An Efficient Revocable Attribute-Based Signcryption Scheme With Outsourced Unsigncryption in Cloud Computing

In this paper, we present an efficient revocable signcryption (CP-ABSC) with outsourced unsigncryption scheme based on ciphertext-policy attribute based encryption (CP-ABE) to secure the data sharing in cloud computing that require access control, data encryption, and authentication to ensure message integrity and confidentiality. It can be used to signcrypt a message based on the access rights specified by the message itself. A user can decrypt a ciphertext if and only if it possesses the attributes required by the access structure of the data. Thus CP-ABSC felxible encrypts data based on the access rights of the data specified by the data itself, which differs significantly from the traditional encryption where the user can decrypt is predetermined and must be known by the data source. In addition, the proposed scheme handles attributes revocation with high efficiency and demands low computation overhead on users' device during unsigncryption phase. Our scheme provides collusion attack resistance, message authentication, forgery prevention, and confidentiality. Furthermore, we compare the performance of our scheme with others in terms of the ciphertext, key size, computation cost and functionality.