draft-ietf-stir-rph-emergency-services-07.txt   rfc9027.txt 
STIR M. Dolly Internet Engineering Task Force (IETF) M. Dolly
Internet-Draft AT&T Request for Comments: 9027 AT&T
Intended status: Standards Track C. Wendt Category: Standards Track C. Wendt
Expires: September 12, 2021 Comcast ISSN: 2070-1721 Comcast
March 11, 2021 June 2021
Assertion Values for a Resource Priority Header Claim and a SIP Priority Assertion Values for Resource Priority Header and SIP Priority Header
Header Claim in Support of Emergency Services Networks Claims in Support of Emergency Services Networks
draft-ietf-stir-rph-emergency-services-07
Abstract Abstract
This document adds new assertion values for a Resource Priority This document adds new assertion values for a Resource Priority
Header ("rph") claim and a new SIP Priority Header claim ("sph") for Header ("rph") claim and a new SIP Priority Header ("sph") claim for
protection of the "psap-callback" value as part of the "rph" PASSporT protection of the "psap-callback" value as part of the "rph" Personal
extension, in support of the security of Emergency Services Networks Assertion Token (PASSporT) extension in support of the security of
for emergency call origination and callback. emergency services networks for emergency call origination and
callback.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
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time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on September 12, 2021. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9027.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology
3. New Assertion Values for "rph" claim . . . . . . . . . . . . 3 3. New Assertion Values for "rph" Claim
4. The SIP Priority header "sph" claim . . . . . . . . . . . . . 4 4. The SIP Priority Header ("sph") Claim
5. Order of Claim Keys . . . . . . . . . . . . . . . . . . . . . 5 5. Order of Claim Keys
6. Compact Form of PASSporT . . . . . . . . . . . . . . . . . . 6 6. Compact Form of PASSporT
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 7. IANA Considerations
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7.1. JSON Web Token Claims
8.1. JSON Web Token claims . . . . . . . . . . . . . . . . . . 6 8. Security Considerations
9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 6 9.2. Informative References
10.2. Informative References . . . . . . . . . . . . . . . . . 7 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses
1. Introduction 1. Introduction
Personal Assertion Token (PASSporT) Extension for Resource Priority "Personal Assertion Token (PASSporT) Extension for Resource Priority
Authorization [RFC8443] extended the Personal Assertion Token Authorization" [RFC8443] extended the Personal Assertion Token
(PASSporT) specification defined in [RFC8225] to allow the inclusion (PASSporT) specification defined in [RFC8225] to allow the inclusion
of cryptographically signed assertions of authorization for the of cryptographically signed assertions of authorization for the
values populated in the Session Initiation Protocol (SIP) "Resource- values populated in the Session Initiation Protocol (SIP) 'Resource-
Priority" header field [RFC4412]. [I-D.rosen-stir-emergency-calls] Priority' header field [RFC4412]. [EMERGENCY-CALLS] introduces the
introduces the need and justification for the protection of both the need and justification for the protection of both the SIP 'Resource-
SIP "Resource-Priority" and "Priority" header fields, used for Priority' and 'Priority' header fields, used for categorizing the
categorizing the priority use of the call in the telephone network, priority use of the call in the telephone network, specifically for
specifically for emergency calls. emergency calls.
Compromise of the SIP "Resource-Priority" or "Priority" header fields Compromise of the SIP 'Resource-Priority' or 'Priority' header fields
could lead to misuse of network resources (i.e., during congestion could lead to misuse of network resources (i.e., during congestion
scenarios), impacting the application services supported using the scenarios), impacting the application services supported using the
SIP "Resource-Priority" header field and the handling of Public SIP 'Resource-Priority' header field and the handling of Public
Saftey Answering Point (PSAP) callbacks. Safety Answering Point (PSAP) callbacks.
