Internet DRAFT - draft-wendt-acme-authority-token-tnauthlist
draft-wendt-acme-authority-token-tnauthlist
Network Working Group C. Wendt
Internet-Draft D. Hancock
Intended status: Informational Comcast
Expires: September 6, 2018 M. Barnes
iconectiv
J. Peterson
Neustar Inc.
March 05, 2018
TNAuthList profile of ACME Authority Token
draft-wendt-acme-authority-token-tnauthlist-00
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.
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This Internet-Draft will expire on September 6, 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
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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. ACME new-order identifiers for TNAuthList . . . . . . . . . . 3
4. TNAuthList Identifier Authorization . . . . . . . . . . . . . 4
5. TNAuthList Authority Token . . . . . . . . . . . . . . . . . 6
5.1. "iss" claim . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. "exp" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.3. "jti" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.4. "atc" claim . . . . . . . . . . . . . . . . . . . . . . . 7
5.5. Acquiring the token from the Authority . . . . . . . . . 7
6. Validating the TNAuthList Authority Token . . . . . . . . . . 7
7. Example TNAuthList Tokens . . . . . . . . . . . . . . . . . . 8
7.1. Example-1 . . . . . . . . . . . . . . . . . . . . . . . . 8
7.2. Example-2 . . . . . . . . . . . . . . . . . . . . . . . . 8
7.3. Example-3 . . . . . . . . . . . . . . . . . . . . . . . . 9
8. Large number of Non-contiguous TNAuthList values . . . . . . 9
9. Security Considerations . . . . . . . . . . . . . . . . . . . 10
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
11.1. Normative References . . . . . . . . . . . . . . . . . . 10
11.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
[I-D.ietf-acme-acme] 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.peterson-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 Authority beyond the
Certification Authority.
This document 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.
These credentials are used to sign PASSporTs [RFC8225], which can be
carried in using protocols such as SIP [RFC8224]. Currently, the
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only defined credentials for this purpose are the certificates
specified in [RFC8226].
[RFC8226] describes certificate extensions suitable for associating
telephone numbers and service provider codes with certificates.
Specifically, the TN Authorization List defined in [RFC8226]
Section 9, defines the ability to associate a STI certificate with a
specific set of Service Provider Codes (SPC), Telephone Numbers
(TNs), or Telephone Number ranges (TN ranges). Typically, these
identifiers have been associated to a Communications Service Provider
(CSP) that is authorized to use a set of telephone numbers or
telephone number ranges in association with a Service Provider Code
as defined in [RFC8226]. The SPC is a unique code or string managed
by a national regulatory body that has the authority over those code
associations.
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 [RFC2119].
3. ACME new-order identifiers for TNAuthList
In [I-D.ietf-acme-acme], Section 7.4 defines the procedure that an
ACME client uses to order a new certificate from a Certificate
Authority. The new-order request contains an identifier object that
specifies the identifiers the order corresponds to. For the
TNAuthList identifier, the new-order request MUST include a type set
to the string "TNAuthList". The value of the identifier MUST be set
to the details of the TNAuthList requested.
The format of the string that represents the TNAuthList MUST be
constructed as follows. The TNAuthList as defined in [RFC8226] can
include three types of identifiers.
1. Service Provider Code (SPC) identified as "spc"
2. Telephone Number (TN) identified as "tn"
3. Telephone Number Range (TNRange) identified as "tnrange"
The above types of identifiers and the corresponding strings should
be used as a JSON key part of an array of JSON key and value pairs.
The JSON value would be the string representing the corresponding
SPC, TN, or TNRange values.
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For example, a request for a TNAuthList certificate with a SPC value
of "1234" and a TN value of "2155551212" would look as follows,
"identifiers": [{"type":"TNAuthList","value":"["spc":"1234",
"tn","2155551212"]"}]
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/1",
"nonce": "5XJ1L3lEkMG7tR6pA00clA",
"url": "https://example.com/acme/new-order"
}),
"payload": base64url({
"identifiers": [{"type:"TNAuthList","value":"["spc":"1234",
"tn":"2155551212"]"}],
"notBefore": "2016-01-01T00:00:00Z",
"notAfter": "2016-01-08T00:00:00Z"
}),
"signature": "H6ZXtGjTZyUnPeKn...wEA4TklBdh3e454g"
}
4. TNAuthList Identifier Authorization
On receiving a valid new-order request, the CA creates an
authorization challenge and can be queried by the following example
request and response.
GET /acme/authz/1234 HTTP/1.1
Host: example.com
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HTTP/1.1 200 OK
Content-Type: application/json
Link: <https://example.com/acme/some-directory>;rel="index"
{
"status": "pending",
"expires": "2018-03-03T14:09:00Z",
"identifier": {
"type:"TNAuthList",
"value":"["spc":"1234","tn":"2155551212"]"
},
"challenges": [
{
"type": "tkauth-01",
"tkauth-type": "ATC",
"token-authority": "https://authority.example.org/authz",
"url": "https://boulder.example.com/authz/asdf/0"
"token": "IlirfxKKXAsHtmzK29Pj8A"
}
]
}
This follows [I-D.peterson-acme-authority-token] with a specific
identifier corresponding to the specific challenge as defined
previously in this document.
When processing a certificate order containing an identifier of type
"TNAuthList", a CA MUST use the Authority Token challenge mechanism
defined in [I-D.peterson-acme-authority-token] to verify that the
requesting ACME client has control over the requested "TNAuthList"
value.
The challenge "token-authority" parameter is optional and only used
in cases where the VoIP telephone network requires a CA to determine
the 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 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
Authority based on locally configured information or local policies.
A client responds to this challenge by providing an TNAuthList
Authority Token to the CA. The ACME client MUST respond to the
challenge by posting the TNAuthList Authority Token to the URL
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identified in the ACME challenge with a request, an example of which
follows.
POST /acme/authz/asdf/0 HTTP/1.1
Host: sti-ca.com
Content-Type: application/jose+json
{
"protected": base64url({
"alg": "ES256",
"kid": "https://sti-ca.com/acme/reg/asdf",
"nonce": "Q_s3MWoqT05TrdkM2MTDcw",
"url": "https://sti-ca.com/acme/authz/asdf/0"
}),
"payload": base64url({
"ATC": "DGyRejmCefe7v4N...vb29HhjjLPSggwiE"
}),
"signature": "9cbg5JO1Gf5YLjjz...SpkUfcdPai9uVYYQ"
}
The specifics of the construction of the "ATC" token is defined in
the next section.
5. TNAuthList Authority Token
The Telephone Number Authority List Authority Token (TNAuthList
Authority Token) is an extension of the ACME Authority Token defined
in [I-D.peterson-acme-authority-token].
The TNAuthList Authority Token Protected header MUST comply with the
Authority Token Protected header as defined in
[I-D.peterson-acme-authority-token].
The TNAuthList Authority Token Payload MUST include the claims
defined for the Authority Token. These are detailed in the next
subsections.
5.1. "iss" claim
The "iss" claim is an optional claim. It can be used as a URL
identifying the Authority that issued the TNAuthList Authority Token
beyond the "x5u" Header claim that identifies the location of the
certificate of the Authority used to validate the Authority Token.
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5.2. "exp" claim
The "exp" claim contains the DateTime value of the ending time and
date that the TNAuthList Authority Token expires.
5.3. "jti" claim
The "jti" claim contains a unique identifier for the TNAuthList
Authority Token transaction.
5.4. "atc" claim
The "atc" claim is the only claim specifically defined in this
document. It contains an array of three elements; a string set to
"TNAuthList", an identifier value which is an array of the
identifiers to be included in the TNAuthList of the requesting SP,
and a nonce.
