17 Dec
2003
17 Dec
'03
11:17 p.m.
Mike Duvos writes:
frantz@netcom.com (Bill Frantz) writes:
Most cryptographic experts recommend Triple DES, encrypting the data 3 times with 3 different keys.
It's actually encrypted three times with two keys comprising 112 bits of keyspace, using a decrypt on one key sandwiched between two encrypts using the other. This prevents a "man in the middle" attack, which would be possible if only two DES encryptions were used, one for each key.
Many 3DES implementations actually do use 3 different keys. Surprisingly, the strength of 3DES with 3 keys is around the strength you would naively expect 3DES with 2 keys to have, and 3DES with 2 keys is slightly weaker than you would expect... .pm