Hawkynt

Xoshiro256+

Xoshiro256+ is the fastest variant in the xoshiro256 family, using simple addition for the output function. It provides excellent speed but lower statistical quality compared to ++ and ** variants, making it suitable for floating-point generation using upper bits.

Properties

Property	Value
Category	Random Number Generators
Sub-category	Non-Cryptographic PRNG
Security status	🎓 Educational Only
Complexity	Intermediate
Inventor	David Blackman, Sebastiano Vigna
Year	2018
Origin	🇮🇹 Italy
Source	algorithms/random/xoshiro256plus.js

Parameters

Parameter	Supported values
Seed sizes	8 bytes (64 bits)

Capabilities

Flag	Value
IsDeterministic	Yes
IsCryptographicallySecure	No

Security

Status: 🎓 Educational Only

No vulnerabilities are recorded for this implementation.

Documentation

• Official Reference Implementation
• xoshiro / xoroshiro generators and the PRNG shootout
• Original Paper: Scrambled Linear Pseudorandom Number Generators (2018)

References

• Wikipedia: Xoroshiro128+
• PCG: A Quick Look at Xoshiro256**

Test vectors

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

Vector 1 — Seed=0: First four 64-bit outputs from xoshiro256+

Field	Value
seed	0000000000000000
outputSize	32
input	null
expected	9b4f6aede160acda3584c00ddaa15631ab46d085323ebaf9017bba1d6194d14f

Vector 2 — Seed=1: First four 64-bit outputs from xoshiro256+

Field	Value
seed	0100000000000000
outputSize	32
input	null
expected	cc2545777db4cb0226ab3444c2c0cde207787f4717e88f28d93b3442a433c9b8

Vector 3 — Seed=12345: First four 64-bit outputs

Field	Value
seed	3930000000000000
outputSize	32
input	null
expected	6a541006d790274fec20511df233aed2401ed003e26e8fa284753a5a7af43e21

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