Control Flow Obfuscation

Control flow obfuscation can obfuscate the direction of code control flow, making it difficult to analyze the actual execution flow of code.

Algorithm

Currently only the following control flow obfuscation algorithms are implemented:

• Control flow flattening algorithm. This converts all code basic blocks into case items of a switch state machine, controlling the next code segment to execute by specifying the next execution index.

Settings

ObfuzSettings.ControlFlowObfusSettings contains constant encryption related settings, detailed documentation can be found in Configuration.

Rule Files

By default, Obfuz encrypts all function calls, but also supports rule files to finely control the scope and effects of constant encryption. The ControlFlowObfusSettings.RuleFiles option can configure 0-N rule files. Rule file relative paths are from the project directory, valid rule file paths look like: Assets/XXX/YYY.xml.

Configuration example:

<?xml version="1.0" encoding="UTF-8"?>

<obfuz>

  <global obfuscationLevel="Basic">

  </global>
  
  <assembly name="Obfus2">
      <type name="*.TestNotObfusAnyMethods" obfuscationLevel="None"/>
      <type name="*.TestObfusAll" obfuscationLevel="Advanced"/>
      <type name="*.TestObfusSomeMethods" >
          <method name="Foo" obfuscationLevel="MostAdvanced"/>
      </type>
  </assembly>
</obfuz>

• Top-level tag must be obfuz
• Second-level tags can be global and assembly

global

Global defines global default encryption parameters.

Attribute	Nullable	Default	Description
obfuscationLevel	Yes	None	Obfuscation level, can take values None, Basic, Advanced, MostAdvanced

assembly

Attribute	Nullable	Default	Description
name	No		Assembly name, must be in the obfuscated assembly list
Others	Yes	Inherit same-named options from global	All options in global can be used, if not defined, inherit the value of same-named option in global

Assembly's child elements can only be type.

type

Attribute	Nullable	Default	Description
name	No		Type name wildcard string, if empty means match all types
Others	Yes	Inherit same-named options from assembly	All options in global can be used, if not defined, inherit the value of same-named option in assembly

Since function calls can only appear in function code, type's child elements can only be method.

method

Attribute	Nullable	Default	Description
name	No		Type name wildcard string, if empty means match all types
Others	Yes	Inherit same-named options from assembly	All options in global can be used, if not defined, inherit the value of same-named option in assembly