That is the definition for hash functions. The other commenter was, not to put too fine a point on it, wrong. From Schneier's Self-Study Course in Block-Cipher Cryptanalysis:
"Breaking a cipher simply means finding a weakness in the cipher that can be exploited with a complexity less than brute-force."
But please go on about how you know more than Schneier.
"Breaking a cipher simply means finding a weakness in the cipher that can be exploited with a complexity less than brute-force."
But please go on about how you know more than Schneier.