for Resource-Priority Authorization
draft-ietf-stir-rph-03
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (stir WG) | |
|---|---|---|---|
| Authors | Ray P. Singh , Martin Dolly , Subir Das , An Nguyen | ||
| Last updated | 2018-04-19 (Latest revision 2018-02-01) | ||
| Replaces | draft-singh-stir-rph | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text pdf htmlized pdfized bibtex | ||
| Reviews |
GENART Telechat review
Ready
SECDIR Telechat review
Has Nits
|
||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Russ Housley | ||
| Shepherd write-up | Show Last changed 2018-01-04 | ||
| IESG | IESG state | IESG Evaluation::Revised I-D Needed | |
| 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 | Russ Housley <rhousley@vigilsec.com> | ||
| IANA | IANA review state | IANA - Not OK |
draft-ietf-stir-rph-03
STIR R. Singh
Internet-Draft Vencore Labs
Intended status: Standards Track M. Dolly
Expires: August 5, 2018 AT&T
S. Das
Vencore Labs
A. Nguyen
Office of Emergency Communication/DHS
February 01, 2018
PASSporT Extension for Resource-Priority Authorization
draft-ietf-stir-rph-03
Abstract
This document extends the Secure Telephone Identity Revisited (STIR)
Personal Assertion Token (PASSporT) specification defined in
[I-D.ietf-stir-passport] to allow the inclusion of cryptographically
signed assertions of authorization for the values populated in the
Session Initiation Protocol (SIP) 'Resource-Priority' header field,
which is used for communications resource prioritization.
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-
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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 August 5, 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
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publication of this document. Please review these documents
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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PASSporT 'rph' Claim . . . . . . . . . . . . . . . . . . . . 3
4. 'rph' in SIP . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. Authentication Service Behavior . . . . . . . . . . . . . 5
4.2. Verification Service Behavior . . . . . . . . . . . . . . 5
5. Further Information Associated with 'Resource-Priority' . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. PASSporT Extension Claims Registration . . . . . . . . . 6
6.2. 'rph' Types . . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7.1. Avoidance of replay and cut and paste attacks . . . . . . 7
7.2. Solution Considerations . . . . . . . . . . . . . . . . . 7
7.3. Acknowledgements . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
PASSporT [I-D.ietf-stir-passport] is a token format based on JSON Web
Token (JWT) [RFC7519] for conveying cryptographically signed
information about the identities involved in personal communications;
it is used with STIR [I-D.ietf-stir-rfc4474bis] to convey a signed
assertion of the identity of the participants in real-time
communications established via a protocol like SIP [RFC3261]. This
specification extends PASSporT to allow cryptographic-signing of the
SIP 'Resource-Priority' header field defined in [RFC4412].
[RFC4412] defines the SIP 'Resource-Priority' header field for
communications Resource Priority. As specified in [RFC4412], the
'Resource-Priority' header field may be used by SIP user agents
[RFC3261], including Public Switched Telephone Network (PSTN)
gateways and terminals, and by SIP proxy servers, to influence
prioritization afforded to communication sessions, including PSTN
calls. However, the SIP 'Resource-Priority' header field could be
spoofed and abused by unauthorized entities.
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The STIR architecture [RFC7340] assumes that an authority on the
originating side of a call provides a cryptographic assurance of the
validity of the calling party number in order to prevent
impersonation attacks. The STIR architecture allows extensions that
can be utilized by authorities supporting real-time communication
services using the 'Resource-Priority' header field to
cryptographically sign the SIP 'Resource-Priority' header field and
convey assertion of the authorization for 'Resource-Priority'. For
example, the authority on the originating side verifying the
authorization of a particular communication for 'Resource-Priority'
can use a PASSPorT claim to cryptographically sign the SIP 'Resource-
Priority' header field and convey an assertion of the authorization
for 'Resource-Priority'. This will allow a receiving entity
(including entities located in different network domains/boundaries)
to verify the validity of assertions authorizing 'Resource-Priority'.
Cryptographically signed SIP 'Resource-Priority' header fields will
allow a receiving entity to verify and act on the information with
confidence that the information has not been spoofed or compromised.
This specification documents an optional extension to PASSporT and
the associated STIR mechanisms to provide a function to sign the SIP
'Resource-Priority' header field. This PASSporT object is used to
provide attestation of a calling user authorization for priority
communications. This is necessary in addition to the PASSporT object
that is used for calling user telephone number attestation. How the
optional extension to PASSporT is used for real-time communications
supported using SIP 'Resource-Priority' header field is outside the
scope of this document.
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 RFC 2119 [RFC2119] and
in RFC 8174 [RFC8174].
3. PASSporT 'rph' Claim
This specification defines a new JSON Web Token claim for "rph",
which provides an assertion for information in SIP 'Resource-
Priority' header field.
