Pseudo Random Number Generator

A random number generated from Deterministic Algorithm. A PRF should generate an arbitrary length random value from a given seed. The output should be indistinguishable from random data.

Formal Definition

A PRF is an algorithm that takes in:

• Secret input $i$
• Desired number of bits $n$
• Seed data $s$ Returns an output String $o\in \{0,1{\}}^{\ast }$

Implementations

Linear Recursion

• LCG
• Mersenne Twister
• xorshift
• Well Equidistributed Long-period LInear

Counter-Based

$\text{output}=f(n,key)$

• Philox
• Threefry

Secure PRNGs

• Block-Cipher in counter mode or output feedback mode
  • HMAC-DRBG
• Stream-Cipher

Subtypes

• Key Derivation Function