公开(公告)号：EP1612990A4

公开(公告)日：2011-06-01

申请号：EP04719621

申请日：2004-03-11

Applicant: PANASONIC CORP

Inventor： FUTA YUICHI ,  OHMORI MOTOJI ,  YAMAMOTO MASAYA ,  TATEBAYASHI MAKOTO ,  YAMAMICHI MASATO

IPC: G11B20/00 ,  G06F12/14 ,  G06F15/00 ,  G11B20/10 ,  H04L9/08 ,  H04L9/32

CPC classification number: H04N21/4325 ,  G11B20/00086 ,  G11B20/00173 ,  G11B20/0021 ,  G11B20/00246 ,  G11B20/00362 ,  G11B20/00492 ,  H04N21/26613 ,  H04N21/835

公开(公告)号：EP1624608A4

公开(公告)日：2011-08-17

申请号：EP04719578

申请日：2004-03-11

Applicant: PANASONIC CORP

Inventor： NAKANO TOSHIHISA ,  FUTA YUICHI ,  OHMORI MOTOJI ,  TATEBAYASHI MAKOTO ,  HARADA SHUNJI ,  MURASE KAORU ,  YAMAMICHI MASATO

IPC: H04L9/08 ,  G11B20/00 ,  H04L9/32

CPC classification number: H04L9/0822 ,  G11B20/00086 ,  G11B20/00253 ,  H04L9/3268 ,  H04L2209/60

Abstract: The invention provides a recording apparatus and a reproduction apparatus that are able to prevent illegitimate use of contents. A recording medium stores therein a medium inherent number in the unrewritable area. The recording apparatus writes media key data and an encrypted content onto the recording medium. The media key data includes encrypted media keys generated by (i) for each of unrevoked reproduction apparatuses, encrypting a media key using a device key of the unrevoked reproduction apparatus respectively, and (ii) for each of revoked reproduction apparatuses, encrypting detection information using a device key of the revoked reproduction apparatus respectively. The reproduction apparatus decrypts the encrypted media key using a device key to generate a decryption media key, judges whether the decryption media key is the detection information or not, and prohibits the encrypted content recorded on the recording medium from being decrypted when having judged in the affirmative.

公开(公告)号：EP1732052A4

公开(公告)日：2009-07-08

申请号：EP05727024

申请日：2005-03-22

Applicant: PANASONIC CORP

Inventor： FUTA YUICHI ,  OHMORI MOTOJI ,  SHIZUYA HIROYUKI ,  MAMBO MASAHIRO ,  YAMAMICHI MASATO

IPC: G06F7/72 ,  G06F7/50 ,  G09C1/00

CPC classification number: G06F7/72 ,  G06F7/723

Abstract: There is provided a computer system which makes it difficult to analyze a calculation content. A power calculation unit (262) performs the following calculation for the input data "a" and "b": ga = g mod n, gb = g mod n. Next, a multiplication unit (264) performs the following calculation for ga and gb: gab = ga x gb mod n. Next, a discrete logarithm calculation unit (266) calculates ci mod pi - 1 which satisfies gab = g mod pi (i = 1, 2, ..., k). Next, a CRT unit (267) calculates "c" which satisfies ci = c mod pi - 1 (i = 1, 2, ..., k) by the Chinese remainder theorem (CRT).