On analog of the RSA

Based on the polynomial property over finite fields F p, the analog of the RSA type pulbic key cryptosystem presented in the paper by ZhenFu Cao is modified. It is shown that the ciphertext extension problem in his system no longer exists by properly choosing some parameters. And the security of the new cryptosystem is also discussed. Finally a new analog of the RSA is given, which has no ciphertext extension and is more similar to the standard concept of RSA.