本文提出了一种基于Shannon（香农）信息论的、利用超长序列伪随机码作密钥源的保密通信系统。该系统有一次一钥密码系统的不可破译性，又克服了一次一钥系统需要保存大量密码的缺点，是一种实用新技术。文中给出了利用新型单片机构成加密盒和解密盒的原理，以及利用此加密、解密盒与三台PC机构成的实验保密通信系统。结果令人满意。 This paper presents a secure communication system based on the Shannon (Shannon) information theory and using a pseudo-random key with a very long sequence as the key source. The system once has a key cryptographic system can not be deciphered, but also overcome the shortcomings of a key system need to save a large number of passwords is a practical new technology. The paper presents the principle of using a new type of single chip microcomputer to form an encryption box and a decryption box, and an experimental confidential communication system using the encryption and decryption box and three PC units. The result is satisfactory.