  In this work we study the reliability and secrecy performance achievable by
practical LDPC codes over the Gaussian wiretap channel. While several works
have already addressed this problem in asymptotic conditions, i.e., under the
hypothesis of codewords of infinite length, only a few approaches exist for the
finite length regime. We propose an approach to measure the performance of
practical codes and compare it with that achievable in asymptotic conditions.
Moreover, based on the secrecy metrics we adopt to achieve this target, we
propose a code optimization algorithm which allows to design irregular LDPC
codes able to approach the ultimate performance limits even at moderately small
codeword lengths (in the order of 10000 bits).
