Digital data file encryption apparatus and method and recording medium for ...

5,323,464 A 5,539,827 A

6/1994 Elanderetal. 7/1996 Liu

713/191

(Continued) FOREIGN PATENT DOCUMENTS

OTHER PUBLICATIONS

Lacy, J. et al., "Music on the Internet and the Intellectual Property Protection Problem", ISIE '97, Guimaraes, Portugal, pp. SS77-SS83.

Business Wire, "J-Bird Records Becomes First Label to Launch a CO-Branded Download Station with AT&T's a 2b music; Site Allows sampling and Purchase of CD-quality Downloads", Business Wire, New York: Jan. 19, 1999.

Primary Examiner—Ponnoreay Pich

(74) Attorney, Agent, or Firm—Birch, Stewart, Kolasch & Birch, LLP

A digital data file encryption system and method where digital data encrypted to a high level and an encryption key are received and stored in a computer. The stored, encrypted digital data is decrypted on the basis of the encryption key and stored in a buffer of a predetermined size. Output digital data from the buffer is reencrypted to a low level of encryption and downloaded to a digital data playing device or a data storage medium. Therefore, a digital audio or video data file is prevented from being diverted in unencrypted form from a computer communication network when it is transmitted to a personal computer through the computer communication network and, in turn, downloaded to the digital data playing device. Further, the digital data playing device is prevented from rising in cost due to the use of simple encryption for data downloaded to the playing device.

6 Claims, 6 Drawing Sheets

Page 2

U.S. PATENT DOCUMENTS

5,659,618 A 8/1997 Takahashi et al.

5,867,579 A 2/1999 Saitoetal.

5,889,860 A 3/1999 Elleretal.

5,917,915 A * 6/1999 Hirose 380/228

5,991,399 A * 11/1999 Graunke et al 380/279

5,999,622 A 12/1999 Yasukawa et al.

6,003,135 A 12/1999 Bialicketal.

6,021,199 A * 2/2000 Ishibashi 380/217

6,170,060 Bl * 1/2001 Mottetal 726/29

6,289,454 Bl * 9/2001 Eslingeretal 713/189

Wiser et al.

Ansell et al 726/26

Wiser et al.

Elgamal etal 713/164

Bharat
Kato et al.
Lee et al.

Boccon-Gibod et al 705/51

Shear et al.
Ireton

Krishnan et al.