Problems worthy of attack prove their worth by hitting back. —Piet Hein

Wednesday, 31 October 2007

Mixing with MD5

MD5 and cryptographic hash functions in general have many uses - not least integrity checking and password storage. They have the property of mixing the input in an unpredictable but deterministic way. This can be very useful - and not just in security applications. Here are two great examples I came across recently: partitioning users into groups for controlled experiments on the web, and Dopplr's colour-coding of cities. Neat.

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