An example of the TNAuthList Authority Token is as follows,
{ "typ":"JWT",
"alg":"ES256",
"x5u":https://authority.example.org/cert
}
{
"iss":"https://authority.example.org/authz",
"exp":1300819380,
"jti":"id6098364921",
"atc":["TnAuthList","["spc":"1234","tn":"2155551212"]",
"Q_s3MWoqT05TrdkM2MTDcw"]
}
Similar to how the TNAuthList identifier value is defined, the
identifier value in the "atc" should also include the same JSON array
of TNAuthList values with key/value pairs representing each part of
the TNAuthList.
5.5. Acquiring the token from the Authority
The specifics of how the token is acquired from the authority is out
of the scope of this document.
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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o Verify that the token contained in the Payload "ATC" field is an
TNAuthList Authority Token.
o Verify the TNAuthList Authority Token signature using the public
key of the certificate referenced by the token's "x5u" parameter.
o Verify that "atc" claim contains an identifier type of
"TNAuthList",
o Verify that the "atc" claim contains keys and values that matches
the keys and values of the Identifier specified in the original
challenge.
o Verify that the remaining claims are valid (e.g., verify that
token has not expired)
If all steps in the token validation process pass, then the CA 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. Example TNAuthList Tokens
This section provides some TNAuthList Authority Token examples.
7.1. Example-1
TNAuthList Authority Token authorizing a TNAuthList containing a
single SPC value
{
"typ":"JWT",
"alg":"ES256",
"x5u":https://authority.example.org/cert
}
{
"iss":"https://authority.example.org/authz",
"exp":1300819380,
"jti":"id6098364921",
"atc":["TnAuthList","["spc":"1234"]","Q_s3MWoqT05TrdkM2MTDcw"]
}
7.2. Example-2
TNAuthList Authority Token authorizing a TNAuthList identifier
containing an SPC value plus a range of TNs
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{
"typ":"JWT",
"alg":"ES256",
"x5u":https://authority.example.org/cert
}
{
"iss":"https://authority.example.org/authz",
"exp":1300819380,
"jti":"id6098364921",
"atc":["TnAuthList",
["spc":"1234","tn-range":{"start":"12155551212","count":"50"}],
"Q_s3MWoqT05TrdkM2MTDcw"]
}
7.3. Example-3
TNAuthList Authority Token authorizing a TNAuthList identifier
containing a single TN
{
"typ":"JWT",
"alg":"ES256",
"x5u":https://authority.example.org/cert
}
{
"iss":"https://authority.example.org/authz",
"exp":1300819380,
"jti":"id6098364921",
"atc":["TnAuthList",
["tn":"12155551212"],
"Q_s3MWoqT05TrdkM2MTDcw"]
}
8. 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
TBD
10. Acknowledgements
We would like to thank you for your review of this document.
11. References
11.1. Normative References
[I-D.ietf-acme-acme]
Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
Kasten, "Automatic Certificate Management Environment
(ACME)", draft-ietf-acme-acme-09 (work in progress),
December 2017.
[I-D.peterson-acme-authority-token]
Peterson, J., "ACME Challenges Using an Authority Token",
draft-peterson-acme-authority-token-00 (work in progress),
October 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>.
[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>.
11.2. Informative References
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[ATIS-1000074]
ATIS/SIP Forum NNI Task Group, "Signature-based Handling
of Asserted information using toKENs (SHAKEN)", January
2017.
[ATIS-1000080]
ATIS/SIP Forum NNI Task Group, "Signature-based Handling
of Asserted information using toKENs (SHAKEN) Governance
Model and Certificate Management", July 2017.
[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>.
Authors' Addresses
Chris Wendt
Comcast
One Comcast Center
Philadelphia, PA 19103
USA
Email: chris-ietf@chriswendt.net
David Hancock
Comcast
Email: davidhancock.ietf@gmail.com
Mary Barnes
iconectiv
Email: mary.ietf.barnes@gmail.com
Jon Peterson
Neustar Inc.
1800 Sutter St Suite 570
Concord, CA 94520
US
Email: jon.peterson@neustar.biz
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