[jose] Inconsistent use of Key Encryption and Wrapping terms across JWE and JWA?
Brian Campbell <bcampbell@pingidentity.com> Tue, 30 July 2013 15:31 UTC
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From: Brian Campbell <bcampbell@pingidentity.com>
Date: Tue, 30 Jul 2013 17:30:41 +0200
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Subject: [jose] Inconsistent use of Key Encryption and Wrapping terms across JWE and JWA?
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JOSE, The Terminology section in JWE defines Key Encryption and Key Wrapping with the only difference between the two being the type of key (asymmetric vs. symmetric respectively) that is used to encrypt the CEK. Here's the text from JWE §2 [1]: "Key Encryption A Key Management Mode in which the Content Encryption Key (CEK) value is encrypted to the intended recipient using an asymmetric encryption algorithm. Key Wrapping A Key Management Mode in which the Content Encryption Key (CEK) value is encrypted to the intended recipient using a symmetric key wrapping algorithm." However, JWA seems inconsistent in its use of those terms when it talks about about "Key Encryption" with AES GCM [2] and PBES [3], which are symmetric and thus should be "Key Wrapping" based on the definitions above from JWE. Or am I missing something here? Are JWE's definitions of Key Encryption and Key Wrapping consistent with how the world at large would use and understand the terms? I wasn't familiar with the distinction myself. And a little web searching wasn't too conclusive - it looks like XML ENC uses "Key Transport" [4] and "Symmetric Key Wrap" [5] as does CMS [6] while Wikipedia (yeah, I went there) seems to like "Key Encapsulation" [7] and "Key Wrap" [8]. Not that the terms really matter all that much but I've been having a hard time naming things in my implementation and my confusion here isn't helping. Thanks, Brian [1] http://tools.ietf.org/html/draft-ietf-jose-json-web-encryption-14#section-2 [2] http://tools.ietf.org/html/draft-ietf-jose-json-web-algorithms-14#section-4.8 [3] http://tools.ietf.org/html/draft-ietf-jose-json-web-algorithms-14#section-4.9 [4] http://www.w3.org/TR/xmlenc-core/#sec-Alg-KeyTransport [5] http://www.w3.org/TR/xmlenc-core/#sec-Alg-SymmetricKeyWrap [6] http://tools.ietf.org/html/rfc6033 [7] http://en.wikipedia.org/wiki/Key_encapsulation [8] http://en.wikipedia.org/wiki/Key_Wrap
- [jose] Inconsistent use of Key Encryption and Wra… Brian Campbell