Identity-based encryption: Difference between revisions

Revision as of 18:59, 12 August 2006

Revision as of 01:03, 9 September 2006

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==Encryption schemes==

The most efficient identity-based encryption schemes are currently based on [[bilinear pairings]] on [[elliptic curves]], such as the [[weil pairing|Weil]] or [[Tate pairing|Tate]] pairings. The first of these schemes was developed by [[Dan Boneh]] and [[Matthew K. Franklin]] ([[2001]]), and performs [[probabilistic encryption]] of arbitrary ciphertexts using an [[Elgamal]]-like approach. Though the Boneh-Franklin scheme is [[Provable security|provably secure]], the security proof rests on relatively new assumptions about the hardness of problems in certain elliptic curve groups. Only limited work has been done in terms of formally analyzing these cryptosystems, some of which have been recently broken (said in 2004).

Another approach to identity-based encryption was proposed by [[Clifford Cocks]] in [[2001]]. The [[Cocks IBE scheme]] is based on well-studied assumptions (the [[quadratic residuosity problem|quadratic residuosity assumption]]) but encrypts messages one bit at a time with a high degree of [[ciphertext expansion]]. Thus it is highly inefficient and impractical for sending all but the shortest messages, such as a session key for use with a [[symmetric cipher]].