Internet DRAFT - draft-jones-jose-aes-gcm-key-wrap
draft-jones-jose-aes-gcm-key-wrap
JOSE Working Group M. Jones
Internet-Draft Microsoft
Intended status: Standards Track July 14, 2013
Expires: January 15, 2014
Key Wrapping with AES GCM for JWE
draft-jones-jose-aes-gcm-key-wrap-01
Abstract
This specification defines how to encrypt (wrap) keys with the AES
GCM algorithm for JSON Web Encryption (JWE) objects.
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This Internet-Draft will expire on January 15, 2014.
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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
3.1. Header Parameters Used for AES GCM Key Encryption . . . . . 4
3.1.1. "iv" (Initialization Vector) Header Parameter . . . . . 4
3.1.2. "tag" (Authentication Tag) Header Parameter . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
4.1. JSON Web Signature and Encryption Algorithms
Registration . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.1. Registry Contents . . . . . . . . . . . . . . . . . . . 4
4.2. Registration of JWE Header Parameter Names . . . . . . . . 4
4.2.1. Registry Contents . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
6. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Appendix A. Document History . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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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 Initialization Vector is represented in base64url
encoded form as the "iv" (initialization vector) header parameter
value.
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.
The JWE Encrypted Key value is the Ciphertext output.
The Authentication Tag output is represented in base64url encoded
form as the "tag" (authentication tag) header parameter value.
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3.1. Header Parameters Used for AES GCM Key Encryption
The following Header Parameter Names are used for AES GCM key
encryption. They MAY also be used by other algorithms if so
specified by those algorithm parameter definitions.
3.1.1. "iv" (Initialization Vector) Header Parameter
The "iv" (initialization vector) header parameter value is the
base64url encoded representation of the Initialization Vector value
used for the key encryption operation. This Header Parameter is
REQUIRED and MUST be understood and processed by implementations when
these algorithms are used.
3.1.2. "tag" (Authentication Tag) Header Parameter
The "tag" (authentication tag) header parameter value is the
base64url encoded representation of the Authentication Tag value
resulting from the key encryption operation. This Header Parameter
is REQUIRED and MUST be understood and processed by implementations
when these algorithms are used.
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 ]]
4.2. Registration of JWE Header Parameter Names
This specification registers the Header Parameter Names defined in
Section 3.1 in the IANA JSON Web Signature and Encryption Header
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Parameters registry [JWS].
4.2.1. Registry Contents
o Header Parameter Name: "iv"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 3.1.1 of [[ this document ]]
o Header Parameter Name: "tag"
o Header Parameter Usage Location(s): JWE
o Change Controller: IETF
o Specification Document(s): Section 3.1.2 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),
July 2013.
[JWE] Jones, M., Rescorla, E., and J. Hildebrand, "JSON Web
Encryption (JWE)", draft-ietf-jose-json-web-encryption
(work in progress), July 2013.
[JWS] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", draft-ietf-jose-json-web-signature (work
in progress), July 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.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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Appendix A. Document History
[[ to be removed by the RFC editor before publication as an RFC ]]
-01
o Represented Initialization Vector and Authentication Tag values
used as header parameter values so as to be more parallel with
their treatment when using AES GCM for content encryption, per
working group request.
-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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