Internet DRAFT - draft-ietf-acme-authority-token-tnauthlist
draft-ietf-acme-authority-token-tnauthlist
Network Working Group C. Wendt
Internet-Draft Somos Inc.
Intended status: Standards Track D. Hancock
Expires: 11 August 2023 Comcast
M. Barnes
J. Peterson
Neustar Inc.
7 February 2023
TNAuthList profile of ACME Authority Token
draft-ietf-acme-authority-token-tnauthlist-13
Abstract
This document defines a profile of the Automated Certificate
Management Environment (ACME) Authority Token for the automated and
authorized creation of certificates for VoIP Telephone Providers to
support Secure Telephony Identity (STI) using the TNAuthList defined
by STI certificates.
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
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 11 August 2023.
Copyright Notice
Copyright (c) 2023 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 to this document. Code Components
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extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. ACME new-order identifiers for TNAuthList . . . . . . . . . . 3
4. TNAuthList Identifier Authorization . . . . . . . . . . . . . 5
5. TNAuthList Authority Token . . . . . . . . . . . . . . . . . 7
5.1. "iss" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. "exp" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.3. "jti" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.4. "atc" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.5. Acquiring the token from the Token Authority . . . . . . 8
5.6. Token Authority Responsibilities . . . . . . . . . . . . 10
5.7. Scope of the TNAuthList . . . . . . . . . . . . . . . . . 10
6. Validating the TNAuthList Authority Token . . . . . . . . . . 10
7. Using ACME-issued Certificates with JSON Web Signature . . . 11
8. Usage Considerations . . . . . . . . . . . . . . . . . . . . 13
8.1. Large number of Non-contiguous TNAuthList values . . . . 13
9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
12.1. Normative References . . . . . . . . . . . . . . . . . . 14
12.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
[RFC8555] is a mechanism for automating certificate management on the
Internet. It enables administrative entities to prove effective
control over resources like domain names, and automates the process
of generating and issuing certificates.
[I-D.ietf-acme-authority-token] extends ACME to provide a general
method of extending the authority and authorization of entities to
control a resource via a third party Token Authority beyond the
Certification Authority (CA).
This document is a profile document using the Authority Token
mechanism defined in [I-D.ietf-acme-authority-token]. It is a
profile that specifically addresses the STIR problem statement
[RFC7340] which identifies the need for Internet credentials that can
attest authority for the originator of VoIP calls in order to detect
impersonation, which is currently an enabler for common attacks
associated with illegal robocalling, voicemail hacking, and swatting.
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These credentials are used to sign PASSporTs [RFC8225], which can be
carried in using protocols such as SIP [RFC8224]. Currently, the
only defined credentials for this purpose are the certificates
specified in [RFC8226] using the TNAuthList. This document defines
the use of the TNAuthList Authority Token in the ACME challenge to
proof the authoritative use of the contents of the TNAuthList,
including a Service Provider Token (SPC), a Telephone Number, or a
set of telephone numbers or telephone number blocks.
This document also describes the ability for a telephone authority to
authorize the creation of CA types of certificates for delegation as
defined in [RFC9060].
2. Terminology
The keywords "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. ACME new-order identifiers for TNAuthList
In [RFC8555], Section 7 defines the procedure that an ACME client
uses to order a new certificate from a CA. The new-order request
contains an identifier field that specifies the identifier objects
the order corresponds to. This draft defines a new type of
identifier object called TNAuthList. A TNAuthList identifier
contains the identity information to be populated in the TN
Authorization List of the new certificate. For the TNAuthList
identifier, the new-order request includes a type set to the string
"TNAuthList". The value of the TNAuthList identifier MUST be set to
the details of the TNAuthList requested.
The format of the string that represents the TNAuthList MUST be
constructed using base64url encoding, as per [RFC8555] base64url
encoding described in Section 5 of [RFC4648] according to the profile
specified in JSON Web Signature in Section 2 of [RFC7515]. The
base64url encoding MUST NOT include any padding characters and the
TNAuthList ASN.1 object MUST encoded using DER encoding rules.
