A New Definition of Homomorphic Signature for Identity Management in Mobile Cloud Computing

In this paper, we define a new homomorphic signature for identity management in mobile cloud computing. A mobile user firstly computes a full signature on all his sensitive personal information (SPI), and stores it in a trusted third party (TTP). During the valid period of his full signature, if the user wants to call a cloud service, he should authenticate him to the cloud service provider (CSP) through TTP. In our scheme, the mobile user only needs to send a vector to the access controlling server (TTP). The access controlling server who doesn't know the secret key can compute a partial signature on a small part of user's SPI, and then sends it to the CSP. We give a formal secure definition of this homomorphic signature, and construct a scheme from GHR signature. We prove that our scheme is secure under GHR signature.