How can I remove strings containing type names from Delphi executables and globally disable RTTI for a project?

Question

UPDATE: Even though the above mentions: the question already has an answer, the solution in the linked question does not work in Delphi XE6

Just noticed that all executables generated with Delphi (including Release version) include the names of all types used by that executable and the names of the units they belong to. If you are not careful to remove the RTTI information then it also contains class methods, fields and property names.

What are these strings used for (especially in a Release version)?

Is there a way to prevent type and unit names from being written to the executable?

Steps to reproduce this:

1. Create a new Delphi project.

2. Define a class

   {$RTTI EXPLICIT METHODS([]) PROPERTIES([]) FIELDS([])}
   type TPerson = class
   private
     FName: string;
   public
     constructor Create(Name: string);
     destructor Destroy; override; 
   end;
   
   constructor TPerson.Create(Name: string);
   begin
     inherited Create;
     FName := Name;
   end;
   
   destructor TPerson.Destroy;
   begin
     inherited Destroy;
   end;
   

3. Create an object of that class so that the class is referenced/used.

   var person: TPerson;
   begin
     person := TPerson.Create('John Doe');
     person.Free;
   end;
   

4. Compile the project in Release mode.

5. Use a hex viewer and search for the name of the class (TPerson) in the executable.

How can one prevent the class name from being written to the executable?

also:

How can one remove RTTI at the project level so there would be no need to manually go through every included unit and add the {$RTTI EXPLICIT METHODS([]) PROPERTIES([]) FIELDS([])} clause?

I tried adding $RTTI EXPLICIT METHODS([]) PROPERTIES([]) FIELDS([])} at the top of the .dpr file but this doesn't work in Delphi XE6.

Answer 1

Pythia is a program that can obfuscate binaries created with Delphi or C++ Builder.

However, remember that a competent reverse engineer will only be slightly slowed down by this obfuscation, so I would only use it to prevent cursory tampering/inspection.

Download compiled v1.1 program here: http://www.the-interweb.com/serendipity/index.php?/archives/86-Pythia-1.1.html

Browse the source code here: https://github.com/sporst/Pythia

BEFORE:

AFTER:

Answer 2

The class name is stored in the executable because it is needed to implement TObject.ClassName.

There is no simple way, without resorting to gross hacks, to stop this happening. You could I suppose, have a post-build step that modified the executable file to overwrite the name in the executable. This would obviously break any code that relied upon the ClassName method.

Another option is obfuscation. I'm honestly not sure how much help it would be to a malicious hacker to be able to know the name of all your program's classes.

---

Your latest edit adds a new question:

How can one remove RTTI at the project level so there would be no need to manually go through every included unit and add the {$RTTI EXPLICIT METHODS([]) PROPERTIES([]) FIELDS([])} clause?

Add this to the very top of your .dpr file, immediately after the program statement:

{$RTTI EXPLICIT METHODS([]) PROPERTIES([]) FIELDS([])}

Although apparently, the ability to do this globally in the .dpr file was unintentional. And Delphi XE6 "fixes" this behaviour: http://qc.embarcadero.com/wc/qcmain.aspx?d=79943

So, if you happen to be using XE6, there appears to be no global project wide way to disable RTTI.