Threshold-optimal DSA/ECDSA signatures and an application to Bitcoin wallet security.

While threshold signature schemes have been presented before, there has never been an optimal threshold signature algorithm for DSA. The properties of DSA make it quite challenging to build a threshold version. In this paper, we present a threshold DSA scheme that is efficient and optimal. We also present a compelling application to use our scheme: securing Bitcoin wallets. Bitcoin thefts are on the rise, and threshold DSA is necessary to secure Bitcoin wallets. Our scheme is the first general threshold DSA scheme that does not require an honest majority and is useful for securing Bitcoin wallets.