Isaac.jl

ISAAC (Indirection, Shift, Accumulate, Add, and Count) generates pseudorandom numbers. The original C reference version was developed by Robert J. Jenkins Jr. and is available from the ISAAC home page.

How secure is it? See the home page, and pay attention to Jenkins' warning:

Seeding a random number generator is essentially the same problem as encrypting the seed with a block cipher. ISAAC should be initialized with the encryption of the seed by some secure cipher.

I am definitely not an expert, but there appears to be no public evidence (see e.g. Wikipedia that the cipher has been broken.

Two versions of ISAAC generator are provided:

• Isaac32 generates 32-bit unsigned integers
• Isaac64 generates 64-bit unsigned integers

The two generators use different algorithms, and will produce different numbers given the same seed. Both generators are subtypes of Random.AbstractRNG and can be used (I hope) with the same methods provided by Random in the Julia standard library (Thanks to StableRNGs for showing me how to do this).

Three construction methods are available for each generator:

• Isaac32(), Isaac64() are default constructors (equivalent to an empty seed)
• Isaac32(seed::AbstractVector{UInt8}), Isaac64(seed::AbstractVector{UInt8}) use the items in seed to seed the generator
• Isaac32(seed::AbstractString), Isaac64(seed::AbstractString) use the bytes in seed to seed the generator

• isaac_rand(rng::Union{Isaac32, Isaac64}) provides underlying access to the next value generated (either UInt32 or UInt64. This method is not exported.
• Random.seed!(rng::Union{Isaac32, Isaac64}, seed) will re-seed rng with seed. This is used by the constructors, and seed can have the same types as in the constructors.
• rand(rng::Union{Isaac32, Isaac64}, ::Type{T}, n = (1, )) where T can be any of the types available to the standard Julia Random.rand(...) methods.
• Other methods such as randn(rng::Union{Isaac32, Isaac64},...), shuffle(rng::Union{Isaac32, Isaac64},...) are accessible if Random is used or imported.

Most of the original code is marked as being in the public domain. This version has been released under the MIT License, which is intended to mean that whatever is working should be accredited to Robert J. Jenkins Jr. Whatever is broken is probably my fault.