Attribute based generalized signcryption for online social network

Online social network has brought varies and flexible secure demands. Attribute based generalized signcryption (ABGSC) could bring the combined or separate confidentiality and authentication adaptively, and eliminate the bottleneck of traditional public key encryption. We proposed an attribute based generalized signcryption with non-monotonic access structures, which can perform signcryption, encryption and signature adaptively. The non-monotonic access structure is used to realize the “OR”, “AND”, “NEG” and “Threshold” operations; the Inner Product is used to achieve constant cipher text. Under the encryption mode, the cipher text length is 2|G|+nm, under the signature mode it is 3|G|+nm, and under the signcryption mode is 5|G|+nm, so we can improve the efficiency greatly. Under the q-DBDHE assumption in the stand model, the scheme is proved confidential under the signcryption and encryption mode, and is proved unforgeable under the signcryption and signature mode.