JOSE Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track June 13, 2013
Expires: December 15, 2013
Key Wrapping with AES GCM for JWE
draft-jones-jose-aes-gcm-key-wrap-00
Abstract
This specification defines how to encrypt (wrap) keys with the AES
GCM algorithm for JSON Web Encryption (JWE) objects.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Key Encryption with AES GCM . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
4.1. JSON Web Signature and Encryption Algorithms
Registration . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.1. Registry Contents . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Appendix A. Document History . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
This specification defines how to encrypt (wrap) keys with the AES
GCM algorithm [AES] [NIST.800-38D] for JSON Web Encryption (JWE)
[JWE] objects.
1.1. Notational Conventions
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 Key words for use in
RFCs to Indicate Requirement Levels [RFC2119].
2. Terminology
This specification uses the same terminology as the JSON Web
Encryption (JWE) [JWE] and JSON Web Algorithms (JWA) [JWA]
specifications.
3. Key Encryption with AES GCM
This section defines the specifics of encrypting a JWE Content
Encryption Key (CEK) with Advanced Encryption Standard (AES) in
Galois/Counter Mode (GCM) [AES] [NIST.800-38D] using 128 or 256 bit
keys. The "alg" header parameter values "A128GCMKW" or "A256GCMKW"
are respectively used in this case.
Use of an Initialization Vector of size 96 bits is REQUIRED with this
algorithm.
The Additional Authenticated Data value used is the empty octet
string.
The requested size of the Authentication Tag output MUST be 128 bits,
regardless of the key size.
Let JWE Encrypted Key value be the concatenation of the
Initialization Vector value, the Ciphertext output, and the
Authentication Tag output.
During key decryption, the JWE Encrypted Key value is split into
three inputs to the AES GCM decryption algorithm: the first 96 bits
are the Initialization Vector value, the last 128 bits are the
Authentication Tag value, and the remaining bits in between are the
Ciphertext value.
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4. IANA Considerations
4.1. JSON Web Signature and Encryption Algorithms Registration
This specification registers the algorithms defined in Section 3 in
the JSON Web Signature and Encryption Algorithms registry [JWA].
4.1.1. Registry Contents
o Algorithm Name: "A128GCMKW"
o Algorithm Usage Location(s): "alg"
o Implementation Requirements: OPTIONAL
o Change Controller: IETF
o Specification Document(s): Section 3 of [[ this document ]]
o Algorithm Name: "A256GCMKW"
o Algorithm Usage Location(s): "alg"
o Implementation Requirements: OPTIONAL
o Change Controller: IETF
o Specification Document(s): Section 3 of [[ this document ]]
5. Security Considerations
The security considerations in [AES] and [NIST.800-38D] also apply to
this specification.
6. Normative References
[AES] National Institute of Standards and Technology (NIST),
"Advanced Encryption Standard (AES)", FIPS PUB 197,
November 2001.
[JWA] Jones, M., "JSON Web Algorithms (JWA)",
draft-ietf-jose-json-web-algorithms (work in progress),
May 2013.
[JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
Encryption (JWE)", draft-ietf-jose-json-web-encryption
(work in progress), May 2013.
[NIST.800-38D]
National Institute of Standards and Technology (NIST),
"Recommendation for Block Cipher Modes of Operation:
Galois/Counter Mode (GCM) and GMAC", NIST PUB 800-38D,
December 2001.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Appendix A. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-00
o Created draft-jones-jose-aes-gcm-key-wrap.
Author's Address
Michael B. Jones
Microsoft
Email: mbj@microsoft.com
URI: http://self-issued.info/
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