XOR two blocks of data. Each block must be a hex representation of binary data, e.g. b'DF1267EEDCBA9876'

def xor(block1, block2):
    """
    XOR two blocks of data. Each block must be a hex representation of binary data, e.g. b'DF1267EEDCBA9876'
    """
    xored = ''.join(['{0:#0{1}x}'.format((i ^ j), 4)[2:] for i, j in zip(B2raw(block1), B2raw(block2))])
    return bytes(xored.upper(), 'utf-8')