Patent ID: 7930759

Claim:
A backup system for an image forming apparatus comprising: the image forming apparatus including an original data storage unit configured to store data, the image forming apparatus sending a backup copy of the data; and a backup apparatus electrically communicating with the image forming apparatus, the backup apparatus including a backup copy storage unit configured to save the backup copy received from the image forming apparatus, wherein the image forming apparatus further includes: a key generation unit configured to uniquely generate a key from an input key seed; an encryption and decryption unit configured to execute an encryption process and a decryption process in a symmetric-key cryptosystem using the key generated from the key seed by the key generation unit; and a nonvolatile memory unit configured to pre-store a first key seed, and the backup apparatus further includes: a nonvolatile memory unit configured to pre-store a second key seed, wherein the data stored in the original data storage unit is data encrypted in the cryptosystem using a first key generated from the first key seed by the key generation unit and stored in the original data storage unit, the key generation unit of the image forming apparatus generates a second key from a copy of the second key seed received from the backup apparatus, the encryption and decryption unit of the image forming apparatus performs double encryption by further encrypting the backup copy of at least a part of the data stored in the original data storage unit in the cryptosystem using the second key, and encrypts a copy of the first key seed in the cryptosystem using the second key, and the backup copy storage unit of the backup apparatus stores the double-encrypted backup copy received from the image forming apparatus and the copy of the first key seed encrypted in the cryptosystem using the second key.