Here's the announcement from Google in April last year: http://google-opensource.blogspot.com/2011/04/introducing-cityhash.html http://google-opensource.blogspo

Here's the announcement from Google in April last year: http://google-opensource.blogspot.com/2011/04/introducing-cityhash.html http://google-opensource.blogspot.com/2011/04/introducing-ci... The most important thing to take away from this is "These functions aren’t suitable for cryptography". The requirements for a cryptographically strong hash function are much stronger than one just used for hash-table performance. That's not to say that you shouldn't use it, rather be careful that there's no scope creep.