Hawkynt

Threefry2x64-20

Counter-based PRNG using Threefish block cipher round function. Trivially parallelizable with 2^128 period, passes all TestU01 statistical tests. Part of the Random123 library by D. E. Shaw Research.

Properties

Property	Value
Category	Random Number Generators
Sub-category	Counter-Based PRNG
Security status	🎓 Educational Only
Complexity	Advanced
Inventor	John K. Salmon, Mark A. Moraes, Ron O. Dror, David E. Shaw
Year	2011
Origin	🇺🇸 United States
Source	algorithms/random/threefry.js

Parameters

Parameter	Supported values
Key sizes	16 bytes (128 bits)

Capabilities

Flag	Value
IsDeterministic	Yes
IsCryptographicallySecure	No
IsCounterBased	Yes

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• Original Paper: Parallel Random Numbers: As Easy as 1, 2, 3 (SC11, 2011)
• Random123 Library Documentation
• Random123 GitHub Repository
• Threefry Header Reference

References

• TestU01 Statistical Testing Suite
• Threefish Block Cipher Specification

Test vectors

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

Vector 1 — Threefry2x64-20: Counter=0, Key=0 - Random123 kat_vectors

Field	Value
key	00000000000000000000000000000000
outputSize	16
input	00000000000000000000000000000000
expected	6598c6c2a8e3b6c24d0850f342ed816f

Vector 2 — Threefry2x64-20: Counter=0xFFFFFFFFFFFFFFFF (all), Key=0xFFFFFFFFFFFFFFFF (all) - Random123 kat_vectors

Field	Value
key	ffffffffffffffffffffffffffffffff
outputSize	16
input	ffffffffffffffffffffffffffffffff
expected	7a275dd9c4b72ce0688b3b89d03366d0

Vector 3 — Threefry2x64-20: Counter=π digits, Key=π digits - Random123 kat_vectors

Field	Value
key	d0319f29223809a4896c4eec98fa2e08
outputSize	16
input	d308a385886a3f24447370032e8a1913
expected	f10a0fbb307d3c26261531d36183be56

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