Cryptographically Secure Pseudo Random Number Generator

A Cryptographically Secure Pseudo Random Number Generator (CSPRNG) is an algorithm that generates pseudo-random numbers suitable for cryptographic applications, ensuring unpredictability and resistance to attacks. It produces sequences that appear random and cannot be feasibly predicted or reproduced by adversaries, even with partial knowledge of previous outputs or internal state. CSPRNGs are essential for security-sensitive operations like key generation, encryption, and authentication.

Also known as: CSPRNG, Cryptographically Secure Random Number Generator, Secure Random Number Generator, Cryptographic RNG, Secure PRNG

Why learn Cryptographically Secure Pseudo Random Number Generator?

Developers should use CSPRNGs when security is critical, such as in generating cryptographic keys, initialization vectors, nonces, or random tokens for sessions and passwords. They are necessary in applications like secure communications (e.g., TLS/SSL), blockchain systems, and password managers to prevent vulnerabilities from predictable randomness. Learning CSPRNGs helps avoid common pitfalls like using non-secure random functions (e.g., standard library rand()) in security contexts.

Learning Resources

• docs: NIST Special Publication 800-90A: Recommendation for Random Number Generation Using Deterministic Random Bit Generators
• docs: OWASP Cryptographic Storage Cheat Sheet - Random Number Generation
• course: Coursera: Cryptography I by Stanford University
• video: YouTube: Introduction to Cryptographically Secure Pseudo-Random Number Generators by Computerphile
• book: Book: Cryptography Engineering by Niels Ferguson, Bruce Schneier, and Tadayoshi Kohno