Early 1970s - Multics: non-cryptographic hashes Attempted one-way transformations, but no "true" cryptographic hashes yet "Multics User Control subsystem stored passwords one-way encrypted [...] I knew people could take square roots, so I squared each password and ANDed with a mask to discard some bits." After successful break by the Air Force tiger team doing a security evaluation of Multics in 1972-1974, "we quickly changed the encryption to a new stronger method" Tom Van Vleck, "How the Air Force cracked Multics Security", 1993 (with later updates)