关键词: 数据加密, 变参数, Logistic映射, 输入-输出反馈

Abstract: A simple and fast encryption algorithm based on Logistic map is designed for the encryption of the information documents.In order to enhance the security of the encryption system and increase the key space，the Logistic map’s iterations are changed by the plaintext and ciphertext through a common feedback，and then the values of system parameters are altered by the iterative feedback.So the plaintext can be encrypted dynamically.The simulation results show that the encryption algorithm can effectively resist the common assault of chaotic systems，like phase diagrams attack，statistical attack，and brute-force attack.

Key words: data encryption, dynamic parameter, Logistic map, input-output feedback