[RFC8225] allows extensions by which an authority on the originating [RFC8225] allows extensions by which an authority on the originating
side verifying the authorization of a particular communication for side verifying the authorization of a particular communication for
the SIP "Resource-Priority" header field or the SIP "Priority" header the SIP 'Resource-Priority' header field or the SIP 'Priority' header
field can use PASSPorT claims to cryptographically sign the field can use PASSporT claims to cryptographically sign the
information associated with either the SIP "Resource-Priority" or information associated with either the SIP 'Resource-Priority' or the
"Priority" header field and convey assertion of those values by the 'Priority' header field and convey assertion of those values by the
signing party authorization. A signed SIP "Resource-Priority" or signing party authorization. A signed SIP 'Resource-Priority' or
"Priority" header field will allow a receiving entity (including 'Priority' header field will allow a receiving entity (including
entities located in different network domains/boundaries) to verify entities located in different network domains/boundaries) to verify
the validity of assertions to act on the information with confidence the validity of assertions to act on the information with confidence
that the information has not been spoofed or compromised. that it has not been spoofed or compromised.
This document adds new "auth" array key values for a Resource This document adds new "auth" array key values for a Resource
Priority Header ("rph") claim defined in [RFC8443], in support of Priority Header ("rph") claim defined in [RFC8443], in support of
Emergency Services Networks for emergency call origination and emergency services networks for emergency call origination and
callback. This document additionally defines a new PASSporT claim, callback. This document additionally defines a new PASSporT claim,
"sph", including protection of the SIP Priority header field for the "sph", including protection of the SIP 'Priority' header field for
indication of an emergency service call-back assigned the value the indication of an emergency service callback assigned the value
"psap-callback" as defined in [RFC7090]. The use of the newly "psap-callback", as defined in [RFC7090]. The use of the newly
defined claim and key values corresponding to the SIP 'Resource- defined claim and key values corresponding to the SIP 'Resource-
Priority' and 'Priority' header fields for emergency services is Priority' and 'Priority' header fields for emergency services is
introduced in [I-D.rosen-stir-emergency-calls] but otherwise out-of- introduced in [EMERGENCY-CALLS] but otherwise is out of scope of this
scope of this document. In addition, the PASSPorT claims and values document. In addition, the PASSporT claims and values defined in
defined in this document are intended for use in environments where this document are intended for use in environments where there are
there are means to verify that the signer of the SIP 'Resource- means to verify that the signer of the SIP 'Resource-Priority' and
Priority' and 'Priority' header fields is authoritative. 'Priority' header fields is authoritative.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in
14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. New Assertion Values for "rph" claim 3. New Assertion Values for "rph" Claim
This specification defines the ability to sign the SIP Resource- This specification defines the ability to sign the SIP 'Resource-
Priority Header field namespace for local emergency communications Priority' header field namespace for local emergency communications
defined in [RFC7135] and represented by the string "esnet.x" where x defined in [RFC7135] and represented by the string "esnet.x", where x
is the priority-level allowed in the esnet namespace. As of the is the priority level allowed in the esnet namespace. As of the
writing of this specification the priority-level is between 0 and 4, writing of this specification, the priority level is between 0 and 4,
inclusive, but may be extended by future specifications. inclusive, but may be extended by future specifications.
Similar to the values defined by [RFC8443] for the "auth" JSON object Similar to the values defined by [RFC8443] for the "auth" JSON object
key inside the "rph" claim, the string "esnet.x" with the appropriate key inside the "rph" claim, the string "esnet.x" with the appropriate
value should be used when resource priority is required for local value should be used when resource priority is required for local
emergency communications corresponding and exactly matching the SIP emergency communications corresponding and exactly matching the SIP
Resource-Priority header field representing the namespace invoked in 'Resource-Priority' header field representing the namespace invoked
the call. in the call.
