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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How to fix CRC32 checksum in an xz-compressed folder without corrupting the data?

I need to fix the CRC32 checksum of an xz folder that is part firmware. I extracted the files from this folder, made the necessary modifications and recompiled using mksquashfs. How do I fix the ...
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Tenda router + Firmware-Mod-kit = Firmware header not supported

I have been working hard for over 1 week trying to get a modified firmware installed on a Tenda AC10 V1 router. It is the original firmware with some modifications to unlock extra features. The ...
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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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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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1 vote
1 answer
62 views

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”. ...
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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 ...
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Finding method for checksum calculation - CRC or XOR or other

I have RF connected devices for which I'm working on the protocol of data packets, as those are not supported by known software at the moment. Packets are pretty simple and consists only in 6 nibbles ...
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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, ...
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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 ...
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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 ...
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1 answer
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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 ...
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3 votes
1 answer
163 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 ...
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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 ...
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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 ...
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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 ...
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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....
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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-...
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3 votes
1 answer
265 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 ...
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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 = ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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2 votes
1 answer
138 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 ...
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-1 votes
1 answer
453 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 ...
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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 ...
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526 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 ...
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1 vote
1 answer
112 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 ...
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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 ...
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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 ...
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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. ...
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1 vote
1 answer
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Checksum field within IR protocol

I am trying to reverse engineer the IR protocol for my air conditioner (GREE - remote control YAP1FF) and with the data I found online and a lot of testing with a IR receiver there is only one field I ...
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1 vote
1 answer
273 views

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 ...
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2 votes
1 answer
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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. 55549d1748c2aa11d2044f ...
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Reverse engineer SharePoint hash algorithm

I'm trying to reverse engineer a hash algorithm used by SharePoint 2016 in MSSCrawlUrl database table. I would like to avoid discussions about the idea itself (which I agree goes against SharePoint ...
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Reverse engineer 8 bit check sequence for old unkown protocol

I am using an old piece of hardware which uses an RS485 serial interface. I'm trying to simulate slave node data but I don't have any documentation on the protocol and unfortunately the hardware is ...
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1 vote
1 answer
920 views

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 ...
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2 votes
1 answer
173 views

Identification of RF hash algorithm

I have an unbranded LED lamp with a remote control. I would like to reverse the protocol of the remote but unfortunately I can't create my own packages. The frequency of the remote transceiver is 2....
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1 vote
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Reverse engineering key fob checksum

I am trying to reverse engineer the key fob of my Ford Fiesta 2014 but I am stuck at finding the used checksum algorithm. I've successfully demodulates the key fob signal (using on-off keying + ...
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6 votes
1 answer
739 views

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, ...
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3 votes
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474 views

EEPROM data bytes verification

I'm investigating a tool. I have an section of an eeprom memory dump that this tool uses, shown in the figure below. By my inquiries, the two bytes highlighted in red are based on the bytes ...
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How to calculate checksum from known data? [closed]

I'm trying to create the algoritm to produce the actual checksum byte (D0) in a vehicle 11-bit CAN bus message, where all values are known by scanning the current bus (which I'm trying to replicate ...
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Reverse engineer CRC16

I have not had success with reveng on figuring out how to calculate these CRCs. I successfully figured out another similar CRC from the same author so I'm pretty sure that the first four bytes as ...
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1 vote
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How determine correct checksum algorithm for this NFC Data?

I maae a dump of a Mifare Classic, NXP, tag. I can read some information without a problem, but if I write data in a block, I need to terminate the block with a checksum (CRC?, one byte). I tried ...
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4 votes
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Backtracing where a register gets initialized

I am currently trying to bypass a CRC check, that exists inline on many places in an application to check if memory pages in the .text section have been modified. Short explanation of the crc32 ...
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3 votes
1 answer
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What Checksum/CRC algorithm in RF packet?

I am banging my head to figure out the checksum of a RF device, it seems to be a simple one but no luck so far... The first 3 bytes is the SyncWord then 9 bytes is the payload and the last byte ...
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