An Attribute-Based Encryption Scheme Secure against Malicious KGC

Different from identity-based encryption scheme, an attribute-based encryption scheme is a scheme in which each user is identified by a set of attributes, and some function of those attributes is used to determine decryption ability for each ciphertext. But key escrow problem is also the inherent problem in attribute-based encryption scheme. To avoid the problem of key escrow, this paper presents an attribute-based encryption scheme by use of another secret key that the KGC cannot obtain. Following, based on a concrete attribute-based encryption scheme insecure against malicious KGC, we give a scheme secure against malicious KGC. Furthermore, compared with the original scheme, our scheme doesn´t increase the length of the public key and the ciphertext. The security of our scheme is obtained directly from the security of the original scheme.