In this paper, we propose a new type of threshold proxy signature scheme: hybrid threshold proxy signature (HTPS), in which a signature is cooperatively generated by the partial original signers themselves and the proxy signers on behalf of their own original signer in threshold proxy way. We formalize the notion of security for hybrid threshold proxy signature scheme and prove our schemes security, such as, distinguishability, verifiability, strong unforgeability, strong nonrepudiation, etc.
Analysis of Warrant Attacks on Some Threshold Proxy Signature Schemes