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:
Oct. 13, 2009
Filed:
Jun. 14, 2004
Yuichi Futa, Osaka, JP;
Masato Yamamichi, Ota, JP;
Masami Yamamichi, Legal Representative, Ota, JP;
Satomi Yamamichi, Legal Representative, Ota, JP;
Keiko Yamamichi, Legal Representative, Maebashi, JP;
Motoji Ohmori, Hirakata, JP;
Makoto Tatebayashi, Takarazuka, JP;
Yuichi Futa, Osaka, JP;
Masato Yamamichi, Ota, JP;
Masami Yamamichi, legal representative, Ota, JP;
Satomi Yamamichi, legal representative, Ota, JP;
Keiko Yamamichi, legal representative, Maebashi, JP;
Motoji Ohmori, Hirakata, JP;
Makoto Tatebayashi, Takarazuka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An encryption transmission apparatus and an encryption reception apparatus avoid attack that takes advantage of a re-transmission request. A server apparatus encrypts a content key five times, thereby generating five encrypted content keys, calculates a hash value of the content key, and transmits the five encrypted content keys and the hash value. An image playback apparatus receives the five encrypted content keys and the hash value, decrypts the five encrypted content keys thereby generating five content keys, calculates hash values, each corresponding to the generated content keys, and compares the calculated hash values with the received hash value, respectively. If at least one of the five calculated hash values matches the received hash value, the corresponding content key is considered correct. Conversely, if none of the five calculated hash values matches the received hash value, it is considered a decryption error.