Patent ID: 8140858

Claim:
A data processing apparatus comprising: a security unit having an encryption means operable to decode an encrypted signal including secrecy data, wherein the security unit includes: a compression means operable to compress an access signal to be used in accessing the security unit to output the compression result; and a comparison means operable to compare the compression result outputted by the compression means with a previously-obtained expectation value of the compression result of the access signal, wherein, when the compression result and the expectation value are different as the result of comparison by the comparison means, one of nullifying output of a signal decrypted by the encryption means and notifying the result of the comparison concerned is performed, wherein the encrypted signal includes a program to control the security unit, and wherein, when the program includes a processing accompanied by a conditional branch, a correction value is inputted to the compression means so as to make the compression result same when joined after the conditional branch.