Proxy re-encryption: Difference between revisions

Revision as of 14:11, 8 April 2010

Revision as of 20:37, 15 January 2011

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{{Orphan|date=February 2009}}

'''Proxy re-encryption''' schemes are [[cryptosystems]] which allow third-parties ([[proxy server|proxies]]) to alter a [[ciphertext]] which has been [[encryption|encrypted]] for one party, so that it may be decrypted by another.

==Examples of Use==

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Proxy re-encryption schemes are similar to traditional [[symmetric]] or [[asymmetric]] encryption schemes, with the addition of two functions:

*'''Delegation''' - allows a message recipient (keyholder) to generate a re-encryption key based on his secret key and the key of the delegated user. This re-encryption key is used by the proxy as input to the re-encryption function, which is executed by the proxy to translate ciphertexts to the delegated user's key. Asymmetric proxy re-encryption schemes come in bi-directional and uni-directional varieties.

**In a ''bi-directional scheme'', the re-encryption scheme is reversible-- thatreversible—that is, the re-encryption key can be used to translate messages from Bob to Charlie, as well as from Charlie to Bob. This can have various security consequences, depending on the application. One notable characteristic of bi-directional schemes is that both the delegator and delegated party (e.g., Charlie and Bob) must combine their secret keys to produce the re-encryption key.

**A ''uni-directional scheme'' is effectively one-way; messages can be re-encrypted from Bob to Charlie, but not the reverse. Uni-directional schemes can be constructed such that the delegated party need not reveal its secret key. For example, Bob could delegate to Charlie by combining his secret key with Charlie's public key.

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{{reflist}}

* M. Blaze, G. Bleumer, M. Strauss. [http://link.springer.de/link/service/series/0558/bibs/1403/14030127.htm Divertible Protocols and Atomic Proxy Cryptography].

*Bertino, E., Sandhu, R. [http://ieeexplore.ieee.org/search/wrapper.jsp?arnumber=1416861 "Database security - concepts, approaches, and challenges."] <u>''IEEE TransationsTransactions on Dependable and Secure Computing</u>'' 2 (2005): 2-19

*G. Ateniese, K. Fu, M. Green, S. Hohenberger. [http://spar.isi.jhu.edu/~mgreen/proxy.pdf Improved Proxy Re-encryption Schemes with Applications to Secure Distributed Storage]. Proceedings of the 12th Annual Network and Distributed Systems Security Symposium (NDSS 2005), San Diego, California, 2005.

*M. Green, G. Ateniese. [http://eprint.iacr.org/2006/473 Identity-Based Proxy Re-encryption]. Applied Cryptography and Network Security Conference, June 2007.

*S. Hohenberger, G. Rothblum, a. shelat, and V. Vaikuntanathan. Securely Obfuscating Re-encryption. Proceedings of the Theory of Cryptography Conference (TCC), 2007.

*[http://spar.isi.jhu.edu/~mgreen/prl/ The JHU-MIT Proxy Re-cryptography Library]