A random number generator (RNG) is a device or algorithm that produces sequences of numbers in which each value is unpredictable and equally likely. In probability theory and statistics, RNGs underpin methods for sampling from continuous distributions and modeling stochastic processes.

In cryptography and computer security, high-quality randomness is crucial: it ensures that keys, nonces, and other secret values remain unguessable. A cryptographically secure pseudorandom number generator (CSPRNG) achieves this by producing a bitstream that is computationally indistinguishable from true randomness, even when an adversary knows the algorithm’s design.