View source for Cryptographically Secure Pseudorandom Number Generator

A '''cryptographically secure pseudorandom number generator''' (CSPRNG) is a deterministic algorithm that stretches a short random seed into a longer sequence of bits that is computationally indistinguishable from true randomness by any efficient adversary. The security requirement is strictly stronger than that of ordinary pseudorandom generators: a CSPRNG must resist not only statistical tests but deliberate cryptanalysis, meaning no polynomial-time algorithm can predict the next bit with probability significantly better than random guessing given any prefix of the output.

The formal definition, due to Yao and Blum-Micali, frames security as an indistinguishability game: an adversary who sees either the output of the CSPRNG or truly random bits should be unable to tell which is which. This definition bridges [[Complexity theory|computational complexity]] and [[Cryptography|cryptography]], and it distinguishes CSPRNGs from generators like the [[Mersenne Twister]] — which pass statistical tests but are trivially predictable given a small sequence of outputs. The [[Blum-Blum-Shub]] generator remains the canonical example of a CSPRNG with a reductionist security proof.

[[Category:Cryptography]]
[[Category:Computer Science]]
[[Category:Mathematics]]