The Protection Methods for Mobile Code Based on Homomorphic Encryption and Data Confusion

The research for homomorphic encryption and calculation of the encryption function based on homomorphic encryption is still in its infancy, and encryption functions has been limited to the rational polynomial function in the existing program, with polynomial framework message of encrypted functions still being plaintext. This paper proposes a calculating method of homomorphic encryption function for the program logic of mobile code and critical data carried, by using the homomorphic encryption to coefficient and the power homomorphic encryption to index, and adding a function item with the coefficient key zero to hide the skeleton information of polynomial better. The encryption functions computation based on homomorphic encryption and hiding method for data proposed in the paper, have properly solved protection of the program logic of mobile code and carried data. Encryption functions based on homomorphic encryption and data hiding can directly operate cipher text operation, with operation results being automatically encrypted. A further analysis shows that using the proposed method can accomplish non-interactive encrypted computation of elementary functions and provide a new method for the protection of mobile code.