Message Encryption for Web Push
RFC 8291
Internet Engineering Task Force (IETF) M. Thomson
Request for Comments: 8291 Mozilla
Category: Standards Track November 2017
ISSN: 2070-1721
Message Encryption for Web Push
Abstract
This document describes a message encryption scheme for the Web Push
protocol. This scheme provides confidentiality and integrity for
messages sent from an application server to a user agent.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
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/rfc8291.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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described in the Simplified BSD License.
Thomson Standards Track [Page 1]
RFC 8291 Web Push Encryption November 2017
Table of Contents
1. Introduction ....................................................2
1.1. Notational Conventions .....................................3
2. Push Message Encryption Overview ................................3
2.1. Key and Secret Distribution ................................4
3. Push Message Encryption .........................................4
3.1. Diffie-Hellman Key Agreement ...............................5
3.2. Push Message Authentication ................................5
3.3. Combining Shared and Authentication Secrets ................5
3.4. Encryption Summary .........................................6
4. Restrictions on Use of "aes128gcm" Content Coding ...............7
5. Push Message Encryption Example .................................8
6. IANA Considerations .............................................8
7. Security Considerations .........................................8
8. References .....................................................10
8.1. Normative References ......................................10
8.2. Informative References ....................................11
Appendix A. Intermediate Values for Encryption ...................12
Author's Address ..................................................13
1. Introduction
The Web Push protocol [RFC8030] is an intermediated protocol by
necessity. Messages from an application server are delivered to a
user agent (UA) via a push service, as shown in Figure 1.
+-------+ +--------------+ +-------------+
| UA | | Push Service | | Application |
+-------+ +--------------+ +-------------+
| | |
| Setup | |
|<====================>| |
| Provide Subscription |
|-------------------------------------------->|
| | |
: : :
| | Push Message |
| Push Message |<---------------------|
|<---------------------| |
| | |
Figure 1
This document describes how messages sent using this protocol can be
secured against inspection, modification, and forgery by a push
service.
Thomson Standards Track [Page 2]
RFC 8291 Web Push Encryption November 2017
Web Push messages are the payload of an HTTP message [RFC7230].
These messages are encrypted using an encrypted content encoding
[RFC8188]. This document describes how this content encoding is
applied and describes a recommended key management scheme.
Multiple users of Web Push at the same user agent often share a
central agent that aggregates push functionality. This agent can
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