hitcon-2017-quals-secret-fs.c

int __cdecl __noreturn main(int argc, const char **argv, const char **envp)
{
  unsigned __int64 v3; // rax
  size_t len_input; // rax
  int v5; // [rsp+Ch] [rbp-64h]
  FILE *stream; // [rsp+10h] [rbp-60h]
  void *file_content; // [rsp+18h] [rbp-58h]
  char n; // [rsp+20h] [rbp-50h]
  char result; // [rsp+30h] [rbp-40h]
  char e; // [rsp+40h] [rbp-30h]
  char m; // [rsp+50h] [rbp-20h]
  unsigned __int64 v12; // [rsp+68h] [rbp-8h]

  v12 = __readfsqword(0x28u);
  initial();
  __gmpz_init((__int64)&n);
  __gmpz_init((__int64)&result);
  __gmpz_init((__int64)&e);
  __gmpz_init((__int64)&m);
  puts("File list:");
  system("ls");
  while ( 1 )
  {
    printf("Input filename(txt) : ", argv);
    argv = (const char **)filename;
    v5 = read(0, filename, 0xFuLL);
    if ( filename[v5 - 1] == 10 )
      filename[v5 - 1] = 0;
    if ( filename[0] )
    {
      if ( (unsigned int)check(filename) )
      {
        v3 = strlen(filename) + 0x602120;
        *(_DWORD *)v3 = 'txt.';
        *(_BYTE *)(v3 + 4) = 0;
        argv = (const char **)"rb";
        stream = fopen(filename, "rb");
        if ( stream )
        {
          file_content = malloc(80uLL);
          if ( !file_content )
          {
            puts("something wrong!!");
            exit(0);
          }
          memset(file_content, 0, 80uLL);
          fread(file_content, 80uLL, 1uLL, stream);
          __gmpz_set_str(&n, &rsa_n, 10LL);
          __gmpz_set_ui(&e, rsa_e);
          len_input = strlen((const char *)file_content);
          __gmpz_import(&m, len_input, 1LL, 1LL, 0LL, 0LL);// m = file_content
          __gmpz_powm(&result, &m, &e, &n);     // m ** e % n
          argv = (const char **)&result;
          __gmp_printf("Result: %Zd\n", &result);
          free(file_content);
          fclose(stream);
        }
        else
        {
          puts("error");
        }
      }
      else
      {
        puts("error");
      }
    }
  }
}
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