Jack Lloyd wrote: > On Mon, Dec 12, 2005 at 12:20:26AM -0600, Travis H. wrote: >> 2) While CTR mode with a random key is sufficient for creating a >> permutation of N-bit blocks for a fixed N, is there a general-purpose >> way to create a N-bit permutation, where N is a variable? How about >> picking a cryptographically strong permutation on N elements, where N >> is not necessarily a power of 2? > > Use can use the Bear or Lion constructions to form 2^{arbitrary} bit block > ciphers quite easily.
Good ciphers aren't permutations, though, are they? Because if they were, they'd be groups, and that would be bad. -- http://www.apache-ssl.org/ben.html http://www.thebunker.net/ ** ApacheCon - Dec 10-14th - San Diego - http://apachecon.com/ ** "There is no limit to what a man can do or how far he can go if he doesn't mind who gets the credit." - Robert Woodruff --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]