An example of an ACME order object “identifiers” field containing a
TNAuthList certificate would look as follows,
"identifiers": [{"type":"TNAuthList","value":"F83n2a...avn27DN3"}]
where the "value" object string represents the arbitrary length
base64url encoded string.
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A full new-order request would look as follows,
POST /acme/new-order HTTP/1.1
Host: example.com
Content-Type: application/jose+json
{
"protected": base64url({
"alg": "ES256",
"kid": "https://example.com/acme/acct/evOfKhNU60wg",
"nonce": "5XJ1L3lEkMG7tR6pA00clA",
"url": "https://example.com/acme/new-order"
}),
"payload": base64url({
"identifiers": [{"type":"TNAuthList","value":"F83n...n27DN3"}],
"notBefore": "2021-01-01T00:00:00Z",
"notAfter": "2021-01-08T00:00:00Z"
}),
"signature": "H6ZXtGjTZyUnPeKn...wEA4TklBdh3e454g"
}
On receiving a valid new-order request, the ACME server creates an
authorization object, [RFC8555] Section 7.1.4, containing the
challenge that the ACME client must satisfy to demonstrate authority
for the identifiers specified by the new order (in this case, the
TNAuthList identifier). The CA adds the authorization object URL to
the "authorizations" field of the order object, and returns the order
object to the ACME client in the body of a 201 (Created) response.
HTTP/1.1 201 Created
Content-Type: application/json
Replay-Nonce: MYAuvOpaoIiywTezizk5vw
Location: https://example.com/acme/order/1234
{
"status": "pending",
"expires": "2022-01-08T00:00:00Z",
"notBefore": "2022-01-01T00:00:00Z",
"notAfter": "2022-01-08T00:00:00Z",
"identifiers":[{"type":"TNAuthList",
"value":"F83n2a...avn27DN3"}],
"authorizations": [
"https://example.com/acme/authz/1234"
],
"finalize": "https://example.com/acme/order/1234/finalize"
}
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4. TNAuthList Identifier Authorization
On receiving the new-order response, the ACME client queries the
referenced authorization object to obtain the challenges for the
identifier contained in the new-order request as shown in the
following example request and response.
POST /acme/authz/1234 HTTP/1.1
Host: example.com
Content-Type: application/jose+json
{
"protected": base64url({
"alg": "ES256",
"kid": " https://example.com/acme/acct/evOfKhNU60wg",
"nonce": "uQpSjlRb4vQVCjVYAyyUWg",
"url": "https://example.com/acme/authz/1234"
}),
"payload": "",
"signature": "nuSDISbWG8mMgE7H...QyVUL68yzf3Zawps"
}
HTTP/1.1 200 OK
Content-Type: application/json
Link: <https://example.com/acme/some-directory>;rel="index"
{
"status": "pending",
"expires": "2022-01-08T00:00:00Z",
"identifier": {
"type":"TNAuthList",
"value":"F83n2a...avn27DN3"
},
"challenges": [
{
"type": "tkauth-01",
"tkauth-type": "atc",
"token-authority": "https://authority.example.org",
"url": "https://example.com/acme/chall/prV_B7yEyA4",
"token": "IlirfxKKXAsHtmzK29Pj8A"
}
]
}
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When processing a certificate order containing an identifier of type
"TNAuthList", a CA uses the Authority Token challenge type of
"tkauth-01" with a "tkauth-type" of "atc" in
[I-D.ietf-acme-authority-token] to verify that the requesting ACME
client has authenticated and authorized control over the requested
resources represented by the "TNAuthList" value.
