Cryptographic hash function
From Wikipedia, the free encyclopedia.

A cryptographic hash function is a hash function which has the following properties,

• Preimage resistant

  Given h such that h=hash(m1) it should be hard to find m1.

• Second preimage resistant

  Given h and m1 such that h=hash(m1) it should be hard to find m1.

• Collision-free

  It should be very hard to find two messages m1 and m2 such that hash(m1)=hash(m2). Because of the birthday paradox this means the hash function has to have a larger image than is required by being preimage-resistant.

See also: Topics in cryptography, cryptography, hash function.

The original article can be found at: http://en.wikipedia.org/wiki/Cryptographic_hash_function.
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