Assertion Values for a Resource Priority Header Claim in Support of Emergency Services Networks
draft-ietf-stir-rph-emergency-services-01
STIR M. Dolly
Internet-Draft AT&T
Intended status: Standards Track C. Wendt
Expires: September 10, 2020 Comcast
March 09, 2020
Assertion Values for a Resource Priority Header Claim in Support of
Emergency Services Networks
draft-ietf-stir-rph-emergency-services-01
Abstract
This document adds new assertion values for a Resource Priority
Header ("rph") claim defined in RFC 8443, in support of Emergency
Services Networks for emergency call origination and callback.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. New Assertion Values . . . . . . . . . . . . . . . . . . . . 3
3.1. ESorig . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. EScallback . . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4.1. PASSporT Resource Priority Header (rph) Types . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Personal Assertion Token (PASSporT) Extension for Resource Priority
Authorization [RFC8443] extended the Personal Assertion Token
(PASSporT) specification defined in [RFC8225] 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.
Compromise of the SIP 'Resource-Priority' header field [RFC4412]
could lead to misuse of network resources (i.e., during congestion
scenarios), impacting the application services supported using the
SIP 'Resource-Priority' header field.
[RFC8225] allows extensions by which an authority on the originating
side verifying the authorization of a particular communication for
the SIP 'Resource-Priority' header field can use a PASSPorT claim to
cryptographically sign the SIP 'Resource-Priority' header field and
convey assertion of the authorization for the SIP 'Resource-Priority'
header field. A signed SIP 'Resource-Priority' header field will
allow a receiving entity (including entities located in different
network domains/boundaries) to verify the validity of assertions
authorizing the SIP 'Resource-Priority' header field and to act on
the information with confidence that the information has not been
spoofed or compromised.
This document adds new assertion values for a Resource Priority
Header ("rph") claim defined in [RFC8443], in support of Emergency
Services Networks for emergency call origination and callback. How
these new assertion values for real-time communications supported
using the SIP 'Resource-Priority' header field is outside the scope
of this document. In addition, the PASSPorT extension defined in
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this document is intended for use in environments where there are
means to verify that the signer of the SIP 'Resource-Priority' header
field is authoritative.
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.
3. New Assertion Values
This specification defines new assertions values for:
* "ESorig": Emergency Services call origination
* "EScallback": Emergency Services callback.
3.1. ESorig
When using "ESorig" as the "rph" assertion value, the "orig" claim of
the PASSporT MUST represent the calling party number that initiates
the call to emergency services. The "dest" claim MUST either be a
country or region specific dial string (e.g., "911" for North America
or "112" GSM defined string used in Europe and other countries) or
"urn:service:sos" as defined in TBD, representing the emergency
services destination of the call.
The following is an example of an "rph" claim for SIP 'Resource-
Priority' header field with a "ESorig" assertion:
{
"orig":{"tn":"12155551212"},
"dest":{["tn":"urn:service:sos"]},
"iat":1443208345,
"rph":{"ESorig":["esnet,x"]}
}
3.2. EScallback
When using "EScallback" as the "rph" assertion value, the "orig"
claim of the PASSporT MUST represent the emergency network telephone
number. The "dest" claim MUST be the telephone number representing
the original calling party of the emergency service call that is
being called back.
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The following is an example of an "rph" claim for SIP 'Resource-
Priority' header field with a "EScallback" assertion:
{
"orig":{"tn":"12155551213"},
"dest":{["tn":"12155551212"]},
"iat":1443208345,
"rph":{"EScallback":["esnet,x"]}
}
After the header and claims PASSporT objects have been constructed,
their signature is generated normally per the guidance in [RFC8225]
using the full form of PASSPorT. The credentials (i.e., Certificate)
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 associated with the specific
service supported by the resource priority namespace in the claim.
If r-values are added or dropped by the intermediaries along the
path, the intermediaries must generate a new "rph" header and sign
the claim with their own authority.
The use of the compact form of PASSporT is not specified in this
document.
4. IANA Considerations
4.1. PASSporT Resource Priority Header (rph) Types
This specification requests that the IANA add two new assertion
values to the "PASSporT Resource Priority Header (rph) Types"
Registry as defined in [RFC8443].
The following assertion values will be added to the registry:
* "ESorig": Emergency Services call origination
* "EScallback": Emergency Services callback
+--------------+------------+
| rph Type | Reference |
+--------------+------------+
| ESorig | [this RFC] |
+--------------+------------+
| EScallback | [this RFC] |
+--------------+------------+
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5. Security Considerations
The security considerations discussed in [RFC8224], Section 12, are
applicable here.
6. References
6.1. Normative References
[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>.
[RFC4412] Schulzrinne, H. and J. Polk, "Communications Resource
Priority for the Session Initiation Protocol (SIP)",
RFC 4412, DOI 10.17487/RFC4412, February 2006,
<https://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,
<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>.
[RFC8443] Singh, R., Dolly, M., Das, S., and A. Nguyen, "Personal
Assertion Token (PASSporT) Extension for Resource Priority
Authorization", RFC 8443, DOI 10.17487/RFC8443, August
2018, <https://www.rfc-editor.org/info/rfc8443>.
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6.2. 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>.
[RFC7340] Peterson, J., Schulzrinne, H., and H. Tschofenig, "Secure
Telephone Identity Problem Statement and Requirements",
RFC 7340, DOI 10.17487/RFC7340, September 2014,
<https://www.rfc-editor.org/info/rfc7340>.
[RFC7375] Peterson, J., "Secure Telephone Identity Threat Model",
RFC 7375, DOI 10.17487/RFC7375, October 2014,
<https://www.rfc-editor.org/info/rfc7375>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[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>.
Authors' Addresses
Martin Dolly
AT&T
Email: md3135@att.com
Chris Wendt
Comcast
Comcast Technology Center
Philadelphia, PA 19103
USA
Email: chris-ietf@chriswendt.net
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