Techniques are described for encoding information data bits using a low-density parity-check matrix optimized for a Low-Density Parity-Check (LDPC) encoder. In an example, the parity-check matrix includes a first matrix and a second matrix. The second matrix is a square matrix, and is also a block diagonal matrix that includes a set of square submatrices located on the diagonal of the block diagonal matrix. An intermediate vector is generated based on the information data bits and the first matrix, and a parity vector of a codeword is generated based on the intermediate vector and the second matrix.