Jumper Boxer Ducato >> euro5 BSI CRC algorithm

[komiss]

Hi, enigmatic masters!
There is a need to make changes to the block with 2-bytes CRC.
This method is used to sign all data blocks, such as keys, vin and complectation.
I figured out how make second byte, but I ask for help with the first.
How to calculate it after data change?

examples:

30 38 32 35 30 32 33 31 34 33 36 4f 55 54 50 55
54 44 4a 49 54 20 15 07 29 00 00 00 4b 00 00 04
00 00 00 00 09 00 00 04 00 00 00 00 01 00 00 00
40 00 00 00 53 00 00 00 08 20 00 00 00 00 00 00
7c 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 16 00 00 00 00 00 00 00 00 00 00 00
00 04 06 00 12 00 00 00 00 00 00 02 28 c8 00 00
10 00 00 00 50 00 00 00 00 00 00 00 01 00 00 00
00 00 00 00 01 00 00 00 04 00 00 00 00 00 00 00
00 00 00 56 00 20 00 00 12 00 51 00 11 21 00 00
ff 00 23 00 00 20 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 a2 00 00 00 00 00 00 84 12 00 00
00 00 01 30 00 00 00 00 00 00 00 00 00 00 00 00
20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 01 00 00 1f 00 00
bb 00 00 00 20 00 00 00 00 02 ff 00 00 00 00 00
00 00
has CRC 0e and a3

00 68 00 6d 00 66 00 6c 01 0f 01 1a 01 24 01 25
01 17 01 13 01 24 01 2a 01 1f 01 15 02 f9 02 fe
00 a1 01 63 05 26 05 4a 05 26 05 4a 01 12 01 2b
00 ce 00 ce ff fe b0 03 01 0b 01 12 00 9a 02 59
00 00 00 00 00 00 00 00 00 00 00 00 00 00
has CRC 0c and 62

[jomberykaso]

Bad quality of picture, i can't identify anything there......you should upload your file here to play a little

[komiss]

Image updated.
So far, i discover that this byte never has high values, usually #01-#0f




!!!!!!!
Solved. It`s just a modulo65535