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Author Topic: FRF and SGO - Differences?  (Read 108752 times)
Sagishm
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« Reply #90 on: October 11, 2020, 03:33:06 PM »

Hi All,
i try to understand what is the way to convert file with `ENCRYPT-COMPRESS-METHOD  = 11` but is not BCB like in med17.
i had success to convert files from med17 but not from dsg box.

someone can give me more information?

example to file is attached.
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gremlin
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« Reply #91 on: October 12, 2020, 07:54:36 AM »

someone can give me more information?
example to file is attached.
This TCU use 256 bytes encryption table and LZZ-compression.
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Sagishm
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« Reply #92 on: October 13, 2020, 03:12:02 AM »

This TCU use 256 bytes encryption table and LZZ-compression.

256 bytes encryption = AES256?
Where can i find the key and iv?

thanks
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gremlin
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« Reply #93 on: October 13, 2020, 10:12:24 AM »

256 bytes encryption = AES256?

Nо, it's not AES.
In-house manufacturer's algorithm.
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Sagishm
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« Reply #94 on: October 13, 2020, 11:21:54 AM »

Nо, it's not AES.
In-house manufacturer's algorithm.
So basically to find the algorithm i need to dissembling bin file and that’s will be in the bootloader?
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vagabond45
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« Reply #95 on: November 25, 2020, 04:08:42 PM »

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« Last Edit: December 12, 2022, 12:59:45 PM by vagabond45 » Logged
IamwhoIam
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« Reply #96 on: November 27, 2020, 06:01:40 AM »

Hi. Trying to find some info on the compression algo used on the file attached. med17.85 ecu..

You can dm me as well if this is too off topic to the rest of the convo.

It wouldn't hurt if you provided some more info about what the file comes out of, just sayin'
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I have no logs because I have a boost gauge (makes things easier)
vagabond45
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« Reply #97 on: December 16, 2020, 12:21:48 AM »

It wouldn't hurt if you provided some more info about what the file comes out of, just sayin'

My fault. Updated the initial post. The file is an eeprom read i took from ktag.
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navatar_
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« Reply #98 on: December 26, 2020, 09:50:17 PM »

This TCU use 256 bytes encryption table and LZZ-compression.

Can anyone shed some light on the 'LZZ' compression algo? At first I assumed it was synonymous with LZSS but unless I am missing something obvious, the compressed bitstream looks quite different to that of the LZSS used in other ECUs like Sim18.
« Last Edit: December 26, 2020, 10:16:43 PM by navatar_ » Logged
Wommesz
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« Reply #99 on: December 27, 2020, 10:51:36 AM »

Quote
Can anyone shed some light on the 'LZZ' compression algo? At first I assumed it was synonymous with LZSS but unless I am missing something obvious, the compressed bitstream looks quite different to that of the LZSS used in other ECUs like Sim18.

This is far from an answer, but maybe it's helpfull to know:

We might be looking at something similar, even though this is from a Simos 10 ECU:
http://nefariousmotorsports.com/forum/index.php?topic=18832.msg142207#msg142207
I haven't gotten any further since that post. Maybe with a decrypted boot section and a dissasembler it's possible to locate the decryption routine.
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moodz
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« Reply #100 on: January 09, 2021, 11:14:39 AM »

not sure if this helps here

Search for Patent Application 20150333766

A method for run time zero byte compression of data on a communication bus of a vehicle includes determining a number of zero bytes provided in a data frame. When there are enough zero bytes, an encoding byte is generated that maps the locations of the zero bytes in the data frame. A data length code related to the number of non-zero data bytes and the encoding byte is provided in a device header. The data length code has a value less than an uncompressed data frame. The compressed data frame is transmitted with the encoding byte and the uncompressed non-zero data bytes. To decompress the compressed data frame, the encoding byte maps the locations of the zero bytes for a data frame. The non-zero data bytes are then provided at the proper locations to recreate the data frame.
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---------------------------------------
Wayne Modz (ToxicTuning)
nyet
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« Reply #101 on: January 10, 2021, 02:03:32 AM »

Jesus I hate patent authors.

"the encoding byte maps the locations of the zero bytes for a data frame" is mentioned twice.

But zero mention of how the locations are encoded in the encoding byte, nor does it mention if the length of the consecutive zeros are encoded, though it is obvious that the encoding would be pointless without it.

They really are scum. Describe a method just enough to make the description utterly useless so the patent cannot be used to reproduce the technology, which (ostensibly) is the purpose of a public patent system (not to enrich the authors, even though that is the common wisdom of the purpose of a patent system).
« Last Edit: January 10, 2021, 02:05:23 AM by nyet » Logged

ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
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« Reply #102 on: March 09, 2021, 01:59:18 PM »

Next levels of compress/crypt algo from Bosch -> A1, AA and 2A use LZRB and AES technique.

Gremlin what exactly is LZRB? I know of LZRW & LZJB but I can't find any reference to an LZRB compression algo outside of this thread?
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gremlin
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« Reply #103 on: March 09, 2021, 05:36:01 PM »

I can't find any reference to an LZRB compression algo outside of this thread?

LZRB means manufacturer specific (Robert Bosch) modification of LZ compression technique.
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navatar_
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« Reply #104 on: March 09, 2021, 08:59:21 PM »

LZRB means manufacturer specific (Robert Bosch) modification of LZ compression technique.


I see. Thanks gremlin.
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