Patent ID: 8331562

Claim:
An image forming apparatus comprising: an output part that outputs variable information varying in a time-dependent manner in the image forming apparatus; a first encrypt part that encrypts the variable information outputted from the output part using a first encrypt key read out from a memory; a second encrypt key create part that creates a second encrypt key according to the variable information outputted from the output part; a second encrypt part that encrypts inherent information for specifying the image forming apparatus using the second encrypt key created by the second encrypt key create part; a generate part that generates code data according to the variable information encrypted in the first encrypt part and the inherent information encrypted in the second encrypt part; and an image form part that forms on a recording member a code image based on the code data generated in the generate part, wherein the output part outputs, as the variable information to be encrypted by the first encrypt part and used for the creation of the second encrypt key.