from
The Free On-line Dictionary of Computing (8 July 2008)
one-way hash function
message digest function
<algorithm> (Or "message digest function") A {one-way
function} 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
(ftp://src.doc.ic.ac.uk/usenet/usenet-by-group/sci.crypt/).
(2001-05-10)