The creator of a PASSporT object adds a "ppt" value of "rph" to the
header of a PASSporT object, in which case the PASSporT claims MUST
contain a "rph" claim, and any entities verifying the PASSporT object
will be required to understand the "ppt" extension in order to
process the PASSporT in question. A PASSPorT header with the "ppt"
included will look as follows:
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{
"typ":"passport",
"ppt":"rph",
"alg":"ES256",
"x5u":"https://www.example.org/cert.cer"
}
The "rph" claim will provide an assertion of authorization, "auth",
for information in the SIP 'Resource-Priority' header field (i.e.,
Resource-Priority = "Resource-Priority": r-value, where r-value=
"namespace "." priority value") based on [RFC4412]. Specifically,
the "rph" claim includes assertion of the priority-level of the user
to be used for a given communication session. The value of the "rph"
claim is an Object with one or more keys. Each key is associated
with a JSON Array. These arrays contain Strings that correspond to
the r-values indicated in the SIP 'Resource-Priority' header field.
The following is an example "rph" claim for a SIP 'Resource-Priority'
header field with a r-value ="namespace "." priority value" of
"ets.0" and with another r-value= "namespace "." priority value" of
"wps.0".
{
"orig":{"tn":"12155550112"},
"dest":{["tn":"12125550113"]},
"iat":"1443208345",
"rph":{"auth":["ets.0", "wps.0"]}
}
After the header and claims PASSporT objects have been constructed,
their signature is generated normally per the guidance in
[I-D.ietf-stir-passport] using the full form of PASSPorT. The
credentials (e.g., authority responsible for authorizing Resource-
Priority) used to create the signature must have authority over the
namespace of the "rph" claim and there is only one authority per
claim. The authority MUST use its credentials (i.e., CERT)
associated with the specific service supported by the SIP namespace
in the claim. If r-values are added or dropped by the intermediaries
along the path, intermediaries must generate a new "rph" header and
sign the claim with its own authority.
The use of the compact form of PASSporT is not specified in this
document.
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4. 'rph' in SIP
This section specifies SIP-specific usage for the "rph" claim in
PASSporT.
4.1. Authentication Service Behavior
The Authentication Service will create the "rph" claim using the
values discussed in section 3 based on [RFC4412]. The construction
of "rph" claim follows the steps described in Section 4 of
[I-D.ietf-stir-rfc4474bis].
The resulting Identity header for "rph" might look as
follows(backslashes shown for line folding only):
Identity:eyJhbGciOiJFUzI1NiIsInBwdCI6InJwaCIsInR5cCI6InBhc3Nwb3J0\
IiwieDV1IjoiaHR0cHM6Ly93d3cuZXhhbXBsZS5jb20vY2VydC5jZXIifQo.eyJkZ\
XN0Ijp7WyJ0biI6IjEyMTI1NTUwMTEzIl19LCJpYXQiOiIxNDQzMjA4MzQ1Iiwib3\
JpZyI6eyJ0biI6IjEyMTU1NTUwMTEyIn0sInJwaCI6eyJhdXRoIjpbImV0cy4wIiw\
id3BzLjAiXX19Cg.s37S6VC8HM6Dl6YzJeQDsrZcwJ0lizxhUrA7f_98oWBHvo-cl\
-n8MIhoCr18vYYFy3blXvs3fslM_oos2P2Dyw;info=<https://www.example.\
org/cert.cer>;alg=ES256;ppt=rph
A SIP authentication service typically will derive the value of "rph"
from the 'Resource-Priority' header field based on policy associated
with service specific use of the "namespace "." priority value" for
r-values based on [RFC4412]. The authentication service derives the
value of the PASSPorT claim by verifying the authorization for
'Resource-Priority' (i.e., verifying a calling user privilege for
'Resource-Priority' based on its identity) which might be derived
from customer profile data or from access to external services.
[RFC4412] allows multiple "namespace "." priority value" pairs,
either in a single SIP 'Resource-Priority' header field or across
multiple SIP 'Resource-Priority' headers. An authority is
responsible for signing all the content of a SIP 'Resource-Priority'
header field for which it has the authority.
4.2. Verification Service Behavior
[I-D.ietf-stir-rfc4474bis] Section 6.2 Step 5 requires that
specifications defining "ppt" values describe any additional verifier
behavior. The behavior specified for the "ppt" values of "rph" is as
follows:
The verification service MUST extract the value associated with the
"auth" key in a full form PASSPorT with a "ppt" value of "rph". If
the signature validates, then the verification service can use the
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value of the "rph" claim as validation that the calling party is
authorized for 'Resource-Priority' as indicated in the claim. This
value would in turn be used for priority treatment in accordance with
local policy for the associated communication service. If the
signature validation fails, the verification service should infer
that the calling party is not authorized for 'Resource-Priority' as
indicated in the claim. In such cases, the priority treatment for
the associated communication service is handled as per the local
policy.
