Hawkynt

Wichmann-Hill

Combined random number generator using three Linear Congruential Generators with large prime moduli near 2^64. This modernized variant improves upon the original 1982 AS183 algorithm by using 64-bit arithmetic and larger primes, providing an extremely long period and better statistical properties than simple LCGs.

Properties

Property	Value
Category	Random Number Generators
Sub-category	Pseudorandom Number Generator
Security status	🎓 Educational Only
Complexity	Intermediate
Inventor	Brian Wichmann and David Hill
Year	1982
Origin	🇬🇧 United Kingdom
Source	algorithms/random/wichmann-hill.js

Parameters

Parameter	Supported values
Seed sizes	1 byte (8 bits) to 32 bytes (256 bits)

Capabilities

Flag	Value
IsDeterministic	Yes
IsCryptographicallySecure	No

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• Wichmann, B.A. and Hill, I.D. (1982): Algorithm AS 183: An Efficient and Portable Pseudo-random Number Generator (Applied Statistics 31:188-190)
• McLeod, A.I. (1985): Remark AS R58: A Remark on Algorithm AS 183 (Applied Statistics 34:198-200)
• Wikipedia: Wichmann-Hill Generator

References

• Original AS183 Paper - Applied Statistics
• Wichmann-Hill Implementation Guide

Test vectors

5 vectors ship with this algorithm and run in the test suite. Byte values are hexadecimal.

Vector 1 — Modernized 64-bit variant, seed=1 - First 5 values (8 bytes each)

Field	Value
seed	0000000000000001
outputSize	40
input	null
expected	0657c71cd00132e59be711b3d64ccd31 a5c923bdd09ac22a4ec5b77f8af1e2a8 164d1e21fc54f174

Vector 2 — Modernized 64-bit variant, seed=42 - First 5 values (8 bytes each)

Field	Value
seed	000000000000002a
outputSize	40
input	null
expected	2b77e25e13f294543f54be2cb9ed2c4b 9753deeaedce96af456610eb40b08e51 5a4bf254af2dd91b

Vector 3 — Modernized 64-bit variant, seed=12345 - First 5 values (8 bytes each)

Field	Value
seed	0000000000003039
outputSize	40
input	null
expected	b60daf6198914a4e0e408acd97013b5b 7f61c25c0fb4e029a647db70cc8d51ea 1a632a25e20f99a6

Vector 4 — Modernized 64-bit variant, seed=1000000 - First 5 values (8 bytes each)

Field	Value
seed	00000000000f4240
outputSize	40
input	null
expected	321e08c3a86eb0b0de16241ceed7a4f1 b99dafa2c41ec0c856b8244ab00a908c 731d999437b7ba88

Vector 5 — Modernized 64-bit variant, seed=0xDEADBEEF - First 5 values (8 bytes each)

Field	Value
seed	00000000deadbeef
outputSize	40
input	null
expected	40c8cd72a36b85bb0a9004ff6b8dedb3 0a88e02dbbd1b206ebabb900fc54a2c9 bd136837299fd960

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