Performance analysis of transmission over AWGN wiretap channels with practical codes

The wiretap coding problem has been addressed since a long time from an information theoretic standpoint. This has permitted to find the ultimate achievable limits under the hypothesis of random coding, which however is far from practice. Some families of practical codes have also been already considered in this scenario, but their achievable secrecy has mostly been assessed in asymptotic conditions (i.e., under the hypothesis of infinite codeword length) and using discrete channel models. In this chapter, we analyze the performance of practical codes over the Gaussian wiretap channel by using suitable metrics which take into account the codeword length and even the specific code structure. This way, we are able to assess the performance of real codes in the finite code length regime, and compare it with the ultimate achievable limits. We focus on low-density parity-check codes as they are among the most viable candidates for the use in this setting.