When using "esnet.x" as the "auth" assertion value in emergency When using "esnet.x" as the "auth" assertion value in emergency-
service destined calls, the "orig" claim of the PASSporT MUST service-destined calls, the "orig" claim of the PASSporT MUST
represent the calling party number that initiates the call to represent the calling party number that initiates the call to
emergency services. The "dest" claim MUST either be a country or emergency services. The "dest" claim MUST be either a country- or
region specific dial string (e.g., "911" for North America or "112" region-specific dial string (e.g., "911" for North America or a "112"
GSM defined string used in Europe and other countries) or GSM-defined string used in Europe and other countries) or
"urn:service:sos" as defined in [RFC5031], representing the emergency "urn:service:sos", as defined in [RFC5031], representing the
services destination of the call. emergency services destination of the call.
The following is an example of an "rph" claim for SIP 'Resource- The following is an example of an "rph" claim for the SIP 'Resource-
Priority' header field with an "esnet.1" assertion: Priority' header field with an "esnet.1" assertion:
{ {
"dest":{"uri":["urn:service:sos"]}, "dest":{"uri":["urn:service:sos"]},
"iat":1615471428, "iat":1615471428,
"orig":{"tn":"12155551212"}, "orig":{"tn":"12155551212"},
"rph":{"auth":["esnet.1"]} "rph":{"auth":["esnet.1"]}
} }
For emergency services callbacks, the "orig" claim of the "rph" For emergency services callbacks, the "orig" claim of the "rph"
PASSporT MUST represent the Public Saftey Answering Point (PSAP) PASSporT MUST represent the Public Safety Answering Point (PSAP)
telephone number. The "dest" claim MUST be the telephone number telephone number. The "dest" claim MUST be the telephone number
representing the original calling party of the emergency service call representing the original calling party of the emergency service call
that is being called back. that is being called back.
The following is an example of an "rph" claim for SIP 'Resource- The following is an example of an "rph" claim for the SIP 'Resource-
Priority' header field with a "esnet.0" assertion: Priority' header field with an "esnet.0" assertion:
{ {
"dest":{"tn":["12155551212"]}, "dest":{"tn":["12155551212"]},
"iat":1615471428, "iat":1615471428,
"orig":{"tn":"12155551213"}, "orig":{"tn":"12155551213"},
"rph":{"auth":["esnet.0"]} "rph":{"auth":["esnet.0"]}
} }
After the header and claims PASSporT objects have been constructed, After the header and claims PASSporT objects have been constructed,
their signature is generated normally per the guidance in [RFC8225] their signature is generated normally per the guidance in [RFC8225],
using the full form of PASSPorT. The credentials (i.e., Certificate) using the full form of PASSporT. The credentials (i.e., Certificate)
used to create the signature must have authority over the namespace used to create the signature must have authority over the namespace
of the "rph" claim, and there is only one authority per claim. The of the "rph" claim, and there is only one authority per claim. The
authority MUST use its credentials associated with the specific authority MUST use its credentials associated with the specific
service supported by the resource priority namespace in the claim. service supported by the resource priority namespace in the claim.
If r-values are added or dropped by the intermediaries along the If r-values are added or dropped by the intermediaries along the
path, the intermediaries must generate a new "rph" identity header path, the intermediaries must generate a new "rph" identity header
and sign the claim with their own authority. and sign the claim with their own authority.
4. The SIP Priority header "sph" claim 4. The SIP Priority Header ("sph") Claim
As defined in [RFC7090] the SIP Priority header field may be set to As defined in [RFC7090], the SIP 'Priority' header field may be set
the value "psap-callback" for emergency services callback calls. to the value "psap-callback" for emergency services callback calls.
Because some SIP networks may act on this value and provide priority Because some SIP networks may act on this value and provide priority
or other special routing based on this value, it is important to or other special routing based on this value, it is important to
protect and validate the authoritative use associated with it. protect and validate the authoritative use associated with it.
Therefore, we define a new claim key as part of the "rph" PASSporT, Therefore, we define a new claim key as part of the "rph" PASSporT,
"sph". This is an optional claim that MUST only be used only with an "sph". This is an optional claim that MUST only be used with an
"auth" claim with an "esnet.x" value indicating an authorized "auth" claim with an "esnet.x" value indicating an authorized
emergency callback call and corresponding to a SIP Priority header emergency callback call and corresponding to a SIP 'Priority' header
field with the value "psap-callback". field with the value "psap-callback".
