I assume you want to populate your [b]key[b] array at the top of the j
loop starting at line 19?
is the key round?
If so, you might try inserting this right after line 20
for (int bit = 0; (8 > bit); bit ++)
key[j][bit] = block[bit];
Also, there's a really good essay on arrays at this C topic: Arrays Revealed