evo adj chk

[zvahq]

Does anyone know how checksum is calculated for adj after editing it? Is there other tools available other than hutools?

 

[superwofy]

Does anyone know how checksum is calculated for adj after editing it? Is there other tools available other than hutools?

It's a CRC32 stored between bytes 0 and 3 (inclusive).

This is the function that calculates it:

UINT32 crcCalc(UINT32 crc,UINT8 *data,UINT32 len)

{
  UINT32 crct;
  uint uVar1;
  int iVar2;
  UINT32 i;
  uint uVar3;
  UINT32 j;
  int iVar4;
  UINT32 crcTab [256];
 
  iVar2 = 0;
  do {
    iVar4 = 0;
    uVar1 = iVar2 << 0x18;
    do {
      if ((int)uVar1 < 0) {
        uVar1 = uVar1 * 2 ^ 0x4c11db7;
      }
      else {
        uVar1 = uVar1 * 2;
      }
      iVar4 = iVar4 + 1;
    } while (iVar4 != 8);
    crcTab[iVar2] = uVar1;
    iVar2 = iVar2 + 1;
  } while (iVar2 != 0x100);
  uVar1 = ~((uint)data[1] << 0x10 | (uint)*data << 0x18 | (uint)data[2] << 8 | (uint)data[3]);
  for (uVar3 = 0; uVar3 < len - 4; uVar3 = uVar3 + 1) {
    uVar1 = crcTab[uVar1 >> 0x18] ^ (uVar1 << 8 | (uint)data[uVar3 + 4]);
  }
  return ~uVar1;
}

0x4c11db7 POLY and reverse=true.
I don't have the time to figure out the exact offsets of the data it computes over.


There's a much simpler way tho. Modify your adjust file, put it on a flash drive and run:

sysetadjread  --check=/fs/usb0/adjust_edited.bin

Output:

sysetadjread: WARNING: check: stored CRC: 7B19ACE5, calculated CRC: 2D026109
FAILURE

Note that the sum is stored in Little Endian in the file.


-PS I did not test what happens if you try to push this file. But since the CS is obtained from the OS binary it's definitely correct.