charm-crypto-lite

Minimal elliptic curve cryptography for Python — a lightweight subset of the Charm Crypto Framework.

Why charm-crypto-lite?

Use charm-crypto-lite if you:

• Only need elliptic curve operations on secp256k1 (Bitcoin/Ethereum curve)
• Want zero Python dependencies and minimal C dependencies
• Need a lightweight package for serverless/containerized environments

Use charm-crypto-framework if you:

• Need pairing-based cryptography (ABE, IBE, signatures)
• Need multiple curve types or pairing groups
• Are building advanced cryptographic protocols

Installation

pip install charm-crypto-lite

Prerequisites: OpenSSL development libraries

# macOS
brew install openssl

# Ubuntu/Debian
sudo apt-get install libssl-dev python3-dev build-essential

Quick Start

from charm_lite.toolbox.ecgroup import ECGroup, ZR, G
from charm_lite.toolbox.eccurve import secp256k1

group = ECGroup(secp256k1)

# Get the generator point
g = group.generator()

# Generate random scalar (private key)
x = group.random(ZR)

# Scalar multiplication: public_key = g^x
pk = g ** x

# Point addition (multiplicative notation): p = h * k
h = g ** group.random(ZR)
p = pk * h

# Serialization
data = group.serialize(pk)
pk2 = group.deserialize(data)
assert pk == pk2

API Reference

ECGroup Operations

PKEnc Base Class

For building encryption schemes:

from charm_lite.toolbox.PKEnc import PKEnc

class MyScheme(PKEnc):
    def keygen(self): ...
    def encrypt(self, pk, msg): ...
    def decrypt(self, sk, ct): ...

Migrating to Full Charm

pip uninstall charm-crypto-lite
pip install charm-crypto-framework

Change imports from charm_lite to charm:

# Before
from charm_lite.toolbox.ecgroup import ECGroup

# After
from charm.toolbox.ecgroup import ECGroup

License

LGPL-3.0-or-later

Links

• Charm Crypto Framework
• Documentation