The challenge "token-authority" parameter is only used in cases where
the VoIP telephone network requires the CA to identify the Token
Authority. This is currently not the case for the SHAKEN
[ATIS-1000080] certificate framework governance, but may be used by
other frameworks. If a "token-authority" parameter is present, then
the ACME client MAY use the "token-authority" value to identify the
URL representing the Token Authority that will provide the TNAuthList
Authority Token response to the challenge. If the "token-authority"
parameter is not present, then the ACME client MUST identify the
Token Authority based on locally configured information or local
policies.
The ACME client responds to the challenge by posting the TNAuthList
Authority Token to the challenge URL identified in the returned ACME
authorization object, an example of which follows.
POST /acme/chall/prV_B7yEyA4 HTTP/1.1
Host: boulder.example.com
Content-Type: application/jose+json
{
"protected": base64url({
"alg": "ES256",
"kid": "https://example.com/acme/acct/evOfKhNU60wg",
"nonce": "Q_s3MWoqT05TrdkM2MTDcw",
"url": "https://boulder.example.com/acme/authz/asdf/0"
}),
"payload": base64url({
"tkauth": "DGyRejmCefe7v4N...vb29HhjjLPSggwiE"
}),
"signature": "9cbg5JO1Gf5YLjjz...SpkUfcdPai9uVYYQ"
}
The "tkauth" field is defined as a new field in the challenge object
specific to the tkauth-01 challenge type that should contain the
TNAuthList Authority Token defined in the next section.
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5. TNAuthList Authority Token
The Telephone Number Authority List Authority Token (TNAuthList
Authority Token) is a profile instance of the ACME Authority Token
defined in [I-D.ietf-acme-authority-token].
The TNAuthList Authority Token Protected header MUST comply with the
Authority Token Protected header as defined in
[I-D.ietf-acme-authority-token].
The TNAuthList Authority Token Payload MUST include the mandatory
claims "exp", "jti", and "atc", and MAY include the optional claims
defined for the Authority Token detailed in the next subsections.
5.1. "iss" claim
The "iss" claim is an optional claim defined in [RFC7519]
Section 4.1.1. It can be used as a URL identifying the Token
Authority that issued the TNAuthList Authority Token beyond the "x5u"
or other Header claims that identify the location of the certificate
or certificate chain of the Token Authority used to validate the
TNAuthList Authority Token.
5.2. "exp" claim
The "exp" claim, defined in [RFC7519] Section 4.1.4, MUST be included
and contains the DateTime value of the ending date and time that the
TNAuthList Authority Token expires.
5.3. "jti" claim
The "jti" claim, defined in [RFC7519] Section 4.1.7, MUST be included
and contains a unique identifier for this TNAuthList Authority Token
transaction.
5.4. "atc" claim
The "atc" claim MUST be included and is defined in
[I-D.ietf-acme-authority-token]. It contains a JSON object with the
following elements:
* a "tktype" key with a string value equal to "TNAuthList" to
represent a TNAuthList profile of the authority token
[I-D.ietf-acme-authority-token] defined by this document. "tktype"
is a required key and MUST be included.
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* a "tkvalue" key with a string value equal to the base64url
encoding of the TN Authorization List certificate extension ASN.1
object using DER encoding rules. "tkvalue" is a required key and
MUST be included.
* a "ca" key with a boolean value set to either true when the
requested certificate is allowed to be a CA cert for delegation
uses or false when the requested certificate is not intended to be
a CA cert, only an end-entity certificate. "ca" is an optional
key, if not included the "ca" value is considered false by
default.
* a "fingerprint" key is constructed as defined in [RFC8555]
Section 8.1 corresponding to the computation of the "Thumbprint"
step using the ACME account key credentials. "fingerprint" is a
required key and MUST be included.
