Simulatability and Security of Certificateless Threshold Signatures without Random Oracles

The idea of threshold cryptography is to distribute secret information and computation among multi parties in order to prevent a single point of failure or abuse. Certificateless public key cryptography(CL-PKC) does not require certificates to guarantee the authority of public keys while avoids the inherent key escrow of identity-based cryptography(IBC). In this paper, we propose a certificateless threshold signature scheme with concrete implementation which is probably secure in the standard model. Furthermore, this scheme is proven secure against the malicious-but-passive KGC attack. To the best of authors´ knowledge, this is the first construction of certificateless threshold signature scheme that does not rely on random oracle or ideal ciphers.