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.
资源授权决策是协作信息系统面临的首要安全问题。首先结合角色、时态和环境的概念,介绍了行为的含义和基于行为的访问控制模型ABAC(action-based access control model),然后基于ABAC模型,给出了协作信息系统访问控制机制的流程;提出了包含用户请求、用户身份、口令、角色、时态状态、环境状态、生命期等安全属性的安全关联及其产生方法;给出了一种安全认证协议,使用此协议可以实现用户与行为服务器、资源管理服务器之间交换与ABAC模型相关的安全属性,并使用UC模型证明该协议的安全性。
