Threshold password-authenticated secret sharing (TPASS) protocols allow a client to distribute a secret s amongst n servers and protect it with a password pw, so that the client can later recover the secret s from any subset of t of the servers using the password pw. In this paper, we present two efficient TPASS protocols, one is built on two-phase commitment and has lower computation complexity, and another is based on zero-knowledge proof and has less communication rounds. Both protocols are in particular efficient for the client, who only needs to send a request and receive a response. In addition, we have provided rigorous proofs of security for the proposed protocols in the standard model. The experimental results have shown that the proposed two TPASS protocols are more efficient than Camenisch et al.’s protocols and save up to 85%–95% total computational time and up to 65%–75% total communication overhead.
- Diffie–Hellman problems
- ElGamal encryption scheme
- Shamir secret sharing scheme
- Threshold password-authenticated secret sharing protocol