Designated Verifier Threshold Proxy Signature Scheme without Random Oracles

In a (t, n) designated verifier threshold proxy signature scheme, an original signer can delegate his/her signing power to n proxy signers such that any t or more out of n proxy signers can sign messages on behalf of the original signer but t− 1 or less of the proxy signers cannot generate a valid proxy signature. Of course, the signature is issued for a designated receiver and therefore only the designated receiver can validate the proxy signature. In this paper, we propose a new designated verifier threshold proxy signature scheme and also show that the proposed scheme has provable security in the standard model. The security of proposed scheme is based on the GBDH assumption and the proposed scheme satisfies all the security requirements of threshold proxy signature schemes.