Two efficient generic patterns for convertible limited multi-verifier signature

A convertible limited multi-verifier signature (CLMVS) provides controlled verifiability and preserves privacy of the signer. Furthermore, limited verifiers can designate the signature to a third party or convert it to a publicly verifiable signature when necessary. However, constructing an efficient scheme with a unique signature for more than two limited verifiers is remained unsolved. In this study, we first derive the general pattern of convertible limited verifier signatures (CLVS) which previous secure CLVS schemes fit into this pattern. Then, we extend the pattern to produce two CLMVS schemes which are efficient in the sense of generating a unique signature for more than two limited verifiers. In the first scheme, each limited verifier can check the validity of the signature solely and in the second scheme, cooperation of all limited verifiers is necessary. Finally, based on our second generic pattern, we present the first pairing based CLMVS scheme secure in the standard model which has strong confirmation property.