HDLObf_reference_guide HDLObf Reference Guide

HDLObf_reference_guide

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HDL Obfuscator and Name Change Tool
Reference Guide
Technical Support:
Website: https://sourceforge.net/projects/hdlobf/
Email: vispicassod@hotmail.com
Trademark:
Verilog® is a registered trademark of Cadence Design Systems, Inc.
Windows® is a registered trademark of Microsoft Corporation.
Index:
1 Document history ....................................................................................................4
2 Introduction .............................................................................................................4
3 Architecture.............................................................................................................4
4 Usage ......................................................................................................................4
4.1 Common problems:..........................................................................................5
4.1.1 Preserving module/entity names ...............................................................5
4.1.2 No output file generated ...........................................................................5
4.1.3 Class not found.........................................................................................5
4.2 VHDL Feature Special Note: ...........................................................................5
5 Planned Features......................................................................................................5
1 Document history
Version
ID
Date
Change
1.0
--
09/28/2004
Initial version
1.1
11/07/2004
VHDL support added
2 Introduction
HDLObf is intended to be a HDL Obfuscator and identifier name change utility.
Primarily designed for Verilog/SystemVerilog and initial support for VHDL. Feature to
obfuscate based on the scope of the identifier will be added in feature release. This will
allow modules/entity not supplied to the obfuscator or name change to be left alone.
System requirements JDK 1.4, ANTLR 2.7.4 (antlr.jar in classpath). Tested with
window/cygwin environment.
3 Architecture
The tool uses ANTLR tool to generate lexer/parser. ANTLR, ANother Tool for Language
Recognition, (formerly PCCTS) is a language tool that provides a framework for constructing
recognizers, compilers, and translators from grammatical descriptions containing Java, C#, or
C++ actions. ANTLR provides excellent support for tree construction, tree walking, and
translation.
The language specific lexer and parser are used in a general purpose obfuscator / Name
Change Tool
4 Usage
The usage options are
java HDLObf (GUI mode)
java NameChange <Language Name> <Map file> <input file name> <output file name>
java Obfuscator <Language Name> <Map file> <input file name> <output file name>
Operation: supported values NC (name change) or OB (obfuscate)
Map file: file name containing name mapping.
Language Name: support values ver, sv (system verilog), vhd and sc (systemc)
Obfuscator/NameChange Tool
HDL Language specific
Lexer/Parser
The map file is updated every time Obfuscator is used this will help running Obfuscator
in batch mode or for back tracking. By keeping the map file same and repeating the
command for different files will yield identifier map reuse in batch mode.
4.1 Common problems:
4.1.1 Preserving module/entity names
If there is a need to preserve a particular entity/module name during obfuscation please
make sure that you have that module name and its port entry in the map file, e.g.:
MyModule=MyModule
MyModuleport1= MyModuleport1
MyModuleport2= MyModuleport2
A preserve module and preserve non-declared module feature is planned for the next
release.
4.1.2 No output file generated
If there is a message “Could not create output file: <filename>” please check the
following:
1. Make sure the path exists and is not read-only.
2. Make sure the file dose not exist in the path. By default the program will not
overwrite and existing file.
For any other problems please send me a example if you can or give me as much detail as
you can.
4.1.3 Class not found
If you receive something like this:
Exception in thread "main" java.lang.NoClassDefFoundError: <classname>
Make sure you have the <HDLObf_HOME>/bin directory and antlar.jar in your
classpath. For confirmation use echo %CLASSPATH% on windows, if you are using
linux/unix you would know what to do.
4.2 VHDL Feature Special Note:
When using VHDL feature the IEEE or the STD library are not built in to the
lexer/parser. To avoid ieee, std functions and declarations to be obfuscated please append
the map file vhdl_map_ieee_std.map.dat located in <HDLObf_HOME>/src and/or
<HDLObf_HOME>/test.
5 Planned Features
(1) Scope based identifier name modification support.
a. To better obfuscate the code.
b. Ability to have modules that can be excluded form obfuscation
(automatically if not included in the list).
(2) Multiple files loading instead of one by one, like a –f option to have a file
with list of file names and output directory.
a. Improves performance, as the map needs to be loaded only once.
b. Required to implement feature (1).

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