Random

thistle.random_bytes / random_fill

def random_bytes(n: Int) raises -> List[UInt8]
def random_fill(buf: UnsafePointer[UInt8, MutAnyOrigin], length: Int) raises

var key = random_bytes(32)
random_fill(existing_buf.unsafe_ptr(), 64)

Uses direct syscalls. getrandom(2) on Linux with EINTR retry. getentropy(2) on macOS chunked at 256 bytes. No /dev/urandom fd. Platforms without a secure source fail to compile. There is no weak fallback path.

• Note: raises on kernel failure. Always call it in a raises context.
• Note: this is not a PRNG. For bulk non-secret randomness where throughput or reproducibility matters use std.random instead. This module is syscall-bound and much slower for that use case.