On Mon, Sep 16, 2013 at 12:44 PM, Bill Frantz <[email protected]> wrote:
> Symmetric encryption: > > Two algorithms give security equal to the best of them. Three > protect against meet-in-the-middle attacks. Performing the > multiple encryption at the block level allows block cyphers to > be combined with stream cyphers. RC4 may have problems, but > adding it to the mix isn't very expensive. A paper of mine on combining a stream cipher with a block cipher: http://eprint.iacr.org/2008/473 AES-256 uses 14 rounds vs. 10 for AES-128, so it is about 40% slower. Given 256 bits of key and a stream cipher that is 5x faster than AES, you can use AES-128 and have 128 bits to key the stream cipher. AES-128 plus whitening that changes for every block (two 128-bit blocks of stream cipher output) has roughly the same cost as AES-256. There are several ways to reduce the cost and/or increase the security from there; see the paper for details. I am still working on this notion and will have a new and much improved version of that paper sometime this year. Anyone I know moderately well who wants to review it can contact me off-list for the current draft. _______________________________________________ The cryptography mailing list [email protected] http://www.metzdowd.com/mailman/listinfo/cryptography
