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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41 views

Reverse Engineering a Smart Card Password based on datastream

I'm trying to reverse engineer a smart card that I use. I've successfully used a usb logic analyzer to dump the datastream and am trying to reverse engineer the password (CSC1 / Card Secret Code) ...
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128 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 ...
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45 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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52 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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168 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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85 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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44 views

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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1answer
100 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 ...
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42 views

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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178 views

Reverse engineer CRC or checksum algorithm

I am trying to reverse engineer a checksum algorithm of car CAN bus data I tried to find with (CRC RevEng), but I can not find it how to calculate it I have captured communication can bus data. I ...
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77 views

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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151 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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1answer
144 views

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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57 views

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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78 views

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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1answer
268 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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1answer
155 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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185 views

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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311 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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326 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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1answer
141 views

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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179 views

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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338 views

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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2answers
269 views

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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1answer
225 views

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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1k views

CRC32 reverse engineer without knowing parameters, but knowing the input value

Dear members, I am trying to figure out the parameters of some hexadecimal CRC32 values I have. The values are: Value - input (before hashing) 55D3028A - J 73AF2D02 - O 6742BE71 - T I hope I can ...
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1answer
248 views

Reverse engineer CAN-Bus checksum

I am trying to figure out a checksum algorithm. D1 to D6 is data, D7 is a counter obviously and byte 8 must be a CRC, but I didnt have any idea on how to build it. Tried to check if it fits any ...
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140 views

Reverse engineer checksum in AC Sharp IR packet

i use microcontroller and received ir frame of air conditioner SHARP. This Ir frame have 13 byte data (in decimal number, not hex) like below: 85 90 243 8 131 140 66 0 176 1 32 7 133 85 90 243 8 142 ...
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302 views

Trouble finding the right Checksum algorithm

After reading a lot of posts here and their solutions, Punching lines in CRC calculators for several days now. I can't seem to find on which Checksum this code is based. Background This is a data ...
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2answers
226 views

Checksum in CAN message

I'm trying to fake a CAN message, but I'm not able to understand how the 8-bit checksum is calculated. The checksum follows a pattern along with a 4-bit rolling counter. As long as the data of the ...
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1answer
300 views

Find out the checksum/crc/whatever is used in this file

There is a game called The Hunter, call of the Wild, in which you can spend skill points in skills. Whenever you spend 1 skill point there is an statistics file in which 2 changes are done: the crc/...
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192 views

Need help for an unknown 7-bit checksum

i am struggling since a long time to determine the checksum of the following sequences. I have two examples. Ex1: Have the same checksum and one have a payload incrementation by 0x0A at the same ...
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1answer
2k views

Simple 8bit checksum

I'm trying to find out, how the checksumming in an RS485 communication works. The data is packetized and seems to be using 8bit checksums. One packet per line, the last byte that isn't 0x00 seems to ...
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89 views

Do I have sufficient information to determine a checksum algorithm?

What I would like to know is whether or not I have sufficient information to determine a particular checksum algorithm being used. In my case I have a very large stream of data with many frames of ...
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312 views

De-ciphering help needed

As a total noob in this territory, I am trying to decipher a serial protocol between two devices A and B. It looks like the frames that are sent from B to A are somehow protected with a CRC or ...
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1answer
642 views

Daikin A/C 4bit CRC/Checksum

I am reverse engineering IR protocol of Daikin A/C. AC sends the whole current state of remote on each key press. Data sent is 8 byte long, last 4 bits seem to be the some kind of error checking. ...
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1answer
631 views

Reverse engineering serial communication CRC algorithm

I'm working on reverse engineering the serial communication protocol of an obsolete electronic control system, but I'm having trouble figuring out the CRC algorithm and polynomial. I have reverse ...
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0answers
459 views

Reverse Engineering a 16-bit CRC algortihm

I have a set of data bytes and their CRC values available to me. I want to know the CRC algorithm used by it. CRC is 16 bit long. firstly I tried to find out using CRC RevEng but that is showing "no ...
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935 views

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 ...
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1answer
742 views

Reverse engineer checksum algorithm

I am trying to reverse-engineer the protocol used between my Air-conditioner and the wired control unit on my wall. (In order to have my home automation be able to monitor and control the A/C.) The ...
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2answers
5k views

how to bypass CRC checksum in firmware header

I have this Ubiquiti firmware and I successfully extract the firmware and rebuild it, I modify Squashfs filesystem and rebuild it using build-firmware.sh script from firmware-mod-kit, but the problem ...
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2answers
453 views

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 ...
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1answer
642 views

Figuring out the CRC part of a packet

Currently, I am trying to figure out the packet structure (for encryption) of an old MMO in order to create an emulator. Its official servers shut down 3 years ago and this version is over 11 years ...
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2answers
500 views

I really struggled to figure it out, now can anyone help me reverse engineer this checksum?

I have a device at work with no documentation about it's checksum calculation. I know that the last byte in each message is the checksum, and most of the messages to the device requires a correct ...
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133 views

figure out the CRC bytes [closed]

I am trying to write some code to figure out a CRC on the following byte sequence for an AI algorithm class project, and would like to seek some suggestions from this forum. For example, the ...
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1answer
186 views

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 ...
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0answers
269 views

Puzzling 16bit checksum/CRC reverse engineering problem

We're having a hard time figuring out how the checksum/CRC is calculated for this serial communication protocol we're required to reverse engineer. This is a communication protocol used back in the ...
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551 views

find CRC algorithm, having some input and output data pairs

I'm trying to discover the algorithm of a lost software, there is an equipment that requiest some data, and validates the data using the "KEY", if you change any parameter of the data then you need a ...
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1answer
257 views

Reversing checksum calculation of embedded communication

I need to find relations last byte with others. Tried these solutions, but it didn't work. My tries: * When I write all datas as binary, 1's count not equal but last byte same for some datas. * When ...