1: MD5 still provides preimage resistance (both first and second), which is sometimes useful. 2, and my real objection: $ md5sum /dev/null d41d8cd98f00b20

1: MD5 still provides preimage resistance (both first and second), which is sometimes useful. 2, and my real objection: $ md5sum /dev/null d41d8cd98f00b204e9800998ecf8427e /dev/null $ seahashsum /dev/null <stdin>:2:0: seahashsum: command not found That said, my main point was don't use SHA-1, because if you actually need a half-broken hash function for something, MD5 has all the same properties (good and bad) for cheaper.