GitHub - aabmets/quantcrypt: Cross-platform Python library for Post-Quantum Cryptography using precompiled PQClean binaries

NOTICE: Intent of Archival

This project will be marked as read-only together with the PQClean project in July of 2026.
Please migrate your code to any alternative implementations, if any exist at all for Python.
Please refer to issue PQClean/PQClean#604 for more information.

Description

QuantCrypt is a cross-platform Python library for Post-Quantum Cryptography using precompiled PQClean binaries. While QuantCrypt contains multiple variants of PQC algorithms that are standardized by NIST, it is recommended to use only the strongest variants as recommended by the CNSA advisory by NSA.

Motivation

Currently, there does not exist any pure-Python implementation of Post-Quantum Cryptographic algorithms, which requires Python developers to first discover where to get reliable C source code of PQC algorithms, then install the necessary C compilers on their system and then figure out how to use CFFI to compile and use the C code in their Python source code. Furthermore, those binaries would be only compatible with the platform that they were compiled on, making it very difficult to use separate platforms for development and deployment workflows, without having to recompile the C source code each time.

This library solves this problem by pre-compiling the C source code of PQC algorithms for Windows, Linux and Darwin platforms in GitHub Actions using CFFI, and it also provides a nice Python wrapper around the PQC binaries. Since I wanted this library to be all-encompassing, it also contains a lot of helper classes which one might need when working with Post-Quantum cryptography. This library places a lot of focus on Developer Experience, aiming to be powerful in features, yet easy and enjoyable to use, so it would just work for your project.

Quickstart

The full documentation of this library can be found in the Wiki. Because this library is rich in docstrings which provide detailed insight into the library's behavior, it is suggested to use an IDE which supports autocomplete and code insights when working with this library. Most popular choices are either PyCharm or VS Code with Python-specific plugins.

Install

To install QuantCrypt with its default dependencies (no compiler), use one of the following commands:

Using UV (recommended):

Using Poetry:

Using pip:

If you want to recompile PQA binaries on your own machine, you can install QuantCrypt with optional dependencies by appending [compiler] to one of the install commands outlined above.

QuantCrypt publishes prebuilt wheels with precompiled binaries to the PyPI registry. If your platform supports one of the prebuilt wheels, then you don't need to install QuantCrypt with the compiler option to be able to use the library.

Note: If you do decide to recompile PQA binaries, you will need to install platform-specific C/C++ build tools like Visual Studio, Xcode or GNU Make (non-exhaustive list).

Note: If you attempt to import the compiler module programmatically when optional dependencies are missing, you will receive an import error.

Script Imports

from quantcrypt import (
    kem,      # Key Encapsulation Mechanism algos   - public-key cryptography
    dss,      # Digital Signature Scheme algos      - secret-key signatures
    cipher,   # The Krypton Cipher                  - symmetric cipher based on AES-256
    kdf,      # Argon2 helpers + KMAC-KDF           - key derivation functions
    errors,   # All errors QuantCrypt may raise     - also available from other modules
    utils,    # Helper utilities from all modules   - gathered into one module
    compiler  # Tools for compiling PQA binaries    - requires optional dependencies
)

CLI Commands

The general functionality of this library is also available from the command-line, which you can access with the qclib command. Keep in mind that if you install QuantCrypt into a venv, you will need to activate the venv to access the CLI. QuantCrypt uses Typer internally to provide the CLI experience. You can use the --help option to learn more about each command and subcommand.

qclib --help
qclib --version

qclib info --help
qclib keygen --help
qclib encrypt --help
qclib decrypt --help
qclib sign --help
qclib verify --help
qclib remove --help
qclib compile --help

Note: The compile CLI command becomes available when QuantCrypt has been installed with optional dependencies for the compiler.

Security Statement

The PQC algorithms used in this library inherit their security from the PQClean project. You can read the security statement of the PQClean project from their SECURITY.md file. To report a security vulnerability for a PQC algorithm, please create an issue in the PQClean repository.

Credits

This library would be impossible without these essential dependencies:

PQClean - C source code of Post-Quantum Cryptography algorithms
Cryptodome - AES-256 and SHA3 implementation
Argon2-CFFI - Argon2 KDF implementation

I thank the creators and maintainers of these libraries for their hard work.