1. A protection key for hardware comprising: a first storage area configured to store a key data used for permission to use software installed in an information processor; a second storage area configured to store a data table including a plurality of random numbers; a receiver configured to receive a cryptography key from the information processor; a coder/decoder configured to encrypt the key data based on the cryptography key by picking one random number from the data table; and a transmitter configured to transmit the encrypted key data to the information processor.