Vida CEM swapping

Treur · Post by **Treur** » 11 Jul 2025, 03:47

Yes, that's CEM L

Dudde · Post by **Dudde** » 11 Jul 2025, 03:48

Treur wrote: 11 Jul 2025, 03:47 Yes, that's CEM L

And you got the key from flash? Also what serial number is the CEM?

Treur · Post by **Treur** » 11 Jul 2025, 06:45

Yes, key from flash, I don't remember serial, but it's a 835 mcu.
I have decrypted eprom by io-terminal for compare.
I see that using my code I decrypt the first 61 bytes correctly.

files.zip: (121.35 KiB) Downloaded 51 times

Dudde · Post by **Dudde** » 11 Jul 2025, 07:27

Treur wrote: 11 Jul 2025, 06:45 Yes, key from flash, I don't remember serial, but it's a 835 mcu.
I have decrypted eprom by io-terminal for compare.
I see that using my code I decrypt the first 61 bytes correctly.
files.zip

I can give you solution when i get home

Treur · Post by **Treur** » 11 Jul 2025, 07:49

Dudde wrote: 11 Jul 2025, 07:27
Treur wrote: 11 Jul 2025, 06:45 Yes, key from flash, I don't remember serial, but it's a 835 mcu.
I have decrypted eprom by io-terminal for compare.
I see that using my code I decrypt the first 61 bytes correctly.
files.zip
I can give you solution when i get home

Ok, thanks. I already decrypted 183 bytes
..................
..................
Decrypted all file.

Yariy · Post by **Yariy** » 13 Jul 2025, 10:40

Hi everybody. I wrote SBL for CEMB to read the full contents of the flash. While in test mode, CAN packets are transmitted in uncontrolled mode with 8 bytes of data. 512 KB is transmitted in 1.3 minutes. The period between CAN packets is 1.192 milliseconds. I receive all data packets on the table without errors. And now I have some questions. 1. Isn't the time between data packets 1.192 milliseconds short if you read the block remotely via the Internet? 2. Is it necessary to make the transfer of controlled request-response type instead of uncontrolled data transfer?

dikidera · Post by **dikidera** » 13 Jul 2025, 12:41

You can always dump it and send in chunks. Usually ping is high, its nowhere near 1ms unless done locally.

Yariy · Post by **Yariy** » 13 Jul 2025, 12:56

dikidera wrote: 13 Jul 2025, 12:41 You can always dump it and send in chunks. Usually ping is high, its nowhere near 1ms unless done locally.

Thank you. I will send the data in parts with checksum calculation. If the block checksum is incorrect, then send it again.

Treur · Post by **Treur** » 13 Jul 2025, 13:57

Yariy wrote: 13 Jul 2025, 10:40 Hi everybody. I wrote SBL for CEMB to read the full contents of the flash. While in test mode, CAN packets are transmitted in uncontrolled mode with 8 bytes of data. 512 KB is transmitted in 1.3 minutes. The period between CAN packets is 1.192 milliseconds. I receive all data packets on the table without errors. And now I have some questions. 1. Isn't the time between data packets 1.192 milliseconds short if you read the block remotely via the Internet? 2. Is it necessary to make the transfer of controlled request-response type instead of uncontrolled data transfer?

Оптимально читать блоками по минимально 16 сообщений за раз (обычно используется по 32) в режиме запрос-ответ. То есть послали запрос, в котором указали откуда читать, что читать и по сколько сообщений за раз выдавать, получили сообщения, получили завершающее сообщение (можно сунуть КС например) и запрашиваем следующую порцию. И так далее. Через интернет напрямую блоки не читают ибо там совершенно конские с точки зрения CAN задержки (~100ms >). Обычно читается локально софтом и по мере поступления, или всё сразу отгружается по сети получателю.

Кстати, если КС не правильная, блок не должен ни чего повторять сам, это задача софта.

WhizzMan · Post by **WhizzMan** » 14 Jul 2025, 00:40

Yariy wrote: 13 Jul 2025, 10:40 Hi everybody. I wrote SBL for CEMB to read the full contents of the flash. While in test mode, CAN packets are transmitted in uncontrolled mode with 8 bytes of data. 512 KB is transmitted in 1.3 minutes. The period between CAN packets is 1.192 milliseconds. I receive all data packets on the table without errors. And now I have some questions. 1. Isn't the time between data packets 1.192 milliseconds short if you read the block remotely via the Internet? 2. Is it necessary to make the transfer of controlled request-response type instead of uncontrolled data transfer?

Would you be willing to share your code so we can do our own dumps?