"But there was an utterly trivial fix that DES users could employ if they were worried about security: they could simply encrypt each message twice, turning 56-bit DES into 112-bit DES, and squaring the number of key sequences that a code breaker would have to try. Messages could even be encrypted thrice; and, indeed, many financial institutions at the time were already using "Triple DES." "
Not quite true. Encrypting each message twice would not increase the "effective" key size to 112 bits. There is an attack named "meet in the middle" which will make the effective key size to be just 63 bits. This is why twice was not used and they are using Triple DES, which has an effective key size of 112 bits. Marius Corbu --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]