The value of the "sph" claim key should only be "psap-callback" which The value of the "sph" claim key should only be "psap-callback",
MUST match the SIP Priority header field value for authorized which MUST match the SIP 'Priority' header field value for authorized
emergency services callbacks. If the value is anything other than emergency services callbacks. If the value is anything other than
"psap-callback", the PASSporT validation MUST be considered a failure "psap-callback", the PASSporT validation MUST be considered a failure
case. case.
Note: Because the intended use of this specification is only for Note that because the intended use of this specification is only for
emergency services, there is also an explicit assumption that the emergency services, there is also an explicit assumption that the
signer of the "rph" PASSporT can authoritatively represent both the signer of the "rph" PASSporT can authoritatively represent both the
content of the Resource Priority Header field and Priority Header content of the 'Resource-Priority' header field and 'Priority' header
field information associated specifically with a emergency services field information associated specifically with an emergency services
callback case where both could exist. This document is not intended callback case where both could exist. This document is not intended
to be a general mechanism for protecting SIP Priority Header fields, to be a general mechanism for protecting the SIP 'Priority' header
this could be accomplished as part of future work with a new PASSporT fields; this could be accomplished as part of future work with a new
extension or new claim added to either an existing PASSporT or PASSporT extension or new claim added to either an existing PASSporT
PASSporT extension usage. or PASSporT extension usage.
The following is an example of an "sph" claim for SIP 'Priority' The following is an example of an "sph" claim for the SIP 'Priority'
header field with the value "psap-callback": header field with the value "psap-callback":
{ {
"dest":{"tn":["12155551212"]}, "dest":{"tn":["12155551212"]},
"iat":1615471428, "iat":1615471428,
"orig":{"tn":"12155551213"}, "orig":{"tn":"12155551213"},
"rph":{"auth":["esnet.0"]}, "rph":{"auth":["esnet.0"]},
"sph":"psap-callback" "sph":"psap-callback"
} }
5. Order of Claim Keys 5. Order of Claim Keys
The order of the claim keys MUST follow the rules of [RFC8225] The order of the claim keys MUST follow the rules of Section 9 of
Section 9 which defines the deterministic JSON serialization used for [RFC8225], which defines the deterministic JSON serialization used
signature generation (and validation); the claim keys MUST appear in for signature generation (and validation); the claim keys MUST appear
lexicographic order. Therefore, the claim keys discussed in this in lexicographic order. Therefore, the claim keys discussed in this
document appear in the PASSporT Payload in the following order, document appear in the PASSporT Payload in the following order:
o dest * dest
o iat * iat
o orig * orig
o rph
o sph * rph
* sph
6. Compact Form of PASSporT 6. Compact Form of PASSporT
The use of the compact form of PASSporT is not specified in this The use of the compact form of PASSporT is not specified in this
document or recommended for 'rph' PASSporTs. document or recommended for "rph" PASSporTs.
7. Acknowledgements
The authors would like to thank Brian Rosen, Terry Reese, and Jon
Peterson for helpful suggestions, comments, and corrections.
8. IANA Considerations 7. IANA Considerations
8.1. JSON Web Token claims 7.1. JSON Web Token Claims
This specification requests that the IANA add one new claim to the This specification requests that the IANA add one new claim to the
JSON Web Token Claims registry as defined in [RFC7519]. "JSON Web Token Claims" registry, as defined in [RFC7519].
Claim Name: "sph"
Claim Description: SIP Priority header field
Change Controller: IESG
Specification Document(s): [RFCThis] Claim Name: sph
Claim Description: SIP Priority header field
Change Controller: IESG
Specification Document(s): RFC 9027
9. Security Considerations 8. Security Considerations
The security considerations discussed in [RFC8224], [RFC8225], and The security considerations discussed in [RFC8224], [RFC8225], and
[RFC8443] are applicable here. [RFC8443] are applicable here.
