On 6/13/07, Dinesh Joshi <[EMAIL PROTECTED]> wrote:
Get your facts straight before you reply. a message encrypted with a 128 bit key DES is no more secure than a 64 bit key DES. Actually the length of the key is only 56 bit in the latter case.
Please cite a source for this. I'd like to know how DES is done with a 128 bit key. The Data Encryption Standard (DES) implies the use of a 56 bit key. Change the key length and you'll have to change multiple parameters of the algorithm. For example, with a 56 bit key, the algorithm works on 64 bits of data at a time. This chunk definition, substituter blocks and permutation blocks will all have to change, hence changing the very nature of the algorithm. You will hence have to end up with a DES-like algorithm rather than the DES algorithm, albeit with a larger key size. Difficulty in brute forcing a crypt is then just a function of the key size -- more the bits, more difficult it is. Here's apparently the first case of DES being broken by brute force: http://www.interhack.net/pubs/des-key-crack/ PS: I'm not a crypto expert, I'm just trying to reason out stuff based on facts I read up. Please correct wherever applicable. -- Siddhesh Poyarekar This document validates as Plain Text -- http://mm.glug-bom.org/mailman/listinfo/linuxers
