MP3Car.com - View Single Post - Renault "Tuner List" Head Unit/CD changer hacking

Putput · 02-11-2006, 10:54 AM

I think I've found the CRC. I developed a prog that can load a text file with the following format:

3Dh 38h 0Bh 47h 01h 01h 00h 00h 45h 00h 00h 00h 43h 00h
3Dh 39h 0Bh 47h 01h 01h 00h 00h 46h 00h 00h 00h 44h 00h
3Dh 3Ah 0Bh 47h 01h 01h 00h 00h 47h 00h 00h 00h 45h 00h

and so on. As you can see there are only 14 bytes, the last byte is removed from Vicne's logfile (lines MUST be 56 chars long!).
When you push the Calculate button it starts to calculate a CRC or actually a FCS for each frame and adds it to each line. When the frame starts with 3D it calculates the FCS perfectly, only when it starts with 3F it goes wrong. When I change the 3F to 3D the result is ok again, so maybe the 3F could be a glitch? Only problem is, when I zip it the file is 203kb in size and the maximum size for attached files is 200kb on this forum

I will try to send it in a PM to Vicne.

02-11-2006, 10:54 AM	#40
Putput Constant Bitrate Join Date: Sep 2005 Location: Belgium Posts: 177	CRC or FCS I think I've found the CRC. I developed a prog that can load a text file with the following format: 3Dh 38h 0Bh 47h 01h 01h 00h 00h 45h 00h 00h 00h 43h 00h 3Dh 39h 0Bh 47h 01h 01h 00h 00h 46h 00h 00h 00h 44h 00h 3Dh 3Ah 0Bh 47h 01h 01h 00h 00h 47h 00h 00h 00h 45h 00h and so on. As you can see there are only 14 bytes, the last byte is removed from Vicne's logfile (lines MUST be 56 chars long!). When you push the Calculate button it starts to calculate a CRC or actually a FCS for each frame and adds it to each line. When the frame starts with 3D it calculates the FCS perfectly, only when it starts with 3F it goes wrong. When I change the 3F to 3D the result is ok again, so maybe the 3F could be a glitch? Only problem is, when I zip it the file is 203kb in size and the maximum size for attached files is 200kb on this forum I will try to send it in a PM to Vicne.