deniskore / llvm Goto Github PK

Hi @Deniskore
Thanks for sharing the project!
I have couple of questions.

1. Whether I correctly understand that the '-obfuscate' parameter passed to the clang have to have the function name being obfuscated? In your example, clang is used as: clang -O2 file.cpp -mllvm -obfuscate="func1,func2"
   At the same time, your test app has only the 'main' function to be defined.
2. I tried to pass the original parameter -obfuscate="func1,func2" as well as the -obfuscate="main" parameter for the '-target aarch64-linux-android' but the decompiled output looks as regular decompiled code without obfuscation.
   Below is the decompiled output

int __cdecl main(int argc, const char **argv, const char **envp)
{
  unsigned int v3; // w19
  unsigned int v4; // w20
  const char *v5; // x0
  __int64 v6; // x1
  __int64 v7; // x2

  v3 = rand();
  v4 = rand();
  printf("a=%d b=%d\n", v3, v4);
  printf("g=%d\n", v4 ^ v3);
  if ( (int)v3 <= (int)(v4 ^ v3) )
    printf("12345");
  printf("123456");
  printf("%d %p %d\n", (v4 ^ v3) + v3, &STACK[0xC160], (v4 ^ v3) + v3);
  printf("%d %d\n", 0xBC61BDLL, 0x96B43FLL);
  if ( v3 == v4 )
  {
    v5 = "a==b %d %d\n";
    v6 = v3;
    v7 = v3;
  }
  else
  {
    v5 = "a!=b %d %d\n";
    v6 = v3;
    v7 = v4;
  }
  printf(v5, v6, v7);
  return 0;
}

It would be nice to get your comments.

hi, clang 14 unable to compile llvm/Transforms/Obfuscate/XorShift.h because __rdtsc ((x)intrin.h) doesn't exist on arm. I think fix is replacing __rdtsc() with __builtin_readcyclecounter()

How do you think whether it is possible to implement the obfuscator as a LLVM plugin?
It would be very flexible solution for using with different toolchains.
As an example, following project can be taken.
https://polarply.medium.com/build-your-first-llvm-obfuscator-80d16583392b
https://github.com/tsarpaul/llvm-string-obfuscator

The idea is clear and simple. First, we generate the bitcode then process the bitcode with our plugin and after that translate it to the native code.

clang -emit-llvm hello.c -c -o hello.bc
opt -load-pass-plugin=./build/StringObfuscator/libLLVMStringObfuscator.so -passes="string-obfuscator-pass" < hello.bc -o out.bc
llc out.bc -o out.s
clang -static out.s -o out