Thread: Super Dancer Online-Xtreme | Season 3 SAI Decrypt

Victim: here
Format: SAI

So we have 2 files:

1) Datas.sai - FileTable where contained info about Offset's, Size's, FileNames .ect. (Encrypted)
2) Datas.sac - Main archive where contained game resource's. (Not Encrypted) - You can use any ripper to get files.

FileTable divided into 2 blocks.

1st block - Index where contained info (Offset's , Size's, CRC and other)
2nd block - FileNames strings.

Structure :

Full Header Size = 16 Bytes

Code:

4 Bytes - SDO\x00
4 Bytes - TotalFiles inside main archive
4 Bytes - 2nd Block Size
4 Bytes - Nulls

What next. We need decrypt 1st block. How :

Offset: 0x10
Size: 2971750 (FileSize) - 16 (Header) - 1911206 (2nd Block Size) = 1060528

Now decrypt 2nd block.

Offset: 2971750 (FileSize) - 16 (Header) - 1911206 (2nd Block Size) = 1060528
Size: 2nd Block Size

Algo is very simple

PHP Code:

int __cdecl SAI_Decrypt(unsigned int szKey, int szBuffer, unsigned int szBlockSize)
{
  int result;
  int i;

  if ( szKey )
  {
    result = szBuffer;
    for ( i = szBuffer; i < szBlockSize; ++i )
    {
      szKey *= 15625;
      *(BYTE *)i -= szKey >> 16;
      result = i + 1;
    }
  }
  return result;
} 


szKey -> 0x7C53F961u

Example Use:

PHP Code:

SAI_Decrypt(0x7C53F961,(int)buffer, (int)buffer + size); 


Now you can use FileTable for extract game resource's with normal filenames

Test Project Attached (Original FileTable + Decrypted included).

So unpacker here