Paper 2023/1785 Original: eprint.iacr.org/2023/1785 ↗

Non-Interactive Distributed Key Management with Pre-Determined Shares

Abstract

In distributed key management systems, a key can be generated in a centralized or distributed way. However, centralized schemes (e.g., Shamir's secret sharing) require a trusted dealer to perform a private setup to generate a key, which suffers from the single-point-of-failure problem; distributed schemes (e.g., distributed key generation, DKG) require a set of members (who form a committee) to interact with each other to generate the key, which introduces considerable communication costs. Furthermore, neither of them supports pre-determined shares. In this paper, we propose a Non-Interactive Distributed Key Management scheme, dubbed NIDKM, which enables members to generate a key and then recover it with a majority of them in a non-interactive way. We stress that NIDKM is different from existing threshold secret sharing schemes, but the threshold property remains: in NIDKM, the shares are first determined, and the key is derived from the shares; in existing schemes, the key is first generated, and then the shares are computed from the key. In addition, NIDKM does not require the members to interact with each other, which achieves $O(1)$ communication overhead on the member side. We formally prove NIDKM's security, implement its prototype, and conduct a comprehensive performance evaluation to demonstrate its high efficiency.