Glossary of Security Terms: Cryptographic Hash Function

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A cryptographic hash function is a cryptographic primitive transforming a message of arbitrary size into a fixed message of fixed size, called a digest. Hash functions are used for authentication, digital signatures, and message authentication codes. They must have these qualities: They are quick to compute (because they are generated frequently) Not invertible (only brute-force can generate a message that leads to a given digest) tamper-resistant (any change to a message leads to different digest) Collision resistant (it should be impossible to find two different messages that produce the same digest)