Robust threshold DSS signatures

We present threshold DSS (digital signature standard) signatures where the power to sign is shared by n players such that for a given parameter t<n/2 any subset of 2t + 1 signers can collaborate to produce a valid DSS signature on any given message, but no subset of t corrupted players can forge a signature (in particular, cannot learn the signature key). In addition, we present a robust threshold DSS scheme that can also tolerate n/3 payers who refuse to participate in the signature protocol. We can also endure n/4 maliciously faulty players that generate incorrect partial signatures at the time of signature computation. This results in a highly secure and resilient DSS signature system applicable to the protection of the secret signature key, the prevention of forgery, and increased system availability. Assuming that secret communication between the players is available, we prove the security of our protocols solely based on the hardness of forging a regular DSS signature. © 2001 Academic Press.