무선 네트워크를 위한 분산형 비밀 키 추출 방식

Abstract

In this paper, we present a secret key distribution protocol without resorting to a key management infrastructure targeting at providing a low-complexity distributed solution to wireless network. The proposed scheme extracts a secret key from the random fluctuation of wireless channels. By exploiting time division duplexing transmission, two legitimate users, Alice and Bob can have highly correlated channel gains due to channel reciprocity, and a pair of random bit sequences can be generated by quantizing the channel gains. We propose a novel adaptive quantization scheme that adjusts quantization thresholds according to channel variations and reduces the mismatch probability between generated bit sequences by Alice and Bob. BCH codes, as a low-complexity and pratical approach, are also employed to correct the mismatches between the pair of bit sequences and produce a secret key shared by Alice and Bob. To maximize the secret key extraction rate, the parameters, quantization levels and code rates of BCH codes are jointly optimized.