Quantum-Safe Threshold Cryptography for Decentralized Group Key Management via Dealerless DKG (CRYSTALS–Kyber)

Abstract

Post-quantum threshold cryptography requires complete elimination of classical assumptions to achieve genuine quantum resistance. This work presents a fully lattice-based dealerless distributed key generation (DKG) protocol with threshold CRYSTALS–Kyber implementation. We implemented a four-phase DKG protocol using lattice-based primitives: SIS-based commitments for verification, Ring-LWE secret sharing, and secure multi-party key derivation without reconstructing private keys. Our approach eliminates the need for a trusted dealer while maintaining 192-bit post-quantum security through exclusive reliance on lattice problems. Experimental evaluation demonstrates (Formula presented.) communication complexity for lattice-based DKG setup across 3-20 participants, with secure threshold operations preserving key secrecy. Security analysis provides formal reductions to Ring-LWE and Ring-SIS assumptions, ensuring genuine quantum resistance throughout the protocol stack. © 2025 by the authors.