1. Rivest, R. L., Shamir, A., Adleman, L., A method for obtaining digital signatures and public key cryptosystems, Comm. ACM, 1978, 21: 120.
2. Salomaa, A., Public-Key Cryptography, New York: Springer-Verlag, 1990.
3. Cao Zhenfu, Public Key Cryptology (in Chinese), Harbin: Heilongjiang Education Press, 1993.
4. Sun, Qi, A kind of trap-door one-way functions over algebraic integer ring, Journal of Sichuan University (in Chinese), 1986, (2): 22.
5. Cao Zhenfu, Two new types of cryptosystems over Eisenstein’s ring ℤ[ω], J. Electronics, 1992, 14(3): 286.