Obfuscation of automatically generated code

• US 7,689,969 B1
• Filed: 01/18/2005
• Issued: 03/30/2010
• Est. Priority Date: 01/18/2005
• Status: Active Grant

• Current Assignee: The MathWorks, Inc.
• Original Assignee: The MathWorks, Inc.
• Inventors: Wendling, Bill
• Primary Examiner(s): DENG, ANNA CHEN
• Application Number:
  US11/038,608
• Time in Patent Office: 1,897 Days
• Field of Search: 717104-109, 717/118, 717/140, 717/145, 717/148, 715/700, 715762-764, 713189-193
• US Class Current: 717/105
• CPC Class Codes: G06F 21/1066 Hiding content
• CPC Class Codes: G06F 21/14 against software analysis or reverse engineering, e.g. by obfuscation
• CPC Class Codes: G06F 8/34 Graphical or visual programming

Abstract

A method is provided for obfuscating code generated from a block diagram model in a graphical programming environment. The obfuscation may be removed through the use of a password. Incorporating the obfuscated code in a block diagram allows for code to be generated from the block diagram incorporating the obfuscated code.

Claims

1. In a graphical programming environment, a computer-implemented method comprising:

providing a block diagram model of a dynamic system in the graphical programming environment executing on a computing device;

generating source code from the block diagram model in the graphical programming environment;

converting the generated source code to obfuscated source code, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the generated source code;

converting strings to a different number system; and

applying a one-way hash function to the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation;

obfuscating related files necessary to compile the obfuscated source code; and

compiling the obfuscated source code.

2. The method of claim 1, further comprising incorporating the obfuscated source code into the block diagram model.

3. The method of claim 2, further comprising:

generating source code form the block diagram model incorporating the obfuscated source code.

4. The method of claim 1, wherein the graphical programming environment is a block diagram environment.

5. The method of claim 1, wherein the generating the source code further comprises:

gathering all required libraries in a first directory;

generating the source code in the first directory; and

converting the source code in the first directory to the obfuscated code in a second directory.

6. The method of claim 1 wherein the converting the generated source code to the obfuscated code further comprises converting files containing functionality as well as non-system interface files required by the functionality files.

7. The method of claim 6 wherein the functionality files are C text files and the interfaces are header files.

8. The method of claim 1, wherein the converting the generated source code to the obfuscated code further comprises:

renaming non-system header files; and

replacing numeric constants with obfuscated names.

9. The method of claim 8 further comprising removing loops from the generated source code.

10. The method of claim 1 wherein the one-way hash function is MD5.

11. The method of claim 1 wherein the different number system is base 8.

12. The method of claim 1 wherein the different number system is base 16.

13. A computer-implemented method, comprising:

providing a block diagram model of a dynamic system in a graphical programming environment executing on a computing device;

generating source code from the block diagram model in the graphical programming environment;

converting a portion of the generated source code to obfuscated source, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the portion of the generated source code;

converting strings to a different number system in the portion of the generated source code; and

applying a one-way hash function to the portion of the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation;

obfuscating related files necessary to compile the obfuscated source code; and

compiling the obfuscated source code.

14. The method of claim 13, wherein the portion of the generated source code that is obfuscated is selected based on user interaction.

15. The method of claim 13, wherein a select subset of files necessary for compiling source code are also obfuscated.

16. The method of claim 15, wherein the subset is automatically determined based on the functional criteria.

17. A computer implemented method in a graphical programming environment comprising:

providing a block diagram model of a dynamic system in the graphical programming environment executing on a computing device;

selecting a target code generator that generates source code for a target environment;

generating the source code from the block diagram model in the graphical programming environment using the target code generator;

converting the generated source code to obfuscated source code, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the generated source code;

converting strings to a different number system; and

applying a one-way hash function to the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation;

obfuscating related files necessary to compile the obfuscated source code; and

compiling the obfuscated source code.

18. The method of claim 17 wherein the target code generator is selected using a graphical interface.

19. The method of claim 17, wherein the target code generator generates source for an S-function block.

20. A system for generating and displaying a graphical modeling application, comprising:

a distribution server for providing to a client device obfuscated source code, the distribution server is capable of;

providing a block diagram model;

generating source code from the block diagram model;

converting the generated source code to obfuscated source code, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the generated source code;

converting strings to a different number system; and

applying a one-way hash function to the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation; and

obfuscating related files necessary to compile the obfuscated source code;

the client device in communication with the distribution server, wherein the client device is an electronic device.

21. In a network having a server, executing a graphical modeling environment, and a client device in communication with the server, a method comprising:

providing, at the server, a block diagram model of a dynamic system;

receiving, at the server from the client device, a request to generate obfuscated source code;

generating, at the server, source code from the block diagram model in the graphical modeling environment;

converting, at the server, the generated source code to obfuscated source code, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the generated source code;

converting strings to a different number system; and

applying a one-way hash function to the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation;

obfuscating, at the server, related files necessary to compile the obfuscated source code; and

transmitting to the client device from the server the obfuscated source code and obfuscated related files.

22. A computer-readable storage medium holding instructions, the instructions when executed causing a computing device to:

provide a block diagram model of a dynamic system in a graphical programming environment;

generate source code from the block diagram model in the graphical programming environment;

convert the generated source code to obfuscated source code, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the generated source code;

converting strings to a different number system; and

applying a one-way hash function to the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation;

obfuscate related files necessary to compile the obfuscated source code; and

compile the obfuscated source code.

23. A system for generating and displaying a graphical modeling application, comprising:

user-operable input means for inputting data to the graphical modeling application executing in a graphical modeling environment;

a display device for displaying a graphical model; and

an electronic device including memory for storing computer program instructions and data, and a processor for executing the stored computer program instructions, the computer program instructions including instructions for;

providing a block diagram model of a dynamic system;

generating source code from the block diagram model in the graphical modeling environment;

converting the generated source code to obfuscated source code, the obfuscated source code automatically selected based on functional criteria of the block diagram model or functional criteria of the generated source code, the functional criteria including semantic and syntactic notions that affect execution and editing of the block diagram model or the generation of the source code, wherein the converting includes;

removing comments and formatting from the generated source code;

converting strings to a different number system; and

applying a one-way hash function to the generated source code;

wherein the obfuscation is deterministic and a provided password is capable of breaking the determinism of the obfuscation;

obfuscating related files necessary to compile the obfuscated source code; and

compiling the obfuscated source code.