## Cryptology ePrint Archive: Report 2012/488

Designated Verifier Threshold Proxy Signature Scheme without Random Oracles

Mohammad Beheshti-Atashgah \and Majid Bayat \and Mahmoud Gardeshi \and Mohammad Reza Aref

Abstract: 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.

Category / Keywords: public-key cryptography / Proxy signature scheme, Threshold proxy signature scheme, Provable security, Standard model, Bilinear pairing.