Patent ID: 7526656

Claim:
An encryption/decryption system comprising: a mobile first decryption apparatus that includes: a first decryption unit that decrypts supplied first encrypted data with a private key of the mobile first decryption apparatus to obtain an encryption/decryption key, and a third decryption unit that (1) decrypts supplied third encrypted data with the private key of the mobile first decryption apparatus, so as to obtain decrypted given data, and (2) supplies a second decryption apparatus with the decrypted given data; an encryption apparatus that includes: a first encryption unit that encrypts target data with the encryption/decryption key to generate second encrypted data, a second encryption unit that encrypts the encryption/decryption key with a public key of the mobile first decryption apparatus to generate the first encrypted data, the encryption/decryption key used to encrypt data and to decrypt encrypted data, and an association unit that associates the first encrypted data, the second encrypted data, and the public key of the mobile first decryption apparatus with each other; and the second decryption apparatus that includes: a reception unit that receives the first encrypted data, the second encrypted data, and the public key of the mobile first decryption apparatus associated with each other from the encryption apparatus, the public key received by the reception unit being unencrypted, a second decryption unit that decrypts the received second encrypted data into the target data by using the encryption/decryption key, a first encrypted data supply unit that (1) receives from the mobile first decryption apparatus the public key of the mobile first decryption apparatus, and (2) supplies the mobile first decryption apparatus with the first encrypted data which is associated with a public key that is identical to the public key received from the mobile first decryption apparatus, a third encryption unit that (1) encrypts given data with the public key of the mobile first decryption apparatus received from the encryption apparatus so as to generate the third encrypted data, and (2) supplies the mobile first decryption apparatus with the third encrypted data, and a second encrypted data supply unit that supplies the mobile first decryption apparatus with the first encrypted data, which correspond to the supplied public key of the mobile first decryption apparatus, in accordance with the supplied decrypted given data, wherein the mobile first decryption apparatus transmits the encryption/decryption key to the second decryption apparatus, and the second decryption unit decrypts the received second encrypted data into the target data by using the received encryption/decryption key.