Patent ID: 6560339
Filing Date: 2003-05-06
Classification: H04N

Abstract:
An information processing method comprising:a first step of dividing digital data into a plurality of pieces and generating a plurality of pieces of encrypted digital data by encrypting each of the plurality of pieces of digital data using each respective one of a provider's encryption keys; a second step of generating a first set of encrypted provider encryption keys by multiplying at least one of the provider's encryption keys by a random number and encrypting the result; a third step of generating a second set of encrypted provider encryption keys by encrypting at least one of the provider's encryption keys, the first to third steps being executed by a provider apparatus; a fourth step of selecting at least one pair comprising a member of the second set of encrypted provider encryption key and a corresponding a piece of encrypted digital data; and a fifth step of generating a first set of double encrypted encryption keys by respectively encrypting each member of the first set of encrypted provider encryption keys and a second set of double encrypted encryption keys by respectively encrypting each member of the second set of encrypted provider encryption keys selected in the fourth step, the fourth and fifth steps being executed by a user apparatus, wherein the first set of double encrypted provider encryption keys and the second set of double encrypted provider encryption keys are decrypted and used to generate a third encrypted encryption key and a fourth encrypted encryption key by said provider apparatus.