An apparatus for polar coding includes an encoder circuit that implements a transformation c=u1N-sBN-s{tilde over (M)}n, where u1N-s, BN-s, {tilde over (M)}n, and C are defined over a Galois field GF(2k), k>1, N=2k, s<N, u1N-s=(u1, . . . , uN-s) is an input vector of N-s symbols over GF(2k), BN-s is a permutation matrix, {tilde over (M)}n=((N−s) rows of Mn=), the matrix M1 is a pre-defined matrix of size q×q, 2<q, N=qn and n≥1, and C is a codeword vector of N-s symbols. A decoding complexity of C is proportional to a number of symbols in C. The apparatus further includes a transmitter circuit that transmits codeword C over a transmission channel.