DIGITAL SIGNAL RECORDER WITH SELECTIVE ENCRYPTION AND KEY GENERATION

• US 20080317436A1
• Filed: 09/02/2008
• Published: 12/25/2008
• Est. Priority Date: 02/26/1999
• Status: Abandoned Application

• Current Assignee: Hiroo Okamoto, Makoto Aikawa, Manabu Sasamoto, Takaharu Noguchi
• Original Assignee: Hiroo Okamoto, Makoto Aikawa, Manabu Sasamoto, Takaharu Noguchi
• Inventors: OKAMOTO, Hiroo, SASAMOTO, Manabu, AIKAWA, Makoto, NOGUCHI, Takaharu
• Application Number:
  US12/202,587
• Publication Number:
  US 20080317436A1
• Time in Patent Office: Days
• US Class Current: 386/95
• CPC Class Codes: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
• CPC Class Codes: G11B 20/0021 involving encryption or decryption of contents recorded on or reproduced from a record carrier
• CPC Class Codes: G11B 20/00478 wherein contents are decrypted and re-encrypted with a different key when being copied from/to a record carrier
• CPC Class Codes: G11B 20/00507 wherein consecutive physical data units of the record carrier are encrypted with separate encryption keys, e.g. the key changes on a cluster or sector basis
• CPC Class Codes: G11B 2220/90 Tape-like record carriers
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/4334 Recording operations recording of a television signal H04N5/76; arrangements for recording or accumulating broadcast information or broadcast-related information H04H60/27
• CPC Class Codes: H04N 21/44055 by partially decrypting, e.g. decrypting a video stream that has been partially encrypted
• CPC Class Codes: H04N 21/4408 involving video stream encryption, e.g. re-encrypting a decrypted video stream for redistribution in a home network
• CPC Class Codes: H04N 5/78263 for recording on tracks inclined relative to the direction of movement of the tape
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 9/8042 involving data reduction

Abstract

A digital signal recorder for recording a digital signal on a recording medium, including: an input circuit which receives a transmitted digital signal encrypted for protecting said transmitted digital signal using a first encryption method; a decrypting circuit which decrypts said transmitted digital signal into an original data; a key generation circuit which performs a prescribed arithmetic operation to generate a key; an encrypting circuit which receives said key and said original data, and encrypts said original data with said key using a second encryption method; a recording circuit which records, onto said recording medium, a key information which is used for decrypting said encrypted digital signal together with said encrypted digital signal, and a timing control circuit which controls decrypting timing of said decrypting circuit and encryption timing of said encrypting circuit; wherein said key generation circuit has a function for updating said key in connection with recording units of said recording media.

Claims

1. A digital signal recorder for recording a digital signal on a recording medium, comprising:

an input circuit which receives a transmitted digital signal encrypted for protecting said transmitted digital signal using a first encryption method;

a decrypting circuit which decrypts said transmitted digital signal into an original data;

a key generation circuit which performs a prescribed arithmetic operation to generate a key;

an encrypting circuit which receives said key and said original data, and encrypts said original data with said key using a second encryption method;

a recording circuit which records, onto said recording medium, a key information which is used for decrypting said encrypted digital signal together with said encrypted digital signal, and

a timing control circuit which controls decrypting timing of said decrypting circuit and encryption timing of said encrypting circuit;

wherein said key generation circuit has a function for updating said key in connection with recording units of said recording media.

2. The digital signal recorder according to claim 1,

said key generation circuit has a function for updating said key at a prescribed length interval.

3. The digital signal recorder according to claim 2, wherein:

said digital signal has a packet format of a prescribed length; and

said recording circuit has a function for adding identifying information indicating where said key is updated, to packets of said digital signal recorded on said recording medium.

4. The digital signal recorder according to claim 3, wherein:

said recording circuit has a function for adding encryption flag information indicating whether said digital signal is encrypted or not, to packets of said digital signal recorded on said recording medium.

5. The digital signal recorder according to claim 3, wherein:

said recording medium is a removable recording medium.