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 a CRC-16

I am looking for help in reverse engineering what I believe to be a CRC-16. I have tried all of the known polynomials as well as bit and byte ordering with no success. I am able to determine that ...
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finding unknown CRC 32 bit algorithm used in a firmware file

I want to modify a firmware image for a WiFi router. The image file consist of an UBI image, 0x04100000 bytes in size. Additonally, 20 bytes of unknown metadata have been appended to the UBI image ...
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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 ...
Peter Fischer's user avatar
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Figuring a CRC to edit a PS1 save file

So I've set myself the goal of editing Crash Bash saves for the PS1. I'm using RetroArch + PCSX, so I'm editing memory card .srm files binary contents directly. Uploaded a zip with some save games, in ...
Xavier Arias Botargues's user avatar
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Makita XGT battery/charger protocol checksum

I am reverse engineering the communication protocol used by Makita XGT (40V) batteries. I have successfully captured a number of messages and have some hints at their basic structure, but they appear ...
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Finding CRC for a pocket of data

I'm trying to find the method and polynomial that used in a packet of data like that: 00 00 41 xx xx yy yy ............................ ff The first bytes (00 00 41) is a magic number that is used at ...
Kamil B's user avatar
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Derive logic for 2 "check bytes" for a USB fingerprint reader

I have been working on reverse engineering and building a Linux driver for a fingerprint reader and have most of it sorted out, but one thing which continues to elude me is that there seems to be 2 ...
joshuagrisham's user avatar
2 votes
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Bresser Water Leakage sensor checksum algorithm

I am trying to decode the Bresser Water Leakage sensor, the current state of work can be found in https://github.com/matthias-bs/rtl_433/blob/master/src/devices/bresser_leakage.c I have also created ...
Matthias's user avatar
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230 views

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 ...
Andy's user avatar
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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 undescribed....
David Given's user avatar
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Reverse Engineer 16 Bit error checking byte calculation

Hello =) I am attempting to reverse engineer a communications protocol to some obsolete equipment. Communication happens on an RS485 line. I have captured several exchanges and seem to have figured ...
Pau Coma Ramirez's user avatar
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determine if 2 byte checksum is CRC-16 based

I have pairs of data / messages with what I believe to be CRC-16 I know for a fact the bit order of each individual byte is reversed (at least in C# on x86 platform, I have to flip the binary around) ...
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can sha1 hash of file converted to sha2 hash?

I have a phone database /data/user/0/com.miui.gallery/databases/gallery.db containing information such as exif data and file name. there is a column sha1 containing value ...
alecxs's user avatar
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Please figure out how this Checksum was derived

I have hexadecimal data from first 5 blocks of T5557 125KHz RFID card. The 5th block appear to be some kind of checksum which I like to know how it is derived. Below are 11 different samples of the ...
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What Checksum Algorithm used

I have blocks 1 to 4 of an RFID card with 4-byte Hex data each. Block 5 contains some sort of 4-byte Hex data checksum which I would like to know how it was derived. Please see the 3 sample data below:...
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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 ...
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Reverse engineering 18 Bytes protocol

I'm not really used to do algorithm reverse engineering, so I need some help It's a SPI communication between a STM and a wireless chip, hopefully the data were correctly acquired by the logic ...
bigboss59400's user avatar
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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 &...
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Firmware-mod-kit failed with CRC update failed

hello I'm trying to modify firmware to enable telnet support when i tried to build firmware without any modification it give me these errors Firmware Mod Kit (build) 0.99, (c)2011-2013 Craig ...
isso's user avatar
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Reverse engineer CRC Canbus

I am trying to figure out what I believe is a CRC8 value on some 8 byte canbus messages. I have tried "RevEng" without luck. But maybe some of you are able to figure it out. Some messages in ...
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It does not appear to be a standard CRC. Can I know this formula in reverse?

Interpreting binary protocols for older equipment. I interpreted most of the contents of the protocol, but the last error detection part seems to be in crc16 form, but it does not seem to be standard. ...
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2-byte checksum

I cannot figure out what checksum is used for the following communication. As I understand, 450D is the “stop” part. It doesn't change no matter what. And the two bytes before 450D are the “checksum”. ...
kostinalex's user avatar
2 votes
1 answer
355 views

Reverse-engineering a weird 32-bit possibly not CRC checksum

I am trying to decode Arad/Master Meter utility water meter RF transmission. So far, I had success with reading the meter serial number and counter reading. The transmission looks like that: ...
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Is there a software that can reverse calculate checksums by brute force?

For reverse calculation of CRC checksums, there is a pretty nice tool – CRC reveng. I was looking for, and have not found, a similar tool that can do the same for non CRC checksums. For example, using ...
dieter reichl's user avatar
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What is this CRC32 algorithm (written in C), and how can it be written in Java or Python?

I've been trying to convert this CRC32 algorithm to Java or Python, but I haven't been successful, I believe it's because I'm not familiar enough with c. Note that I believe DAT_804818d0 is the seed, ...
Gamebuster19901's user avatar
1 vote
1 answer
87 views

Finding the hash algorithm for these payload-crc pairs

I have a remote for a LED panel which sends following 4 bytes data and last byte some sort of CRC/counter byte. I already know that the first 2 bytes are remote-id, the third byte is panel-id and the ...
LichtiMC's user avatar
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1 answer
264 views

Stuck in finding the algorithm of a save game file CRC/checksum

A sample message-CRC pair looks like this: 00000005 00000000 12121212 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 2F8376FE ...
Andreu Navarro's user avatar
3 votes
1 answer
373 views

Reverse engineering Roland TR-8S kit file format .t8k

I'm trying to figure out the file format that the Roland TR-8S drum machine uses for importing/exporting drum kits. My goal is to replace the sample (PCM) data within a kit. It's a proprietary binary ...
Michael Ganß's user avatar
4 votes
1 answer
408 views

Reverse engineering 16-bit checksum algorithm for 433Mhz RF remote control

I'm stuck trying to figure out how to calculate the two last checksum bytes (16-bits) of these packets. The remaining data fields are understood, and it is just the two last bytes that I am current ...
KevinD's user avatar
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Trying to find a checksum (possible CRC?) algorithm for CAN messages on a Porsche

I have the following problem. Besides CAN itself having a full checksum and stuff in the protocol, I have data sets where the first byte of the CAN message is some checksum generated in some unknown ...
Stefan's user avatar
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Is this a checksum/CRC response or cryptography?! Thanks

I've been pointed here from the Cryptography Stack Exchange so hopefully you can help me here! Long version of the story at the end....the short version is... I want to identify this CRC/cipher/crypto ...
joehodgy's user avatar
2 votes
1 answer
894 views

Checksum in CANbus Message

I'm trying to work out the calculation method for a checksum in a CAN message but I'm having some difficulties. I am unsure if there are actually 4 separate checksums, or one big one at the end of ...
RNtech's user avatar
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how to calculate a byte value

We are reversing the method of creating a byte array packet. These values are obtained by serialport monitor from mediatek metamode usb port.The values of both packets are changed by changing the imei....
ILYA20's user avatar
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2 votes
1 answer
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reverse a RF rolling code

I have the following codes from a rolling code RF garage fob I want to duplicate. There is a duplicator remote that able to get one code and learn the sequrence from it: https://www.ebay.com/itm/V2-...
user35420's user avatar
3 votes
1 answer
592 views

Decoding algorithm with checksum

I'm a newbie, so I'm asking for your help. I have to decode dumped data from an appliance because I wanted to try understand the data. The data are in this format and some information are known: 7E 00 ...
Daniel Davis's user avatar
1 vote
0 answers
223 views

Delphi mt38 CRC (Tricore 1766 Arch)

I want to calculate CRC32 for Delphi mt38 and found the below assembly algorithm and converted it to C. It seems that this algorithm is defined for n = 256 or 1024. I want to calculate CRC32 for n = ...
bahar's user avatar
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1 vote
1 answer
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CAN checksum algorithm

I am trying to caclulate a checksum algorithm. D0 is CRC, D1 to D2 is data. Maybe someone can help me with algorithm for checksum calculation? D0 D1 D2 D3 68 00 01 00 74 00 03 00 DD 01 01 ...
Pablo's user avatar
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2 votes
0 answers
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CRC16 Reverse in C166 Arch

Before that I asked about piece of code that used in this algorithm (here). Now I have a bit problem with the rest of algorithm. So I have to describe this with detail. Sorry if i vast your time for ...
Unicornux's user avatar
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2 answers
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What checksum algorithm is this?

I'm trying to control an air conditioning unit. The app and the unit communicate using the Broadlink protocol. I can decode the settings it's sending and replay them. The payload is 32 bytes but only ...
Enosh's user avatar
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2 votes
1 answer
274 views

crc - reverse engineering GAL16V8 checksum method

While working with the GAL16V8 (an old programmable logic device), I found out that the Programmers Electronic Signature (PES) of each GAL has a checksum byte I've read the PES of some GALs but was ...
dwery's user avatar
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2 votes
0 answers
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Which value is used for verifiying Zip password?

I am studying the way that can be used to check if a given password for an encrypted zip file is correct or not. I see this link: How does a zip file detect a correct password? In the answer of this ...
alancc's user avatar
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3 votes
2 answers
382 views

Reverse engineering the IBM BSC (Bisync) protocol

I am trying to connect to an old piece of communication controller which use the IBM BSC synchronous protocol but I have problems to get the CRC right. Background The protocol itself is described ...
Mattis Lind's user avatar
2 votes
1 answer
211 views

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 ...
Malvineous's user avatar
-1 votes
1 answer
795 views

CAN Bus checksum

Maybe someone can help me with algorithm for checksum calculation. CRC 8 does not fit. Left byte is CRC. B9 30 13 00 00 20 00 00 36 31 13 00 00 20 00 00 BA 32 13 00 00 20 00 00 35 33 13 00 00 20 00 ...
Tarantula's user avatar
1 vote
0 answers
84 views

Bin patching Arm7tdmi CRC32?

Ok so I am total noob here. I wanted to play with the bin from an instrument cluster I work on a lot. I was able to pull the bin off the MCU with a J-link. If I erase the chip and flash it with a bin ...
Matt's user avatar
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3 votes
2 answers
990 views

Reverse engineering a checksum algorithm

I am attempting to implement an editor for a discontinued hardware drum synthesizer which uses undocumented system exclusive MIDI messages for communication. I've figured out the patch format, but I ...
user2390115's user avatar
1 vote
1 answer
135 views

Finding the CRC / Checksum in a control unit message

I have a list of messages from a control unit that i'm trying to replicate. I have the body of the message correct, however, i can't seem to work out what CRC or checksum is being utilised. 00 FE 0F ...
RNtech's user avatar
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Checksum of an old serial devices

I've got an old devices which communicate through serial port. There's main device which send simple commands and then asked device responds. I've got almost all sorted out. The only thing left is the ...
h2pc's user avatar
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0 votes
1 answer
786 views

Determine checksum / CRC algorithm

I am doing reverse engineering on some network protocol. It is client to server communication and I am pretty stuck with identifying checksum (or CRC) algorithm used in packet structure. I tried ...
Tomas's user avatar
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1 vote
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CRC Checksum? (Used in can open system)

We want to put our own messages on a can-open system. (So we can program our own functions to the system). We can put our message on the system, but when we do this, the safety relay stops the system. ...
Rikketick's user avatar