Reverse Engineering Stack Exchange
Reverse Engineering Stack Exchange

Questions tagged [crc]

Cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data.

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Reverse Engineering 2 byte checksum on RFID card

I am currently researching my studentcard. Money is stored on this card. But the vending machine also checks a checksum on the card. I already did a lot of effort to find it but didn't succeed. The information: Studentcard layout: Some transaction…
6kgstront
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Backblaze 16-bit checksum ("bzsanity")

I use Backblaze to back up my computer. You restore files from your backups by selecting files to restore, which are then packed into large zip files. Of course, it's fairly rare to be able to download a 500GB zip file without a connection…
Reid Rankin
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Reverse-engineering a weird 24-bit possibly not CRC checksum

Yes, it's one of these! I have a 199mumble Brother integrated word processor, with a very weird non-PC floppy format. I've built a floppy controller and have successfully read the flux off the disk, decoded both kinds of GCR, and reassembled the…
David Given
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Reverse engineering of some checksum algorithm

I am trying to reverse some communication protocol between transmitter (controlled by PCF7952 chip) and receiver on 433 Mhz frequency I know how to prepare the "right" package which would be received and controller on the receiver's side 100% will…
Alexander Dimchenko
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Figuring out a (possibly 16-bit) CRC algorithm

So, I wanted repurpose some old boarding gate scanners and I'm trying to make use of their commands. Now, I have a dump from an actual boarding gate PC and I've noticed that the commands only work if I send them as they are on the dump. If I change…
Gavouli
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What is 'standard' CRC-16?

The Linux source code has a routine for calculating CRC-16s. It's described as 'standard CRC-16', but doesn't have a formal name. It seems to be using a polynomial of 8005 but is otherwise…
David Given
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Reverse engineering CRC8 algorithm

I am trying to reverse-engineer a protocol which includes a final byte that is (possibly) a CRC-8 with some unknown parameters. I have collected some data, however, the downside is the fixed length <------------------ data ------------------> CRC…
Afck
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Checksum Calculation

Can anyone manage to work out how the checksum is calculated in the following data? Have tried reverse engineering crc and xor and anything else I can think of. There is a definite pattern there, but I cant work it out. C8 00 02 DD 01 02 53 02 02 CC…
Lodge
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Reverse engineering CRC and rolling code

Using an SDR I read out the transmitted message of a key fob for my old car. The car is a 98 Mercury Grand Marquis. It's quite old so I dought it's very sophisticated.…
vini_i
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CRC8 reverse engineering

I am creating a CAN Bus on-bench testing solution which replicates the entire vehicle to test a single module. I have a number of messages that require a CRC byte in order to be valid. The messages are in little-endian byte order, and the CRC value…
JPToadstool
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Help reverse engineering a CRC

Evening all Been trying to reverse-engineer the CRC for this data, and no clue what CRC is being used. What we think is the first 6 bytes are the data, the 7th is a sequence number, and the 8th the actual CRC. So: Data: 277F0000FFFF…
Andy
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Behringer CRC8 algorithm

The Behringer DEQ2496 audio device can have commands sent to it via MIDI, however they require a valid CRC code in order for the device to accept them. I have thus far been unable to work out how the CRC code is calculated. The manual suggests it…
Malvineous
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Trying to figure out the CRC or checksum for a Fluke 233 wireless display multimeter

Downloaded and compiled CRC_reveng, but it's not finding any solutions. Maybe I'm over-thinking this? Not knowing too many other tricks that might be performed on the data or CRC before or after it's computed, I'm looking for guidance. I tried…
sencore
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Bypassing CRC check

I am trying to reverse a software which loads its own dll-file filled with protection stuff. I was able to successfuly locate the functions of interest. Then I patched the first function and test the software. It worked. Then I patched the second…
user12715
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CRC8 CAN message reverse engineering II

I have the same situation as in question CRC8 reverse engineering. But changing the final XOR value seems not to solve my problem and reveng does not help as well. I am copying the text from the original question here again: I am creating a CAN Bus…
Peter Fischer
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