Although not completely broken, there are enough problems with MD5 to make most cryptographers nervous. SHA1 is a much more robust algorithm, and has a longer hash value to boot. If you happen to be stuck using MD5, there's not much you can do, but do try to use SHA1 whenever possible.

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I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated