Hello, > On Wed, Oct 18, 2006 at 11:35:13AM +0200, Marek Marcola wrote: > > Hello, > > > the block size is always the same as the key length in AES (and the most > > > block > > > ciphers, I think). You are using 128-AES -> 128 bits key == 16 bytes > > > block size > > > (q.e.d). > > Not exactly: > > > > AES128: block_size: 16 bytes, key_size: 16 bytes > > AES192: block_size: 16 bytes, key_size: 24 bytes > > AES256: block_size: 16 bytes, key_size: 32 bytes > > DES: block_size: 8 bytes, key_size: 8 bytes > > DES3: block_size: 8 bytes, key_size: 24 bytes (3*8 bytes) > > > The way block ciphering works is by first deriving a key schedule from the > key. Different ciphers have different ways of deriving enough entropy for > each of the schedule keys. > > I believe (correct me if I am wrong) that for each round a different key is > used. And this key is one of the keys in the schedule. > > The way the input block interacts with the round key therefore is not a one > to one relationship... > > Sorry my knowledge stops there as things are misty right now. It is close to > 6 years since I took an interest in these things. :-) Yes, I agree. For example in AES128 from 128 bit key (16 bytes) with key expansion algorithm 10 round keys are generated (128 bit long each) for each round. In AES192 there are 12 rounds and 12 round keys (128 bit long too) are generated from 192 bits of input key. And in AES 256 there are 14 rounds with 14 rounds key generated each 128 bit long from 256 bits of input key. In DES, from 64 bit key (8 bytes) 16 round keys are generated each 48 bits long.
Best regards, -- Marek Marcola <[EMAIL PROTECTED]> ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager [EMAIL PROTECTED]
