CSI‑FiSh – Isogeny‑Based Signatures in Rust

⚠️ Experimental code. Use at your own risk.

CSI‑FiSh (csifish crate) is a pure‑Rust implementation of the CSI-FiSh: Efficient Isogeny based Signatures through Class Group Computations

The design combines Supersingular Isogeny techniques with class‑group computations to obtain post‑quantum signatures with very small public keys.

This repo provides:

• Blinded, constant‑time arithmetic for the quadratic‑imaginary class group underlying CSI‑FiSh.
• Trait‑based API for key generation, signing and verification.
• Rayon parallelisation (parallel Cargo feature).

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Minimum requirements

	Version / tool
Rust	nightly 1.78 or newer (uses generic_const_exprs)
GMP	6.2+ development headers (via rug / gmp-mpfr-sys)
OS	Linux, macOS, Windows (x86_64 / AArch64 tested)

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Building

git clone https://github.com/your‑org/csifish.git
cd csifish
rustup toolchain install nightly
rustup override set nightly
cargo build --release        # add --features parallel for multithreading

Running the small self‑tests:

cargo test --release

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Quick start

use csifish::csifish::signature::SigningKey;

const CURVES: u32 = 256;   // security parameter
const ROUNDS: u32 = 7;     // number of Fiat–Shamir rounds
const HASHES: u32 = 11;    // leaves per Merkle proof

fn main() {
    // 1.  Generate a signing key (= secret key)
    let sk = SigningKey::<CURVES, ROUNDS, HASHES>::generate();
    let vk = sk.verifying_key();           // derive verifying (public) key

    // 2.  Sign arbitrary messages
    let msg = b"🐟 post‑quantum ahoy!";
    let sig = sk
        .try_sign(msg)                    // Signer trait provides try_sign()
        .expect("failed to sign");

    // 3.  Verify signatures
    vk.verify(msg, &sig).expect("invalid signature");
}

See examples/ for complete runnable programs.

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Crate features

Feature	Default	Description
parallel	❌	Enable Rayon‑backed ParallelIterator implementations
use-system-libs	❌	Link against the system‑installed GMP instead of the bundled one

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Security Notice

Although care was taken to follow constant‑time coding practices, this code is not guaranteed to be constant-time. Do not deploy in production systems or handle sensitive key material.

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License

This project is distributed under the terms of the MIT license. See LICENSE for details.