module-lwe 0.1.5

Implements the module learning-with-errors public key encrpytion scheme.
Documentation

module-LWE

Workflow Status License: MIT Crates.io

A pure Rust implementation of the Module Learning With Errors (module-LWE) encryption scheme.

📖 Description

This crate implements basic public-key encryption (PKE) operations — key generation, encryption, and decryption — based on the Module-LWE problem, a lattice-based post-quantum cryptographic assumption.

⚠️ Security Warning

This library is not secure.

It is:

  • Not constant-time
  • Not hardened against timing, cache, or other side-channel attacks
  • Intended only for educational and experimental purposes

Do not use this in production or real-world cryptographic systems.

🔧 Usage

Ensure you're in the project root:

cargo build

Builds the module.

cargo test

Runs tests to verify:

  • Keygen, encryption, and decryption round-trip correctness
  • Homomorphic addition and multiplication (limited cases)

🧪 Command-line Options

The binary accepts optional parameters using:

--n <n> --q <q> --k <k>

Where:

  • n: Polynomial degree
  • q: Ciphertext modulus
  • k: Module rank

If omitted, defaults are: n = 512, q = 12289, k = 8.

💻 Example Commands

cargo run -- keygen --save-keys

Generates a public/secret keypair and saves the keys to files secret.key and public.key.

cargo run -- encrypt --pubkey-file public.key "Hello, world!" --ciphertext-file ciphertext.txt

Encrypts the message using the given public key and save to the file ciphertext.txt.

cargo run -- encrypt --pubkey-file public.key "Hello, world!" --n 256 --q 7681 --k 4

Encrypt with custom parameters n, q, k using the public key file public.key.

cargo run -- decrypt --secret-file secret.key --ciphertext-file ciphertext.txt

Decrypts the ciphertext using the given secret key and prints to the command line.

📊 Benchmarks

n q k KeyGen Encrypt Decrypt KeyGen (str) Encrypt (str) Decrypt (str)
256 12289 2 146.66 µs 194.11 µs 61.53 µs 230.43 µs 255.60 µs 88.29 µs
256 12289 4 562.56 µs 622.29 µs 118.37 µs 819.22 µs 787.60 µs 167.38 µs
384 12289 4 1.177 ms 1.347 ms 260.02 µs 1.554 ms 1.583 ms 332.87 µs
512 12289 4 1.196 ms 1.360 ms 260.77 µs 1.717 ms 1.698 ms 356.75 µs
512 12289 8 4.699 ms 4.876 ms 518.81 µs 6.413 ms 5.792 ms 677.05 µs

🧐 Educational Focus

This crate is meant to help explore:

  • Algebraic structure of Module-LWE
  • Effects of parameter choices on performance
  • Polynomial arithmetic over rings

For real cryptographic implementations, refer to:

📄 License

MIT License © 2025
Part of the lattice-based-cryptography project.