Research And Design Of LDPC-based Error Correcting Cipher

In recent years, with the development of communication technology and with the widely application of internet, information sharing becomes more and more important to almost every institution. At the same time, the problems of information security are sticking our daily. In transmission process, some important information needs not only security but also error resilience. Traditionally, these two step operations: encryption followed by error correction increasing the system complexity while producing some network delay. So jointing the two operations together will make the system more efficiency. McEliece joint error-correcting and encryption together based on algebraic coding theory firstly in 1978. then error correcting ciphers has attracted considerable attention in communication security. However, if such a joint system is not designed carefully, both error correcting capacity and security could be compromised. For this reason, the design of error correcting ciphers has remained an open problem for the past 30 years.In this paper, firstly, we give a simple introduction of the block cipher theory and the encoding/decoding theory of LDPC. Then we describe the works of researchers on this field.Secondly, we propose an error correcting block cipher: the LDPC error correcting cipher. We also present an error correcting cipher system mainly based on the LDPC error correcting cipher. The LDPC error correcting cipher which is based on the wide trail strategy is a six round block cipher that encrypts 256 bit plaintexts using secret key to produce 512 bit ciphertexts, and the key is composed of 128 bit AES secret key and LDPC generator matrix. By using the LDPC generator matrix with high performance in diffusion property, we made the LDPC error correcting cipher as secure as the Advanced Encryption Standard (AES) against linear, differential attacks in fewer rounds. Even the Square attack has no effect on attacking the cipher.Lastly, the process of encrypting/decrypting LDPC error correcting cipher is implemented, the cipher encryption/decryption system which is mainly based on the LDPC error correcting cipher is implemented, also the security and error correction capacity is analized.