Implemented Schemes¶

This section contains documentation for all cryptographic schemes implemented in Charm. Schemes are organized by type: attribute-based encryption (ABE), public-key encryption, public-key signatures, identity-based encryption, threshold signatures, and more. Each scheme includes implementation details, security assumptions, and usage examples.

Threshold Signatures¶

Charm provides three production-ready threshold ECDSA implementations for MPC-based distributed signing. These enable t-of-n signing where any t parties can collaboratively produce a valid signature without reconstructing the private key.

Scheme	Description	Reference
GG18	Classic Paillier-based threshold ECDSA (4-round interactive signing)	Gennaro & Goldfeder 2018
CGGMP21	UC-secure with identifiable aborts and presigning	Canetti et al. 2021
DKLS23	OT-based MtA with non-interactive presigning	Doerner et al. 2023

All schemes support secp256k1 (Bitcoin, XRPL) and other elliptic curves. See Threshold ECDSA for detailed documentation, API reference, and usage examples.

Quick Example (GG18):

from charm.toolbox.ecgroup import ECGroup
from charm.toolbox.eccurve import secp256k1
from charm.schemes.threshold import GG18

group = ECGroup(secp256k1)
gg18 = GG18(group, threshold=2, num_parties=3)
key_shares, public_key = gg18.keygen()
signature = gg18.sign(key_shares[:2], b"message")
assert gg18.verify(public_key, b"message", signature)