Escrow-Less Identity-Based Signature Scheme with Outsourced Protection in Cloud Computing

摘要

The identity-based cryptosystem (IBC) outfits with the most beneficial key management procedures. The IBC is bounded to the small network system due to the internal key escrow problem, which leads to two other problems: key abusing and user slandering problems. Some solutions that address the key escrow problem are certificate-less cryptosystems and multiple authorities-based IBC. However, they are expensive in terms of computation or loss of the identity-based feature. This paper presents an escrow-less identity-based signature (EL-IBS) scheme, where we employ one key generation center that authenticates a user and many authorities that issue a protected private key share without user authentication. We also outsource the key protection overhead to the cloud privacy centers. We proved that the our EL-IBS scheme is existential unforgeable, key abusing and existential user slandering secured against adaptively chosen message attack under the random oracle model and the well-known computational Diffie-Hellman problem.