Practical Secret Signature Scheme with No Randomness Saving

Secret signatures, proposed by Lee \textit{et al.} \cite{LCYY07,LLK09}, provide signature privacy and public provability at the same time. Using these schemes a signer can send his signature secretly to a designated receiver such that only the designated receiver can verify the signature. Moreover, if any argument occurs between them, the validity of the secret signature can be proven publicly either by the signer or the receiver. But in these...