PyFAEST - Python Bindings for FAEST

Python wrapper for the FAEST (Fast AES-based Signature with Tight security) post-quantum digital signature scheme.

Overview

FAEST is a post-quantum signature scheme submitted to the NIST PQC standardization process. This Python package provides high-level bindings to the C reference implementation:

• 🔐 Quantum-resistant signatures based on symmetric cryptography
• 🚀 High performance - Direct binding to optimized C code via CFFI
• 🛡️ Memory-safe - Automatic private key clearing
• 🎯 Pythonic API - Clean, intuitive interface
• 📦 12 parameter sets - All FAEST variants supported

Installation

From PyPI (Recommended)

pip install pyfaest

Pre-built wheels available for:

• Linux x86_64 (manylinux)
• macOS arm64 (Apple Silicon)
• Python 3.8, 3.9, 3.10, 3.11, 3.12, 3.13, 3.14

No compilation required! For other platforms, see installation guide.

From Source

git clone https://github.com/Shreyas582/pyfaest.git
cd pyfaest
pip install -e .

Quick Start

from faest import Keypair, sign, verify

# Generate a keypair
keypair = Keypair.generate('128f')

# Sign a message
message = b"Hello, quantum-resistant world!"
signature = sign(message, keypair.private_key)

# Verify the signature
is_valid = verify(message, signature, keypair.public_key)
print(f"Valid: {is_valid}")  # True

Parameter Sets

PyFAEST supports all 12 FAEST parameter sets:

Parameter Set	Security Level	Public Key	Private Key	Signature
128f	NIST Level 1	32 bytes	32 bytes	5,924 B
128s	NIST Level 1	32 bytes	32 bytes	4,506 B
192f	NIST Level 3	48 bytes	40 bytes	14,948 B
192s	NIST Level 3	48 bytes	40 bytes	11,260 B
256f	NIST Level 5	48 bytes	48 bytes	26,548 B
256s	NIST Level 5	48 bytes	48 bytes	20,696 B
em_128f	NIST Level 1	32 bytes	32 bytes	5,060 B
em_128s	NIST Level 1	32 bytes	32 bytes	3,906 B
em_192f	NIST Level 3	48 bytes	48 bytes	12,380 B
em_192s	NIST Level 3	48 bytes	48 bytes	9,340 B
em_256f	NIST Level 5	64 bytes	64 bytes	23,476 B
em_256s	NIST Level 5	64 bytes	64 bytes	17,984 B

Suffix meanings:

• f = Fast (optimized for speed)
• s = Small (optimized for signature size)
• em_* = Extended mode variants

Note: 192-bit variants have asymmetric key sizes (private=40, public=48) by design.

API Reference

Key Generation

from faest import Keypair

# Generate a new keypair
keypair = Keypair.generate('128f')

# Access individual keys
public_key = keypair.public_key
private_key = keypair.private_key
param_set = keypair.param_set

# Validate keypair
is_valid = keypair.validate()

Signing and Verification

from faest import sign, verify

# Sign a message
signature = sign(message, private_key)

# Verify a signature  
is_valid = verify(message, signature, public_key)

Key Serialization

# Export keys as bytes
pk_bytes = public_key.to_bytes()
sk_bytes = private_key.to_bytes()

# Import from bytes
keypair = Keypair.from_bytes(pk_bytes, sk_bytes, '128f')

# Or create keys individually
from faest import PublicKey, PrivateKey
public_key = PublicKey(pk_bytes, '128f')
private_key = PrivateKey(sk_bytes, '128f')

Error Handling

from faest import (
    FaestError,           # Base exception
    KeyGenerationError,   # Key generation failed
    SignatureError,       # Signing failed
    VerificationError,    # Verification failed
    InvalidKeyPairError,  # Keypair validation failed
)

try:
    keypair = Keypair.generate('128f')
    signature = sign(message, keypair.private_key)
except KeyGenerationError as e:
    print(f"Key generation failed: {e}")
except SignatureError as e:
    print(f"Signing failed: {e}")

Examples

Complete examples in the examples/ directory:

• basic_usage.py - Simple signing and verification
• all_parameter_sets.py - Testing all 12 parameter sets
• key_serialization.py - Key import/export patterns

Documentation

• Installation Guide - Detailed installation instructions
• Getting Started - Quick start tutorial
• Developer Guide - Architecture and internals
• Maintainer Guide - Release and publishing

Requirements

• Python 3.8 or higher
• Linux x86_64, macOS arm64, or Windows (via WSL)
• CFFI >= 1.15.0 (automatically installed)

Note: Pre-built wheels eliminate the need for compilers or build tools.

Security Considerations

⚠️ Important Security Notes:

• Reference implementation - Not yet optimized for production
• NIST evaluation - FAEST is a candidate, not yet standardized
• Memory safety - Private keys automatically cleared from memory
• Side channels - No protection against timing/power analysis attacks
• Secure storage - Store private keys encrypted at rest

Performance

Typical performance on modern hardware (single core):

Operation	128f	128s	256f	256s
Key generation	~1 ms	~1 ms	~2 ms	~2 ms
Signing	~5 ms	~8 ms	~15ms	~25ms
Verification	~5 ms	~8 ms	~15ms	~25ms

f variants are faster, s variants produce smaller signatures.

Platform Support

Platform	Status	Notes
Linux x86_64	✅ Supported	Pre-built wheels
macOS arm64	✅ Supported	Pre-built wheels (Apple Silicon)
Windows (WSL)	✅ Supported	Use Linux wheels in WSL
macOS x86_64	⚠️ Source	Build from source (Intel Macs)
Linux aarch64	⚠️ Source	Build from source (ARM64 Linux)
Windows native	❌ Not supported	Use WSL instead

Development

Running Tests

pip install pytest
pytest tests/ -v

Building from Source

See INSTALLATION.md for detailed instructions.

Quick version:

# Build FAEST C library first
git clone https://github.com/faest-sign/faest-ref.git
cd faest-ref
meson setup build
meson compile -C build

# Install PyFAEST
cd /path/to/pyfaest
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

# Copy library files
FAEST_REF=/path/to/faest-ref bash scripts/update_libraries.sh

# Install in development mode
pip install -e .

# Verify
python verify_install.py

Project Structure

pyfaest/
├── faest/              # Python package
│   ├── __init__.py     # Public API exports
│   └── core.py         # Main implementation (550+ lines)
├── lib/                # Bundled FAEST libraries
├── include/            # C header files  
├── examples/           # Usage examples
├── tests/              # Test suite (37 tests)
├── docs/               # Documentation
├── scripts/            # Build/release scripts
├── faest_build.py      # CFFI build script
└── setup.py            # Package configuration

License

MIT License - See LICENSE file for details.

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes with tests
4. Submit a pull request

See DEVELOPER_GUIDE.md for more details.

Citation

If you use PyFAEST in research, please cite:

@software{pyfaest,
  title = {PyFAEST: Python Bindings for FAEST},
  author = {PyFAEST Contributors},
  year = {2025},
  url = {https://github.com/Shreyas582/pyfaest}
}

References

• FAEST Official Website
• FAEST Specification
• NIST PQC Project
• faest-ref GitHub

Changelog

See CHANGELOG.md for version history.

Support

• Issues: GitHub Issues
• Documentation: docs/
• Examples: examples/

Acknowledgments

PyFAEST is built on top of the FAEST reference implementation by the FAEST team. Special thanks to all contributors to the FAEST project.

NOTE from Author

I have created this for a Post-Quantum Cryptography class project at NYU.