xorstr's Introduction

xorstr

A heavily vectorized c++17 compile time string encryption.

usage

auto xs = xorstr("Adasdads"); // xorstr(L"Adasdads") supported too
xs.crypt(); // does a pass of xor encryption
xs.get(); // returns pointer to data
xs.crypt_get(); // same as calling crypt() and then get()
xs.size(); // returns string size

noteworthy things

All keys are 64bit and generated during compile time.
Data blocks go in increments of 16 bytes so some space may be wasted.
The code has been crafted so that all the data would be embedded directly into code and not stored on .rdata and such.
The entirety of string encryption and decryption will be inlined.

supported compilers and platforms

Tested to be working on clang 5.0+, gcc 7.1+ and MSVC v141. If your CPU does not support AVX define JM_XORSTR_DISABLE_AVX_INTRINSICS to only use SSE.

example assembly output

Input code

int main() {
    // or alternatively xorstr_(...) which includes crypt_get call
    std::puts(xorstr("an extra long hello_world").crypt_get());
}

Output of gcc (trunk)

main:
  movabs rax, -4762152789334367252
  push rbp
  mov rbp, rsp
  and rsp, -32
  sub rsp, 64
  mov QWORD PTR [rsp], rax
  mov rdi, rsp
  movabs rax, -6534519754492314190
  mov QWORD PTR [rsp+8], rax
  movabs rax, -2862143164529545214
  mov QWORD PTR [rsp+16], rax
  movabs rax, -4140208776682645948
  mov QWORD PTR [rsp+24], rax
  vmovdqa ymm1, YMMWORD PTR [rsp]
  movabs rax, -2550414817236710003
  mov QWORD PTR [rsp+32], rax
  movabs rax, -4595755740016602734
  mov QWORD PTR [rsp+40], rax
  movabs rax, -5461194525092864914
  mov QWORD PTR [rsp+48], rax
  movabs rax, -4140208776682645984
  mov QWORD PTR [rsp+56], rax
  vpxor ymm0, ymm1, YMMWORD PTR [rsp+32]
  vmovdqa YMMWORD PTR [rsp], ymm0
  vzeroupper
  call puts
  xor eax, eax
  leave
  ret

Recommend Projects