ABE has been widely applied for secure data protection in cloud computing. In ABE, user's private keys are generated by attribute authority, thus, attribute authority has the ultimate privileges in the system and can impersonate any users to forge valid signatures. Once the attribute authority become dishonest or be invaded in cloud systems, the system's security will be at risk. To better solve the problem mentioned above, in this paper, we propose a key-policy attribute based signature scheme with untrusted authority and traceability (KP-ABS-UT). In our scheme, the signer's private key is composed by two components: one part is distributed by attribute authority and the other part is chosen privately by the signer's self. Thus attribute authority cannot forge any signatures which should be signed by legal users. Besides, our scheme introduces an entity "tracer", which can trace the identity of signer when necessary. By security analysis and efficiency comparison, we prove our KP-ABS-UT scheme meets the requirements of unforgeability as well as lower computation cost.
['Hanshu Hong', 'Zhixin Sun']
An efficient and traceable KP-ABS scheme with untrusted attribute authority in cloud computing