An example of the TNAuthList Authority Token is as follows:
{
"protected": base64url({
"typ":"JWT",
"alg":"ES256",
"x5u":"https://authority.example.org/cert"
}),
"payload": base64url({
"iss":"https://authority.example.org",
"exp":1640995200,
"jti":"id6098364921",
"atc":{"tktype":"TNAuthList",
"tkvalue":"F83n2a...avn27DN3",
"ca":false,
"fingerprint":"SHA256 56:3E:CF:AE:83:CA:4D:15:B0:29:FF:1B:71:
D3:BA:B9:19:81:F8:50:9B:DF:4A:D4:39:72:E2:B1:F0:B9:38:E3"}
}),
"signature": "9cbg5JO1Gf5YLjjz...SpkUfcdPai9uVYYQ"
}
5.5. Acquiring the token from the Token Authority
Following [I-D.ietf-acme-authority-token] Section 5, the authority
token should be acquired using a RESTful HTTP POST transaction as
follows:
POST /at/account/:id/token HTTP/1.1
Host: authority.example.org
Content-Type: application/json
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The request will pass the account id as a string in the request
parameter "id". This string will be managed as an identifier
specific to the Token Authority's relationship with a communications
service provider (CSP). There is assumed to also be a corresponding
authentication procedure that can be verified for the success of this
transaction. For example, an HTTP authorization header containing a
valid authorization credentials as defined in [RFC7231] Section 14.8.
The body of the POST request MUST contain a JSON object with key
value pairs corresponding to values that are requested as the content
of the claims in the issued token. As an example, the body SHOULD
contain a JSON object as follows:
{
"tktype":"TNAuthList",
"tkvalue":"F83n2a...avn27DN3",
"ca":false,
"fingerprint":"SHA256 56:3E:CF:AE:83:CA:4D:15:B0:29:FF:1B:71:D3
:BA:B9:19:81:F8:50:9B:DF:4A:D4:39:72:E2:B1:F0:B9:38:E3"
}
The response to the POST request if successful returns a 200 OK with
a JSON body that contains, at a minimum, the TNAuthList Authority
Token as a JSON object with a key of "token" and the base64url
encoded string representing the atc token. JSON is easily
extensible, so users of this specification may want to pass other
pieces of information relevant to a specific application.
An example successful response would be as follows:
HTTP/1.1 200 OK
Content-Type: application/json
{"token": "DGyRejmCefe7v4N...vb29HhjjLPSggwiE"}
If the request is not successful, the response should indicate the
error condition. Specifically, for the case that the authorization
credentials are invalid or if the Account ID provided does not exist,
the response code MUST be 403 - Forbidden. Other 4xx and 5xx
responses MUST follow standard [RFC7231] HTTP error condition
conventions.
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5.6. Token Authority Responsibilities
When creating the TNAuthList Authority Token, the Token Authority
MUST validate that the information contained in the ASN.1 TNAuthList
accurately represents the service provider code (SPC) or telephone
number (TN) resources the requesting party is authorized to represent
based on their pre-established and verified secure relationship
between the Token Authority and the requesting party. Note that the
fingerprint in the token request is not meant to be verified by the
Token Authority, but rather is meant to be signed as part of the
token so that the party that requests the token can, as part of the
challenge response, allow the ACME server to validate the token
requested and used came from the same party that controls the ACME
client.
5.7. Scope of the TNAuthList
Because this specification specifically involves the TNAuthList
defined in [RFC8226] which involves SPC, TNBlock, and individual TNs,
the client may also request an Authority Token with some subset of
its own authority as the TNAuthList provided in the "tkvalue" element
in the "atc" JSON object. Generally, the scope of authority
representing a communications service provider is represented by a
particular SPC (e.g. in North America, an operating company number
(OCN) or service provider identifier (SPID)). That provider is also
generally associated, based on number allocations, with a particular
set of different TN Blocks and/or TNs. TNAuthList can be constructed
to define a limited scope of the TNBlocks or TNs either associated
with an SPC or with the scope of TN Blocks or TNs the client has
authority over.
As recommended in [I-D.ietf-acme-authority-token] security
considerations, an Authority Token can either have a scope that
attests all of the resources which a client is eligible to receive
certificates for, or potentially a more limited scope that is
intended to capture only those resources for which a client will
receive a certificate from a particular certification authority. Any
certification authority that sees an Authority Token can learn
information about the resources a client can claim. In cases where
this incurs a privacy risk, Authority Token scopes should be limited
to only the resources that will be attested by the requested ACME
certificate.
