private static byte[][] ShiftRows(byte[][] state) {

		byte[] t = new byte[4];
		for (int r = 1; r < 4; r++) {
			for (int c = 0; c < Nb; c++)
				t[c] = state[r][(c + r) % Nb];
			for (int c = 0; c < Nb; c++)
				state[r][c] = t[c];
		}

		return state;
	}