one-way hash function

algorithm (Or "message digest function") A one-wayfunction which takes a variable-length message and produces a

fixed-length hash. Given the hash it is computationally

infeasible to find a message with that hash; in fact one can't

determine any usable information about a message with that

hash, not even a single bit. For some one-way hash functions

it's also computationally impossible to determine two messages

which produce the same hash.

A one-way hash function can be private or public, just like an

encryption function. MD5, SHA and Snefru are examples of

public one-way hash functions.

A public one-way hash function can be used to speed up a

public-key digital signature system. Rather than sign a

long message, which can take a long time, compute the one-way

hash of the message, and sign the hash.

sci.crypt FAQ.

(2001-05-10)