6. Validating the TNAuthList Authority Token
Upon receiving a response to the challenge, the ACME server MUST
perform the following steps to determine the validity of the
response.
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* Verify that the value of the "atc" claim is a well-formed JSON
object containing the mandatory key values.
* If there is an "x5u" parameter verify the "x5u" parameter is a
HTTPS URL with a reference to a certificate representing the
trusted issuer of authority tokens for the eco-system.
* If there is an "x5c" parameter verify the certificate array
contains a certificate representing the trusted issuer of
authority tokens for the eco-system.
* Verify the TNAuthList Authority Token signature using the public
key of the certificate referenced by the token's "x5u" or "x5c"
parameter.
* Verify that "atc" claim contains a "tktype" identifier with the
value "TNAuthList".
* Verify that the "atc" claim "tkvalue" identifier contains the
equivalent base64url encoded TNAuthList certificate extension
string value as the Identifier specified in the original
challenge.
* Verify that the remaining claims are valid (e.g., verify that
token has not expired)
* Verify that the "atc" claim "fingerprint" is valid and matches the
account key of the client making the request
* Verify that the "atc" claim "ca" identifier boolean corresponds to
the CA boolean in the Basic Constraints extension in the CSR for
either CA certificate or end-entity certificate
If all steps in the token validation process pass, then the ACME
server MUST set the challenge object "status" to "valid". If any
step of the validation process fails, the "status" in the challenge
object MUST be set to "invalid".
7. Using ACME-issued Certificates with JSON Web Signature
JSON Web Signature (JWS, [RFC7515]) objects can include an "x5u"
header parameter to refer to a certificate that is used to validate
the JWS signature. For example, the STIR PASSporT framework
[RFC8225] uses "x5u" to indicate the STIR certificate used to
validate the PASSporT JWS object. The URLs used in "x5u" are
expected to provide the required certificate in response to a GET
request, not a POST-as-GET as required for the "certificate" URL in
the ACME order object. Thus the current mechanism generally requires
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the ACME client to download the certificate and host it on a public
URL to make it accessible to relying parties. This section defines
an optional mechanism for the Certificate Authority (CA) to host the
certificate directly and provide a URL that the ACME client owner can
directly reference in the "x5u" of their signed PASSporTs.
As described in Section 7.4 of [RFC8555] when the certificate is
ready for making a finalize request, the server will return a 200
(OK) with the updated order object. In this response, an ACME Server
can add a newly defined field called "x5u" that can pass this URL to
the ACME client for usage in generated PASSporTs as a publically
available URL for PASSporT validation.
x5u (optional, string): A URL that can be used to reference the
certificate in the "x5u" parameter of a JWS object [RFC7515]
The publishing of the certificates at the new "x5u" URL should follow
the GET request requirement as mentioned above and should be
consistent with the timely publication according to the durations of
the certificate lifecycle.
The following is an example of the use of "x5u" in the response when
the certificate status is "valid".
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HTTP/1.1 200 OK
Content-Type: application/json
Replay-Nonce: CGf81JWBsq8QyIgPCi9Q9X
Link: <https://example.com/acme/directory>;rel="index"
Location: https://example.com/acme/order/TOlocE8rfgo
{
"status": "valid",
"expires": "2016-01-20T14:09:07.99Z",
"notBefore": "2016-01-01T00:00:00Z",
"notAfter": "2016-01-08T00:00:00Z",
"identifiers": [
"type":"TNAuthList",
"value":"F83n2a...avn27DN3"
],
"authorizations": ["https://sti-ca.com/acme/authz/1234"],
"finalize": "https://example.com/acme/order/TOlocE8rfgo/finalize",
"certificate": "https://example.com/acme/cert/mAt3xBGaobw",
"x5u": "https://example.com/cert-repo/giJI53km23.pem"
}
8. Usage Considerations
8.1. Large number of Non-contiguous TNAuthList values
There are many scenarios and reasons to have various combinations of
SPCs, TNs, and TN Ranges. [RFC8226] has provided a somewhat
unbounded set of combinations. It's possible that a complex non-
contiguous set of telephone numbers are being managed by a CSP. Best
practice may be simply to split a set of non-contiguous numbers under
management into multiple STI certificates to represent the various
contiguous parts of the greater non-contiguous set of TNs,
particularly if length of the set of values in identifier object
grows to be too large.
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9. Security Considerations
The token represented by this document has the credentials to
represent the scope of a telephone number, a block of telephone
numbers, or an entire set of telephone numbers represented by an SPC.
The creation, transport, and any storage of this token MUST follow
the strictest of security best practices beyond the recommendations
of the use of encrypted transport protocols in this document to
protect it from getting in the hands of bad actors with illegitimate
intent to impersonate telephone numbers.
This document inherits the security properties of
[I-D.ietf-acme-authority-token]. Implementations should follow the
best practices identified in [RFC8725].
This document only specifies SHA256 for the fingerprint hash.
However, the syntax of the fingerprint object would permit other
algorithms if, due to concerns about algorithmic agility, a more
robust algorithm were required at a future time. Future
specifications can define new algorithms for the fingerprint object
as needed.
10. IANA Considerations
This document requests the addition of a new identifier object type
to the "ACME Identifier Types" registry defined in Section 9.7.7 of
[RFC8555].
+------------+-----------+
| Label | Reference |
+------------+-----------+
| TNAuthList | RFCThis |
+------------+-----------+
11. Acknowledgements
We would like to thank Richard Barnes and Russ Housley for valuable
contributions to this document.
12. References
12.1. Normative References
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[I-D.ietf-acme-authority-token]
Peterson, J., Barnes, M., Hancock, D., and C. Wendt, "ACME
Challenges Using an Authority Token", Work in Progress,
Internet-Draft, draft-ietf-acme-authority-token-09, 24
October 2022, <https://www.ietf.org/archive/id/draft-ietf-
acme-authority-token-09.txt>.
[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>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[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>.
[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>.
[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>.
[RFC8555] Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
Kasten, "Automatic Certificate Management Environment
(ACME)", RFC 8555, DOI 10.17487/RFC8555, March 2019,
<https://www.rfc-editor.org/info/rfc8555>.
[RFC8725] Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
Current Practices", BCP 225, RFC 8725,
DOI 10.17487/RFC8725, February 2020,
<https://www.rfc-editor.org/info/rfc8725>.
Wendt, et al. Expires 11 August 2023 [Page 15]
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[RFC9060] Peterson, J., "Secure Telephone Identity Revisited (STIR)
Certificate Delegation", RFC 9060, DOI 10.17487/RFC9060,
September 2021, <https://www.rfc-editor.org/info/rfc9060>.
12.2. Informative References
[ATIS-1000080]
ATIS/SIP Forum NNI Task Group, "Signature-based Handling
of Asserted information using toKENs (SHAKEN) Governance
Model and Certificate Management
<https://access.atis.org/apps/group_public/
download.php/32237/ATIS-1000080.pdf>", July 2017.
[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>.
[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>.
Authors' Addresses
Chris Wendt
Somos Inc.
United States of America
Email: chris-ietf@chriswendt.net
David Hancock
Comcast
United States of America
Email: davidhancock.ietf@gmail.com
Mary Barnes
Neustar Inc.
United States of America
Email: mary.ietf.barnes@gmail.com
Wendt, et al. Expires 11 August 2023 [Page 16]
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Jon Peterson
Neustar Inc.
1800 Sutter St Suite 570
Concord, CA 94520,
United States of America
Email: jon.peterson@neustar.biz
Wendt, et al. Expires 11 August 2023 [Page 17]
