Method and apparatus for enabling trial period use of software products: Method and apparatus for utilizing a decryption block

Patent 5598470 Issued on January 28, 1997. Estimated Expiration Date:

April 25, 2014. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Cryptographic labeling of electronically stored data
Patent #: 4864616
Issued on: 09/05/1989
Inventor: Pond , et al.

Modular software security
Patent #: 4888798
Issued on: 12/19/1989
Inventor: Earnest

Test automation system
Patent #: 5021997
Issued on: 06/04/1991
Inventor: Archie, et al.

Method and apparatus for updating software at remote locations
Patent #: 5155847
Issued on: 10/13/1992
Inventor: Kirouac, et al.

System to demonstrate and sell computer programs
Patent #: 5166886
Issued on: 11/24/1992
Inventor: Molnar, et al.

Transformation of ephemeral material Patent #: 5341429
Issued on: 08/23/1994
Inventor: Stringer, et al.

Inventors

Application

No. 235031 filed on 04/25/1994

US Classes:

713/165, File protection705/51Usage protection of distributed data files

Examiners

Primary: Gregory, Bernarr E.

Attorney, Agent or Firm

Duffield; Edward H., Bumgardner; Barry J., Dillon; Andrew J.

Foreign Patent References

0268139A2 EP 05/13/1988
0268139A3 EP 05/13/1988
0561685A3 EP 09/13/1993
0561685A2 EP 09/13/1993
0598587A1 EP 05/13/1994
0601500A1 EP 06/13/1994
2136175 GB 09/13/1984
WO94/07204 WO 03/13/1994

International Classes

H04L 009/32
H04L 009/00

Abstract

A method and apparatus is provided in a data processing system for securing access to particular files which are stored in a computer-accessible memory media. A file management program is provided as an operating system component of the data processing system. A plurality of files are stored in a computer-accessible memory media, including at least one encrypted file and at least one unencrypted file. For each encrypted file, a preselected portion of the file is recorded in memory, a decryption block is generated which includes information which can be utilized to decrypt the file, and the decryption block is incorporated in the file in lieu of the preselected portion which has been recorded in memory. Then, a file management program is utilized to monitor data processing system calls for files stored in the computer-accessible memory media. The file management program determines whether the called file has an associated decryption block. The called file is processed in a particular manner dependent upon whether or not the called file has an associated decryption block.

Other References

"Data Masking Algorithm" (IBM Technical Disclosure Bulletin, vol. 32 No. 68, Nov. 1989)
"Information Distribution via Rom Disks" (IBM Technical Disclosure Bullletin, vol. 33 No. 12, May 1991