Other

Seiko Kanno

Naoya Torii

Kazue Sako

Hiroshi Miyauchi

Yasutsugu Kuroda

Seiichi Domyo

Hiroyuki Ando

Hiroyoshi Tsuchiya

Masashi Yamazaki

Ichirou Morita

Ichir{overscore (o)}u M{overscore (o)}rita

A key recovery condition encryption apparatus includes a hashing unit, a first concatenating unit, and a condition information encryption unit. The hashing unit calculates a hash value on the basis of a hash function using a key recovery information text serving as information necessary for performing key recovery. The first concatenating unit concatenates the hash value from the hashing unit to the key recovery condition. The condition information encryption unit encrypts a concatenating result from the first concatenating unit by using a first encryption key. Also is disclosed a key recovery condition decryption apparatus for decrypting the encrypted data from the above encryption apparatus.

Key recovery condition encryption and decryption apparatuses

The present invention has an object to overcome problems of a key recovery system using a conventional KRF system and to achieve efficient operation of the overall key recovery system. A key recovery system of the present invention includes check units,for checking whether a user has a recovery authorization for a common key KS, on the basis of a recovery condition RC specified by a recovery condition index RCI which is added to an encrypted message (encrypted message obtained by encrypting the common key KS with a public key KRCpub) supplied from a terminal (,to,) of the user concerned, and a key recovery control unit,which is provided separately from the check units,and decrypts the encrypted message with a private key KRCpri paired with the public key KRCpub to recover the common key. The check unit,supplies the common key KS recovered in the key recovery control unit,to the user concerned only when the user has the recovery authorization.

Key recovery system and key recovery method

A key recovery information distribution device is provided between a recoverer device and a key recovery device, recovers a data key for the recoverer device, and reduces the load of the recoverer device. Data is encrypted using the data key and stored with key recovery information. The recoverer device which decrypts the encrypted data distributes the key recovery information to key recovery devices through the key recovery information distribution device to recover key information. A recoverer is authenticated directly between the key recovery device and the recoverer device, and then the key information is transmitted to the recoverer device, and the recoverer device recovers the data key.

Key recovery system

Growing community of inventors

Yokohama, Japan

Seiko Kanno