10. References 9. References
10.1. Normative References 9.1. Normative 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>.
[RFC4412] Schulzrinne, H. and J. Polk, "Communications Resource [RFC4412] Schulzrinne, H. and J. Polk, "Communications Resource
Priority for the Session Initiation Protocol (SIP)", Priority for the Session Initiation Protocol (SIP)",
RFC 4412, DOI 10.17487/RFC4412, February 2006, RFC 4412, DOI 10.17487/RFC4412, February 2006,
<https://www.rfc-editor.org/info/rfc4412>. <https://www.rfc-editor.org/info/rfc4412>.
[RFC5031] Schulzrinne, H., "A Uniform Resource Name (URN) for [RFC5031] Schulzrinne, H., "A Uniform Resource Name (URN) for
Emergency and Other Well-Known Services", RFC 5031, Emergency and Other Well-Known Services", RFC 5031,
DOI 10.17487/RFC5031, January 2008, DOI 10.17487/RFC5031, January 2008,
<https://www.rfc-editor.org/info/rfc5031>. <https://www.rfc-editor.org/info/rfc5031>.
skipping to change at page 7, line 19 skipping to change at line 297
[RFC7135] Polk, J., "Registering a SIP Resource Priority Header [RFC7135] Polk, J., "Registering a SIP Resource Priority Header
Field Namespace for Local Emergency Communications", Field Namespace for Local Emergency Communications",
RFC 7135, DOI 10.17487/RFC7135, May 2014, RFC 7135, DOI 10.17487/RFC7135, May 2014,
<https://www.rfc-editor.org/info/rfc7135>. <https://www.rfc-editor.org/info/rfc7135>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>. <https://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, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt, [RFC8224] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt,
"Authenticated Identity Management in the Session "Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 8224, Initiation Protocol (SIP)", RFC 8224,
DOI 10.17487/RFC8224, February 2018, DOI 10.17487/RFC8224, February 2018,
<https://www.rfc-editor.org/info/rfc8224>. <https://www.rfc-editor.org/info/rfc8224>.
[RFC8225] Wendt, C. and J. Peterson, "PASSporT: Personal Assertion [RFC8225] Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
Token", RFC 8225, DOI 10.17487/RFC8225, February 2018, Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
<https://www.rfc-editor.org/info/rfc8225>. <https://www.rfc-editor.org/info/rfc8225>.
[RFC8443] Singh, R., Dolly, M., Das, S., and A. Nguyen, "Personal [RFC8443] Singh, R., Dolly, M., Das, S., and A. Nguyen, "Personal
Assertion Token (PASSporT) Extension for Resource Priority Assertion Token (PASSporT) Extension for Resource Priority
Authorization", RFC 8443, DOI 10.17487/RFC8443, August Authorization", RFC 8443, DOI 10.17487/RFC8443, August
2018, <https://www.rfc-editor.org/info/rfc8443>. 2018, <https://www.rfc-editor.org/info/rfc8443>.
10.2. Informative References 9.2. Informative References
[I-D.rosen-stir-emergency-calls] [EMERGENCY-CALLS]
Rosen, B., "Non-Interactive Emergency Calls", draft-rosen- Rosen, B., "Non-Interactive Emergency Calls", Work in
stir-emergency-calls-00 (work in progress), March 2020. Progress, Internet-Draft, draft-rosen-stir-emergency-
calls-00, 9 March 2020, <https://tools.ietf.org/html/
draft-rosen-stir-emergency-calls-00>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Acknowledgements
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC The authors would like to thank Brian Rosen, Terry Reese, and Jon
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, Peterson for helpful suggestions, comments, and corrections.
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses Authors' Addresses
Martin Dolly Martin Dolly
AT&T AT&T
Email: md3135@att.com Email: md3135@att.com
Chris Wendt Chris Wendt
Comcast Comcast
Comcast Technology Center Comcast Technology Center
Philadelphia, PA 19103 Philadelphia, PA 19103
USA United States of America
Email: chris-ietf@chriswendt.net Email: chris-ietf@chriswendt.net
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