PURPOSE: A secure communication using error correction codes is provided to enable stable data communication by selecting the puncturing pattern distribution for an LDPC(Low Density Parity Check) code. CONSTITUTION: The puncturing pattern distribution for an LDPC(Low Density Parity Check) code is selected, and a security threshold and the reliability threshold for the LDPC are calculated. If the security gap for the LDPC is the lowest value(210) among the values indicated in the all previous repetitions, the selected puncturing pattern distribution is stored. Another puncturing pattern distribution for the LDPC is selected, and the steps are repeatedly performed. The LDPC has the selected puncturing pattern distribution and is described by the degree distribution.