Glossary

CSPRNG

Cryptographically secure pseudorandom number generator

Its output cannot feasibly be predicted, even by someone who has seen earlier output, so it is the source for keys, nonces, salts, session IDs and reset tokens. Use the operating system’s generator through APIs such as Python’s secrets module or crypto.getRandomValues, never Math.random or a general-purpose random module.

Also called: cryptographically secure random number generator
Defined in: NIST SP 800-90A Rev. 1, Deterministic Random Bit Generators

Covered in

Reference

Choose cryptographic algorithms and parameters by job

A sourced quick reference for October 2026: which algorithm and parameters to use for encryption, hashing, passwords, MACs, signatures, key agreement, key derivation, randomness and TLS, the matching APIs in Node.js, Python, Java, Go and .NET, and where post-quantum migration stands.

Practice: Insecure randomness lab: Generate unguessable API keys