To dispense with authentication between a secure device and digital content decoding software in an information processor (a personal computer, for example) having a digital content receipt function to prevent cracking of the digital content decoding software and a common key due to authentication behavior of the digital content decoding software for improving protection for digital contents.

Secure hardware 29 sets the common key used for encryption of the digital content, which is outputted by an OFDM demodulator 28 or read from a hard disk 25 to be decoded, in a key area 36 of secure software 35. The secure software 35 makes a computer operate a decoding process, which is carried out by using the common key set in the key area 36, of the digital content encrypted by the secure hardware 29.