def extend_round_key(cipher_matrix, rounds):
	rcon = [['01','00','00','00'],
		['02','00','00','00'],
		['04','00','00','00'],
		['08','00','00','00'],
		['10','00','00','00'],
		['20','00','00','00'],
		['40','00','00','00'],
		['80','00','00','00'],
		['1B','00','00','00'],
		['36','00','00','00']]
	extended_round_key = cipher_matrix.copy() # copy the provided key to extend
	for extension in range(rounds): # perform an extension for each round
		for j in range(len(extended_round_key)): # do this four times
			for i in range(len(extended_round_key)): # do this four times
				if (len(extended_round_key[i]) % 4 == 0): # if the new position is evenly divisible by 4 do the complicated thing
					extended_round_key[i] += [bin_to_hex(xor(xor((''.join(byte_substitution(hex_to_bin(extended_round_key[(i+1)%len(extended_round_key)][len(extended_round_key[i])-1])))),hex_to_bin(extended_round_key[i][-4])),hex_to_bin(rcon[extension][i])))]
				else: # otherwise do the simple thing
					extended_round_key[i] += [bin_to_hex(xor(hex_to_bin(extended_round_key[i][-1]), hex_to_bin(extended_round_key[i][-4])))]
	return extended_round_key # return the extended key