A Rust workspace of no_std, dependency-free building blocks for cryptographic
and mathematical code. Each crate is published separately and keeps its own
README, changelog, and validation commands.
| Crate | Version | Description |
|---|---|---|
tc_constant_time |
  |
Masked selection, comparison, ordering, and conditional arithmetic without value-dependent branches. No dependencies, no feature flags, no alloc, no unsafe. |
tc_runtime |
  |
CPU feature detection and capability proof tokens for x86 and AArch64, used to select an optimized backend at runtime. Dependency-free by default; optional std and aarch64-detect features. |
tc_zeroize |
  |
Explicit memory erasure through volatile writes, with an opt-in drop guard and a marker for types that clear themselves. Dependency-free; a default-off alloc feature adds Vec<T> and Box<T>. |
tc_constant_time provides timing primitives rather than mathematical
operations, so cryptographic algorithms and mathematical backends can share it
without depending on each other. tc_runtime decides which backend runs;
tc_constant_time governs how a backend handles secret values; tc_zeroize
covers what happens to a secret once it is no longer needed. None of the three
depends on the others.
Rust 1.85 or later, edition 2024. Every crate builds without std, and none of
them allocates. Heap-backed types are reached only through tc_zeroize's
default-off alloc feature.
cargo test --locked
cargo test --locked --all-features
cargo fmt --all -- --check
cargo clippy --locked --all-targets --all-features -- -D warnings
cargo doc --locked --no-deps --all-features
CI additionally runs these on Linux x64, i686 and ARM64, macOS ARM64, and
Windows ARM64, checks the wasm32-unknown-unknown and aarch64-unknown-none
targets, pins an MSRV job to Rust 1.85.0, and verifies each crate's package
archive. See .github/workflows/ci.yml.
Licensed under either the MIT license or the Apache License, Version 2.0, at your option.