Cryptographic MultiPrecision Arithmetic (cmpa)

Pure Rust implementation of multiprecision arithmetic primitives commonly needed for asymmetric cryptography.

rustdoc comments are WIP.

Features

• [no_std]
• Rigorously constant-time throughout.
• Complete user control over buffers: cmpa does not allocate any own its own or places any on the stack. Whenever scratch space is needed for some computation, a buffer is provided as an additional argument to the API.

Functionality overview

• Operates on multiprecision integers in big or little endian format (stored as byte slices) or more effeciently on native format multiprecision integers (stored as a slice of machine words).
• "Standard" airhtmetic: addition, subtraction, multiplication, division, shifts, comparisons etc.
• Modular arithmetic: Montogomery multiplication and related functionality, modular inversions etc.
• Primality testing.

Cargo features

• zeroize - implement traits from the zeroize crate.
• enable_arch_math_asm - Use (rather trivial) assembly implementations for certain basic sinlge-word arithmetic primitives. You most likely want to enable it for performance reason, but it does introduce some unsafe{} blocks.