Deniable authentication protocols allow a sender to authenticate a message for a receiver, in a way which the receiver cannot convince a third party that such authentication ever took place. When we consider an asynch...Deniable authentication protocols allow a sender to authenticate a message for a receiver, in a way which the receiver cannot convince a third party that such authentication ever took place. When we consider an asynchronous multi-party network with open communications and an adversary that can adaptively corrupt as many parties as it wishes, we present a new approach to solve the problem of concurrent deniable authentication within the framework of universally composable （UC） security. We formulate a definition of an ideal functionality for deniable authentication. Our constructions rely on a modification of the verifiably smooth projective hashing （VSPH） with projection key function by trapdoor commitment. Our protocols are forward deniable and UC security against adaptive adversaries in the common reference string model. A new approach implies that security is preserved under concurrent composition of an unbounded number of protocol executions; it implies non-malleability with respect to arbitrary protocols and more. The novelty of our schemes is the use of witness indistinguishable protocols and the security is based on the decisional composite residuosity （DCR） assumption. This new approach is practically relevant as it leads to more efficient protocols and security reductions.展开更多
基金the National Natural Science Foundation of China (Grant Nos. 60702059, 60633020 and 60573036)by the MIC of Korea, under the ITRC support program supervised by the IITA (IITA-2006-C1090-0603-0026)
文摘Deniable authentication protocols allow a sender to authenticate a message for a receiver, in a way which the receiver cannot convince a third party that such authentication ever took place. When we consider an asynchronous multi-party network with open communications and an adversary that can adaptively corrupt as many parties as it wishes, we present a new approach to solve the problem of concurrent deniable authentication within the framework of universally composable （UC） security. We formulate a definition of an ideal functionality for deniable authentication. Our constructions rely on a modification of the verifiably smooth projective hashing （VSPH） with projection key function by trapdoor commitment. Our protocols are forward deniable and UC security against adaptive adversaries in the common reference string model. A new approach implies that security is preserved under concurrent composition of an unbounded number of protocol executions; it implies non-malleability with respect to arbitrary protocols and more. The novelty of our schemes is the use of witness indistinguishable protocols and the security is based on the decisional composite residuosity （DCR） assumption. This new approach is practically relevant as it leads to more efficient protocols and security reductions.
