Sirius64: a new and promising PRNG

[A4H2024]

You might want to consider this interesting new PRNG: https://github.com/matteo65/Sirius64
Is what the documentation says true?

[sysaulab]

It passes my smoke tests : PractRand and a quick subset of NIST, I benchmark it faster than biski64 which is difficult to do. So for raw speed it seems ok, however it requires a lot more than passing a quick smoke test to consider an algorithm for cryptographic or serious usage. Thank you for pointing it out, I added it to my RNG playground.

Open questions / caveats.

Joint structure is the weak spot. The NIST failures (linear_complexity, runs, non_overlapping_template) are the tests most sensitive to incomplete diffusion over sliding windows. The 32‑bit occupancy test cannot see this — it only checks the marginal.

64‑bit bijectivity is unproven. The final state ^ z ^ (z >> 17) is an XOR of three quantities, not a composition of bijections, so full 2⁶⁴ coverage is not guaranteed. The only ways to settle it are a Z3 proof or a switch to a SplitMix64‑style composition of bijections.

Invertibility. A 64‑bit state means one output word plus knowledge of the algorithm recovers the internal state. Never use for crypto, never use where an adversary can see outputs.

Full‑period permutation is a statistical liability, not a feature. A true random source has ~37% missing values and Poisson(1) collisions; a permutation has zero. This makes collisions detectable.

Practical takeaway.

For games, simulations, procedural generation, and parallel streams with O(1) seeking: Sirius64 is competitive with biski64 and, on the reported numbers, sometimes faster.

It is not cryptographic and the project says so. Treat it as a fast, high‑quality non‑crypto PRNG in the SplitMix64/PCG class.

One‑line verdict for the Internet: A fast, single‑state, jump‑ahead‑friendly non‑crypto PRNG that passes NIST STS and 256 GB of PractRand, with a proven 32‑bit uniform marginal; 64‑bit bijectivity and diffusion‑sensitive tests still to be fully settled. Fun and games, not secrets.

Sorry Mr Lemire if I overstepped in your forums...