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

• US 5,737,416 A
• Filed: 08/02/1996
• Issued: 04/07/1998
• Est. Priority Date: 04/25/1994
• Status: Expired due to Term

• Current Assignee: Activision Publishing Incorporated (Microsoft Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Cooper, Thomas Edward, Phillips, Hudson Wayne, Pryor, Robert Franklin
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US08/693,555
• Time in Patent Office: 613 Days
• Field of Search: 380/4, 380/9, 380/21, 380/23, 380/25, 380/49, 380/50, 395/601, 395/616, 395/186, 395/427, 395/481, 395/490, 395/491, 395/726, 395/728
• US Class Current: 705/52
• CPC Class Codes: G06F 21/1063 Personalisation
• CPC Class Codes: G06F 21/121 Restricting unauthorised execution of programs
• CPC Class Codes: G06F 21/126 Interacting with the operating system
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress

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. At least one encrypted file and at least one unencrypted file are stored in the computer-accessible memory media. An unencrypted security stub is associated with each of the encrypted files. The security stub is at least partially composed of executable code. The file management program is utilized to monitor data processing calls for a called file stored in the computer-accessible memory media. The file management program determines what the called file has an associated unencrypted security stub. The called file is processed in a particular manner dependent upon whether or not the called file has an associated unencrypted security stub.

Claims

1. A method of allowing selective access to an encrypted file, comprising the method steps of:

providing a plurality of files, the encrypted file being one of the plurality of files;

attaching an unencrypted security stub, at least partially composed of executable code, to the encrypted file;

locating the plurality of files in an accessible location;

generating a user-initiated request for a called file in response to an action taken by a user, the called file being one of the plurality of files;

translating the user request into a data processing system call;

receiving the data processing system call using a file management program, wherein the file management program exists in (a) an active state or (b) an inactive state, the file management program being a component of an operating system;

selectively accessing the called file from among the plurality of files utilizing the file management program, if the called file has the unencrypted security stub;

accessing the called file from among the plurality of files utilizing the file management program, if the called file does not have the unencrypted security stub;

processing the called file in accordance with the user-initiated request, to the extent the called file was accessed, wherein access by the user to the certain ones of the plurality of files is controlled by the unencrypted security stub.

2. A method according to claim 1, wherein the steps of selectively accessing and accessing the called file utilizing the file management program further comprise:

examining at least a portion of the called file.

3. A method according to claim 1, wherein the steps of selectively accessing and accessing the called file utilizing the file management program further comprise:

if it is determined that the called file has the attached unencrypted security stub, analyzing the attached unencrypted security stub to obtain information for utilization in decryption operations.

4. A method according to claim 1, further comprising:

if it is determined that the called file has no the attached unencrypted security stub, allowing the called file to be processed;

if it is determined that the called file has the attached unencrypted security stub;

(a) examining at least one of (1) the called file and (2) the attached unencrypted security stub, in order to obtain information which allows decryption operations to be performed;

(b) decrypting the called file; and

(c) allowing processing of the called file.

5. A method according to claim 1, further comprising:

if it is determined that the called file has the attached unencrypted security stub, decrypting the called file at the same time as it is passed for further processing.

6. A method according to claim 1, further comprising:

if the file management program is in the active state and if the called file has the unencrypted security stub, separating the attached unencrypted security stub from the called file prior to processing the called file;

if the file management program is in the inactive state and if the attached unencrypted security stub is determined to exist;

(a) preventing the processing of the called file;

(b) notifying the user of inability to execute the called file.

7. A method according to claim 1:

wherein the at least one encrypted file comprises at least one encrypted software product, which may be decrypted with a short-lived key.

8. A method according to claim 7, wherein the short-lived key may be used to enable the software product for a particular customer trial interval.

9. A method according to claim 8, further comprising:

utilizing the file management program to interact with the short-lived key to modify the particular customer trial interval for the software product.

10. A method according to claim 8, further comprising:

locating the short-lived key in a particular file paired with the called file;

utilizing the file management program to search for the short-lived key in the particular file paired with the called file.

11. A method according to claim 7:

wherein the particular customer trial interval comprises at least one of;

(a) a predefined time interval; and

(b) a predefined number of processing calls.

12. An apparatus for allowing selective access to an encrypted file, comprising:

means for providing a plurality of files, the encrypted file being one of the plurality of files;

means for attaching an unencrypted security stub, at least partially composed of executable code, to the encrypted file;

means for locating the plurality of files in an accessible location;

means for generating a user-initiated request for a called file in response to an action taken by a user, the called file being one of the plurality of files;

means for translating the user request into a data processing system call;

means for receiving the data processing system call using a file management program, wherein the file management program exists in (a) an active state or (b) an inactive state, the file management program being a component of an operating system;

means for selectively accessing the called file from among the plurality of files utilizing the file management program, if the called file is has the unencrypted security stub;

means for accessing the called file from among the plurality of files utilizing the file management program, if the called file does not have the unencrypted security stub;

means for processing the called file in accordance with the user-initiated request, to the extent the called file was accessed, wherein access by the user to the certain ones of the plurality of files is controlled by the unencrypted security stub.

13. An apparatus according to claim 12, wherein the file management program includes:

means for examining at least a portion of the called file.

15. An apparatus according to claim 12, wherein the file management program is operable in a plurality of operating modes, including:

a pass-through mode of operation if it is determined that the called file has no attached unencrypted security stub, by allowing the called file to be processed;

a decryption mode of operation if it is determined that the called file has an attached unencrypted security stub by;

(a) examining at least one of (1) the called file and (2) the unencrypted security stub, to obtain information which allows decryption operations to be performed;

(b) decrypting the called file; and

(c) allowing processing of the called file.

16. An apparatus according to claim 12, further comprising:

means for decrypting the called file at the same time as it is passed for further processing.

17. An apparatus according to claim 12, wherein the file management program is further utilized to:

if the file management program is in the active state, and if the attached unencrypted security stub is determined to exist, separate the attached unencrypted security stub from the called file prior to execution of the called file;

if the file management program is in the inactive state, and if the attached unencrypted security stub remains attached to the called file;

(a) prevent execution of the called file; and

(b) post a message in the data processing system advising of inability to execute the called file.

18. An apparatus according to claim 12:

wherein the at least one encrypted file comprises at least one encrypted software product, which may be decrypted with a short-lived key.

19. An apparatus according to claim 18, wherein the short-lived key defines a particular customer trial interval for the software product.

20. An apparatus according to claim 19, further comprising:

means for utilizing the file management program to interact with the short-lived key to modify the particular customer trial interval for the software product.

21. An apparatus according to claim 19, further comprising:

means for locating the short-lived key in a particular location relative to the called file;

means for utilizing the file management program to search for the short-lived key in the particular location relative to the called file.

22. An apparatus according to claim 18:

wherein the particular customer trial interval comprises at least one of;

(a) a predefined time interval; and

(b) a predefined number of processing calls.

14. An apparatus according to claim 38, wherein the file management program further includes:

means for analyzing the attached unencrypted security stub to obtain information for utilization in decryption operations.