BUUCTF RE [WUSTCTF2020]level1

[WUSTCTF2020]level1

1.无壳

2.IDA

int __cdecl main(int argc, const char **argv, const char **envp)
{
  int i; // [rsp+4h] [rbp-2Ch]
  FILE *stream; // [rsp+8h] [rbp-28h]
  char ptr[24]; // [rsp+10h] [rbp-20h] BYREF
  unsigned __int64 v7; // [rsp+28h] [rbp-8h]

  v7 = __readfsqword(0x28u);
  stream = fopen("flag", "r");
  fread(ptr, 1uLL, 0x14uLL, stream);
  fclose(stream);
  for ( i = 1; i <= 19; ++i )
  {
    if ( (i & 1) != 0 )
      printf("%ld\n", (unsigned int)(ptr[i] << i));
    else
      printf("%ld\n", (unsigned int)(i * ptr[i]));
  }
  return 0;
}

output.txt内容

198
232
816
200
1536
300
6144
984
51200
570
92160
1200
565248
756
1474560
800
6291456
1782
65536000

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