My understanding of how an exhaustive search on the key space can be used to break DES is that for every key, K, D(K,Cipher) is applied until the output matches something legible. Say that some random string, to be thrown out, is added to the beginning of the plain text, and that DES is applied in cbc mode, then how could such an attack work? My point, I don't see how DES can be broken if the initial block is a grabage block, and cipher block chaining is used. Please enlighten me (gently). One other point... is the decision to encrypt - decrypt -encrypt when applying triple des arbitrary? Why not just encrypt with k1 and then encrypt with k2. Isn't the effect the same? Thanks a lot, Wonderer ------------------------------------------------------------------------- To find out more about the anon service, send mail to help@anon.penet.fi. Due to the double-blind, any mail replies to this message will be anonymized, and an anonymous id will be allocated automatically. You have been warned. Please report any problems, inappropriate use etc. to admin@anon.penet.fi.