CHAOTIC CRYPTOGRAPHY FOR OFDM BASED COMMUNICATIONS SYSTEMS

摘要

A chaotic cryptographic technique for orthogonal frequency division multiplexing (OFDM) based wireless/wired communication systems is implemented with an OFDM symbol structure based on symmetric key cryptography. At the receiver side, data detection becomes infeasible without knowledge of the secret key. Without the knowledge of the key, the signal will be a noise-like signal. The computational power required to implement the technique is very low, rendering the system an attractive option for high data rate communications based on OFDM technology. The system security is proportional to (L×N)! where N is the number of subcarriers in the OFDM system and L is the number of OFDM symbols involved in the encryption process. For OFDM applications where ≧256, L may be set to 1 and breaking the system would require N! exhaustive-search trials. In the case that N256, L may be increased.