A Traceable Signcryption Scheme for Secure Sharing of Data in Cloud Storage

摘要

Nowadays cloud servers become the primary choice to store and share data with multiple recipients. The storage of personal information on cloud servers may result in the exposure of confidential information to unauthorized individuals or organizations. Several solutions employing attribute-based encryption schemes have been proposed for secure sharing of data using cloud servers. However, most of the solutions fail to trace the traitors, who intentionally leaked their data access privileges for personal gain. This paper introduces a traceable ciphertext policy attribute-based signcryption (sign-then-encrypt) scheme to simultaneously realize the notion of traitor-tracing, fine-grained access control, sender anonymity, message integrity, authenticity and sensitivity by extending traceable attribute based encryption scheme using attribute-based signature. Single authority may compromise user's key. Hence to reduce the trust on authority, our proposed scheme employs different authorities for key generation and traitor-tracing. In addition, our proposed scheme preserves message sensitivity by allowing the data-owner to define message category label. We analyze the performance of our scheme with respect to secret key size, ciphertext size, computation cost involves in signcryption and designcryption and compare it with existing schemes to show its efficacy.