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This specification defines how to encrypt (wrap) keys with the AES GCM algorithm for JSON Web Encryption (JWE) objects.
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as “work in progress.”
This Internet-Draft will expire on December 15, 2013.
Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved.
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1.
Introduction
1.1.
Notational Conventions
2.
Terminology
3.
Key Encryption with AES GCM
4.
IANA Considerations
4.1.
JSON Web Signature and Encryption Algorithms Registration
4.1.1.
Registry Contents
5.
Security Considerations
6.
Normative References
Appendix A.
Document History
§
Author's Address
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This specification defines how to encrypt (wrap) keys with the AES GCM algorithm [AES] (National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.) [NIST.800‑38D] (National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC,” December 2001.) for JSON Web Encryption (JWE) [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) objects.
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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] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).
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This specification uses the same terminology as the JSON Web Encryption (JWE) [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) and JSON Web Algorithms (JWA) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) specifications.
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This section defines the specifics of encrypting a JWE Content Encryption Key (CEK) with Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) [AES] (National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.) [NIST.800‑38D] (National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC,” December 2001.) 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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This specification registers the algorithms defined in Section 3 (Key Encryption with AES GCM) in the JSON Web Signature and Encryption Algorithms registry [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.).
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The security considerations in [AES] (National Institute of Standards and Technology (NIST), “Advanced Encryption Standard (AES),” November 2001.) and [NIST.800‑38D] (National Institute of Standards and Technology (NIST), “Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC,” December 2001.) also apply to this specification.
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[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 (HTML). |
[JWE] | Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” draft-ietf-jose-json-web-encryption (work in progress), May 2013 (HTML). |
[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 (TXT, HTML, XML). |
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[[ to be removed by the RFC editor before publication as an RFC ]]
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Michael B. Jones | |
Microsoft | |
Email: | mbj@microsoft.com |
URI: | http://self-issued.info/ |