- • Algorithms that output a unique 'fingerprint' for a given input of data (MDx, SHA1)
- • Input data may be of almost any length
- • No key is required - only data is needed as input (Though an IV can be used in some cases (! PHP))
- • Generated "fingerprint" is of a fixed length
- • Deterministic
- • Considered nigh-impossible to reconstruct the input data given the output data
- • Also called one-way functions, message digests, signatures and hashes
- • Unix, MySQL, htpasswd, ... password systems
- • Hash user credentials together with preference information
- • i.e. md5($user_name, $password, $mark_on_test)
- • Data is not reversible - just comparable
