Difference between revisions of "Sims 3:0x073FAA07"

Revision as of 06:38, 9 June 2009

Sims 3:Main Page -> Sims 3:PackedFileTypes

Signed assemblies, encrypted .NET assemblies. They function as the game scripts.

These are the scripts that run when a Sim interacts with an object, or another Sim, or just performs its own inner metabolic processes.

Currently no way is known to get the game to accept piecemeal overrides, so global hacks for a particular assembly as of 6 / 6 / 2009 are having to replace the entire set - meaning that you can only have global hacks for a particular assembly from one creator at a time.

It is probably possible to create new scripts for new custom objects, however. Technical details coming later.

Data format

BYTE            unknown1 ;; must be 1
DWORD           unknown2 ;; must be 0x2BC4F79F
BYTE[64]        checksum
WORD            count
QWORD[count]    decryption table
BYTE[count*512] encrypted data

(I think the checksum and encryption method are MD5Cng -- PLJ.)

Decryption method

Initialise the decryption seed by scanning the decryption table:

foreach(QWORD q in decryption table) decryption seed += q

Truncate (mask off) the decryption seed to the length of decryption table:

decryption seed = decryption seed & (decryption table Length - 1)

Now process each QWORD in the decryption table. Where an entry has bit 0 set, write 512 zero bytes to the output, otherwise, read 512 bytes into a buffer from the encrypted data and process as follows:

foreach(byte b in buffer)
{
  byte value = b;
  b ^= decryption table[decryption seed];
  decryption seed = (decryption seed + value) % (decryption table Length);
}

Then write out the decrypted buffer.

Encryption Method

To encrypt, reverse the process for Decryption. There is no need to create a valid checksum and the decryption table table can be left full of zeros (which saves identifying empty 512 byte chunks).

Data Content

The decrypted content is a Common Language Runtime signed assembly.

How the game uses Assemblies

TBC

Sims 3:Main Page -> Sims 3:PackedFileTypes