wdiff draft-ietf-stir-rph-02.txt draft-ietf-stir-rph-03.txt

STIR R. Singh
Internet-Draft Vencore Labs
Intended status: Standards Track M. Dolly
Expires: July 8, August 5, 2018 AT&T
S. Das
Vencore Labs
A. Nguyen
Office of Emergency Communication/DHS
January 04,
February 01, 2018

PASSporT Extension for Resource-Priority Authorization
draft-ietf-stir-rph-02
draft-ietf-stir-rph-03

Abstract

This document extends the STIR PASSporT Secure Telephone Identity Revisited (STIR)
Personal Assertion Token (PASSporT) specification defined in
[I-D.ietf-stir-passport] to allow the inclusion of cryptographically-signed cryptographically
signed assertions of authorization for the values populated in the SIP
Session Initiation Protocol (SIP) 'Resource-Priority' header field,
which is used for communications resource prioritization.

Status of This Memo

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PASSporT 'rph' Claim . . . . . . . . . . . . . . . . . . . . 3
4. 'rph' in SIP . . . . . . . . . . . . . . . . . . . . . . . . 4 5
4.1. Authentication Service Behavior . . . . . . . . . . . . . 4 5
4.2. Verification Service Behavior . . . . . . . . . . . . . . 5
5. Further Information Associated with Resource-Priority . 'Resource-Priority' . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6.1. JSON Web Token PASSporT Extension Claims Registration . . . . . . . . . . . 6
6.2. PASSporT 'rph' Types . . . . . . . . . . . . . . . . . . 6 . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7.1. Avoidance of replay and cut and paste attacks . . . . . . 7
7.2. Solution Considerations . . . . . . . . . . . . . . . . . 7
7.3. Acknowledgements . . . . . . . . . . . . . . . . . . . . 7 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 7 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 9

1. Introduction

PASSporT [I-D.ietf-stir-passport] is a token format based on JWT JSON Web
Token (JWT) [RFC7519] for conveying cryptographically-signed 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. 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, including Public Switched Telephone Network (PSTN)
gateways and terminals, and by SIP proxy servers servers, to influence
prioritization afforded to communication sessions,including sessions, including PSTN
calls. However, the SIP 'Resource-Priority' header field could be
spoofed and abused by unauthorized entities.

The STIR architecture [RFC7340]assumes [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 extension 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 'Resource-Priority'
can use a PASSPorT claim to cryptographically-sign 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 'Resource-Priority'.
Cryptographically signed SIP 'Resource-Priority' headers header fields will
allow a receiving entity to verify and act on the information with
confidence that the information have 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 defined in
other documents and 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]. [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.
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:

{
"typ":"passport",
"ppt":"rph",
"alg":"ES256",
"x5u":"https://www.example.org/cert.cer"}
"x5u":"https://www.example.org/cert.cer"
}

The "rph" claim will provide an assertion of authorization,"auth", authorization, "auth",
for information in the SIP "Resource-Priority" 'Resource-Priority' header field (i.e.,
Resource-Priority: namespace
Resource-Priority = "Resource-Priority": r-value, where r-value=
"namespace "." r-priority) priority value") based on [RFC4412]. Specifically,
the "rph" claim includes assertion of the priority-
level priority-level of the user
to be used for a given communication session. The value of the "rph"
claim is an array containing Object with one or more of keys. Each key is associated
with a JSON
objects for Array. These arrays contain Strings that correspond to
the content of r-values indicated in the SIP 'Resource-Priority' header that is
being asserted of which one of the "rph" object, is mandatory. field.

The following is an example "rph" claim for a SIP "Resource-Priority" 'Resource-Priority'
header field with a "namespace r-value ="namespace "." r-priority" value priority value" of
"ets.0" and with a another r-value= "namespace "." r-priority" value priority value" of
"wps.0".

{ "orig":{"tn":"12155551212"}
"dest":{["tn":"12125551213"]},
"iat":1443208345,
"rph":{"auth":["ets.0","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.

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:

"eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJleUowZVhBaU9pSnd
ZWE56Y0c5eWRDSXNEUW9pY0hCMElqb2ljbkJvSWl3TkNpSmhiR2NpT2lKRlV6STFO
aUlzRFFvaWVEVjFJanBvZEhSd2N6b3ZMM2QzZHk1bGVHRnRjR3hsTG1OdmJTOWpaW
EowTG1ObGNuME5DZzBLIHx84oCZLuKAmXx8IGV5QWliM0pwWnlJNmV5SjBiaUk2SW
pFeU1UVTFOVFV4TWpFeUluME5DaUprWlhOMElqcDdXeUowYmlJNklqRXlNVEkxTlR
VeE1qRXpJbDE5TEEwS0ltbGhkQ0k2TVRRME16SXdPRE0wTlN3TkNpSnljR2dpT25z
aVlYVjBhQ0k2V3lKbGRITXVNQ0lzSW5kd2N5NHdJbDE5RFFvPSJ9.s37S6VC8HM6D
l6YzJeQDsrZcwJ0lizxhUrA7f_98oWBHvo-cl-n8MIhoCr18vYYFy3blXvs3fslM_
oos2P2Dyw"; info= "https://www.example.org/cert.cer";alg=ES256;
ppt="rph"
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 "." r-priority" values 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
'Resource-Priority' (i.e., verifying a calling user privilege for Resource-
Priority
'Resource-Priority' based on its identity) which might be derived
from customer profile data or from access to external services.

[RFC4412] allows multiple "namespace "." r-priority" priority value" pairs,
either in a single SIP Resource-Priority 'Resource-Priority' header field or across
multiple SIP
Resource-Priority 'Resource-Priority' headers. However, it is not necessary to sign all
content of a SIP Resource-Priority header or all SIP Resource-
Priority headers in a given SIP message. An authority is only
responsible for signing all the content of a SIP Resource-Priority 'Resource-Priority'
header field for which it has authority (e.g., a specific "namespace "."
r-priority"). 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
value of the "rph" claim as validation that the calling party is
authorized for Resource-Priority, which '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 UAs 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 cases, implementations would act based on confidence in the
veracity of this information. The use of the compact form of
PASSporT is not specified in this document.

5. Further Information Associated with Resource-Priority 'Resource-Priority'

There may be additional information about the calling party or the
call that could be relevant to authorization for Resource-Priority. '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. JSON Web Token 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
o Change Controller: IESG

o Specification Document(s): Section 3 of [RFCThis]

6.2. PASSporT 'rph' Types

This document requests that the IANA add a new entry to the PASSporT
Types registry for the type "rph" which is specified in [RFCThis].
This specification also requests that the IANA create creates a new registry
for PASSporT "rph" types. Registration Each registry entry must contain two fields: the
name of new PASSporT the "rph" types
shall be under type and the specification required policy. 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 SIP
'Resource-Priority' header.
resource priority namespace in the PASSporT.

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 his 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>.

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