STIR Out-of-Band Architecture and Use Cases
draft-ietf-stir-oob-07
Network Working Group E. Rescorla
Internet-Draft Mozilla
Intended status: Informational J. Peterson
Expires: September 10, 2020 Neustar
March 9, 2020
STIR Out-of-Band Architecture and Use Cases
draft-ietf-stir-oob-07
Abstract
The PASSporT format defines a token that can be carried by signaling
protocols, including SIP, to cryptographically attest the identify of
callers. Not all telephone calls use Internet signaling protocols,
however, and some calls use them for only part of their signaling
path, or cannot reliably deliver SIP header fields end-to-end. This
document describes use cases that require the delivery of PASSporT
objects outside of the signaling path, and defines architectures and
semantics to provide this functionality.
Status of This Memo
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This Internet-Draft will expire on September 10, 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Operating Environments . . . . . . . . . . . . . . . . . . . 4
4. Dataflows . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.1. Case 1: VoIP to PSTN Call . . . . . . . . . . . . . . . . 7
5.2. Case 2: Two Smart PSTN endpoints . . . . . . . . . . . . 7
5.3. Case 3: PSTN to VoIP Call . . . . . . . . . . . . . . . . 7
5.4. Case 4: Gateway Out-of-band . . . . . . . . . . . . . . . 8
5.5. Case 5: Enterprise Call Center . . . . . . . . . . . . . 9
6. Storing and Retrieving PASSporTs . . . . . . . . . . . . . . 9
6.1. Storage . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.2. Retrieval . . . . . . . . . . . . . . . . . . . . . . . . 11
7. Solution Architecture . . . . . . . . . . . . . . . . . . . . 12
7.1. Credentials and Phone Numbers . . . . . . . . . . . . . . 12
7.2. Call Flow . . . . . . . . . . . . . . . . . . . . . . . . 13
7.3. Security Analysis . . . . . . . . . . . . . . . . . . . . 13
7.4. Substitution Attacks . . . . . . . . . . . . . . . . . . 14
7.5. Rate Control for CPS Storage . . . . . . . . . . . . . . 16
8. Authentication and Verification Service Behavior for Out-of-
Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Authentication Service (AS) . . . . . . . . . . . . . . . 17
8.2. Verification Service (VS) . . . . . . . . . . . . . . . . 18
8.3. Gateway Placement Services . . . . . . . . . . . . . . . 19
9. Example HTTPS Interface to the CPS . . . . . . . . . . . . . 20
10. CPS Discovery . . . . . . . . . . . . . . . . . . . . . . . . 21
11. Encryption Key Lookup . . . . . . . . . . . . . . . . . . . . 23
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 24
15. Security Considerations . . . . . . . . . . . . . . . . . . . 25
16. Informative References . . . . . . . . . . . . . . . . . . . 26
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