The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 18, 2007
Filed:
Mar. 05, 2002
Minoru Sasaki, Tokyo, JP;
Minoru Sasaki, Tokyo, JP;
Pumpkin House Incorporated, Tokyo, JP;
Abstract
To provide a cryptographic system capable of flexibly changing decryption authorization and preventing the action of a third person impersonating a user having the decryption authorization to improperly utilize the system. When an enciphered file is accepted in a client, a decryptor ID, a creator ID, and a first enciphered session key are transmitted to a key management server(step). It is judged whether or not the creator ID is stored as a decryption object ID in a management database in correspondence with the decryptor ID (step). When the creator ID is stored, the first enciphered session key is deciphered with an inherent key corresponding to the creator ID in the management database (step), and the obtained session key is enciphered with a public key corresponding to the decryptor ID (step). A secret key is used in a client which has received a second enciphered session key so that deciphering processing is performed, to obtain a session key. Enciphered data is deciphered with the session key.