Object Security for Constrained RESTful Environments (OSCORE)
RFC 8613
Internet Engineering Task Force (IETF) G. Selander
Request for Comments: 8613 J. Mattsson
Updates: 7252 F. Palombini
Category: Standards Track Ericsson AB
ISSN: 2070-1721 L. Seitz
RISE
July 2019
Object Security for Constrained RESTful Environments (OSCORE)
Abstract
This document defines Object Security for Constrained RESTful
Environments (OSCORE), a method for application-layer protection of
the Constrained Application Protocol (CoAP), using CBOR Object
Signing and Encryption (COSE). OSCORE provides end-to-end protection
between endpoints communicating using CoAP or CoAP-mappable HTTP.
OSCORE is designed for constrained nodes and networks supporting a
range of proxy operations, including translation between different
transport protocols.
Although an optional functionality of CoAP, OSCORE alters CoAP
options processing and IANA registration. Therefore, this document
updates RFC 7252.
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/rfc8613.
Selander, et al. Standards Track [Page 1]
RFC 8613 OSCORE July 2019
Copyright Notice
Copyright (c) 2019 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 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.
Selander, et al. Standards Track [Page 2]
RFC 8613 OSCORE July 2019
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7
2. The OSCORE Option . . . . . . . . . . . . . . . . . . . . . . 8
3. The Security Context . . . . . . . . . . . . . . . . . . . . 8
3.1. Security Context Definition . . . . . . . . . . . . . . . 9
3.2. Establishment of Security Context Parameters . . . . . . 11
3.3. Requirements on the Security Context Parameters . . . . . 14
4. Protected Message Fields . . . . . . . . . . . . . . . . . . 15
4.1. CoAP Options . . . . . . . . . . . . . . . . . . . . . . 16
4.2. CoAP Header Fields and Payload . . . . . . . . . . . . . 24
4.3. Signaling Messages . . . . . . . . . . . . . . . . . . . 25
5. The COSE Object . . . . . . . . . . . . . . . . . . . . . . . 26
5.1. ID Context and 'kid context' . . . . . . . . . . . . . . 27
5.2. AEAD Nonce . . . . . . . . . . . . . . . . . . . . . . . 28
5.3. Plaintext . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4. Additional Authenticated Data . . . . . . . . . . . . . . 30
6. OSCORE Header Compression . . . . . . . . . . . . . . . . . . 31
6.1. Encoding of the OSCORE Option Value . . . . . . . . . . . 32
6.2. Encoding of the OSCORE Payload . . . . . . . . . . . . . 33
6.3. Examples of Compressed COSE Objects . . . . . . . . . . . 33
7. Message Binding, Sequence Numbers, Freshness, and Replay
Protection . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.1. Message Binding . . . . . . . . . . . . . . . . . . . . . 36
7.2. Sequence Numbers . . . . . . . . . . . . . . . . . . . . 36
7.3. Freshness . . . . . . . . . . . . . . . . . . . . . . . . 36
7.4. Replay Protection . . . . . . . . . . . . . . . . . . . . 37
7.5. Losing Part of the Context State . . . . . . . . . . . . 38
8. Processing . . . . . . . . . . . . . . . . . . . . . . . . . 39
8.1. Protecting the Request . . . . . . . . . . . . . . . . . 39
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