Matthew Ghio writes:
When using DES to encrypt email addresses, the total amount of data to be encrypted would be only 3 or 4 eight-byte DES blocks. My question is: Would CBC or CFB really be effective for such a small amount of data
Assuming you're using a random initialization vector rather than zeros, yes, CBC or CFB should be quite effective - the first real block is essentially XORed with random junk, though of course if they guess the right key they can check that the block comes out reasonably. But it does prevent a brute-force attack where they decrypt and see if they get ASCII, since they first block is random junk - they're forced to decrypt at least two blocks of data, which is somewhat annoying for brute-force-search machines. Bill