In addition, [I-D.ietf-stir-rfc4474bis] Section 6.2 Step 4 requires
"iat" value in "rph" claim to be verified.
The behavior of a SIP UA upon receiving an INVITE containing a
PASSporT object with a "rph" claim will largely remain a matter of
implementation policy for the specific communication service. In
most cases, implementations would act based on confidence in the
veracity of this information.
5. Further Information Associated with 'Resource-Priority'
There may be additional information about the calling party or the
call that could be relevant to authorization for 'Resource-Priority'.
This may include information related to the device subscription of
the caller, or to any institutions that the caller or device is
associated with, or even categories of institutions. All of these
data elements would benefit from the secure attestations provided by
the STIR and PASSporT frameworks. The specification of the "rph"
claim could entail the optional presence of one or more such
additional information fields.
A new IANA registry has been defined to hold potential values of the
"rph" array; see Section 6.2. The definition of the "rph" claim may
have one or more such additional information field(s). Details of
such "rph" claim to encompass other data elements are left for future
version of this specification.
6. IANA Considerations
6.1. PASSporT Extension Claims Registration
This document registers a new "ppt" value for the "Personal Assertion
Token (PASSporT) Extensions" table.
o Claim Name: "rph"
o Claim Description: Resource Priority Header Authorization
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o Change Controller: IESG
o Specification Document(s): Section 3 of [RFCThis]
6.2. 'rph' Types
This specification also requests that the IANA creates a new registry
for "rph" types. Each registry entry must contain two fields: the
name of the "rph" type and the specification in which the type is
described. This registry is to be initially populated with a single
value for "auth" which is specified in [RFCThis]. Registration of
new "rph" types shall be under the specification required policy.
7. Security Considerations
The security considerations discussed in [I-D.ietf-stir-rfc4474bis]
in Section 10 are applicable here.
7.1. Avoidance of replay and cut and paste attacks
The PASSporT extension with a "ppt" value of "rph" MUST only be sent
with SIP INVITE when 'Resource-Priority' header field is used to
convey the priority of the communication as defined in [RFC4412]. To
avoid the replay, and cut and paste attacks, the procedures described
in Section 10.1 of [I-D.ietf-stir-rfc4474bis] MUST be followed.
7.2. Solution Considerations
The use of extension to PASSporT tokens with "ppt" value "rph" based
on the validation of the digital signature and the associated
certificate requires consideration of the authentication and
authority or reputation of the signer to attest to the identity being
asserted. The following considerations should be recognized when
using PASSporT extension with "ppt" value of "rph":
o An authority (signer) is only allowed to sign the content of a SIP
'Resource-Priority' header field for which it has the right
authority. The authority that signs the token MUST have a secure
method for authentication of the end user or the device.
o The verification of the signature MUST include means of verifying
that the signer is authoritative for the signed content of the
resource priority namespace in the PASSporT.
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7.3. Acknowledgements
We would like to thank STIR members, ATIS/SIP Forum Task Force on
IPNNI members, and the NS/EP Priority Services community for
contributions to this problem statement and specification. We would
also like to thank David Hancock and Ning Zhang for their valuable
inputs.
8. References
8.1. Normative References
[I-D.ietf-stir-passport]
Wendt, C. and J. Peterson, "Personal Assertion Token
(PASSporT)", February 2017.
[I-D.ietf-stir-rfc4474bis]
Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
"Authenticated Identity Management in the Session
Initiation Protocol (SIP)", February 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://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,
<http://www.rfc-editor.org/info/rfc3261>.
[RFC4412] Schulzrinne, H. and J. Polk, "Communications Resource
Priority for the Session Initiation Protocol (SIP)",
RFC 4412, DOI 10.17487/RFC4412, February 2006,
<http://www.rfc-editor.org/info/rfc4412>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <http://www.rfc-editor.org/info/rfc8174>.
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8.2. Informative References
[RFC7340] Peterson, J., Schulzrinne, H., and H. Tschofenig, "Secure
Telephone Identity Problem Statement and Requirements",
RFC 7340, DOI 10.17487/RFC7340, September 2014,
<http://www.rfc-editor.org/info/rfc7340>.
Authors' Addresses
Ray P. Singh
Vencore Labs
150 Mount Airy Road
New Jersey, NJ 07920
USA
Email: rsingh@vencorelabs.com
Martin Dolly
AT&T
200 Laurel Avenue
Middletown, NJ 07748
USA
Email: md3135@att.com
Subir Das
Vencore Labs
150 Mount Airy Road
New Jersey, NJ 07920
USA
Email: sdas@vencorelabs.com
An Nguyen
Office of Emergency Communication/DHS
245 Murray Lane, Building 410
Washington, DC 20528
USA
Email: an.p.nguyen@HQ.DHS.GOV
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