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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58 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 ...
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1answer
49 views

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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1answer
146 views

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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1answer
83 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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70 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 = ...
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1answer
71 views

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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67 views

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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2answers
138 views

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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67 views

Reverse Engineering an 8 bit CRC

I am doing reverse engineering on some IR packets, I'm trying to figure out a CRC for some data but with no success, i tried the checksums (sum, xor...), CRC calculator crccalc.com, Reveng but with no ...
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1answer
91 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 ...
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78 views

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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50 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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2answers
166 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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1answer
72 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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1answer
179 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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59 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 ...
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2answers
370 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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1answer
99 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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54 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
145 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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0answers
48 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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1answer
102 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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198 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
252 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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76 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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0answers
84 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
500 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
169 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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271 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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1answer
494 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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381 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
226 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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225 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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490 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
383 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
261 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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1answer
2k 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
462 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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163 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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325 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
260 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
322 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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245 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
3k 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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1answer
100 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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1answer
319 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
715 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
709 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
632 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 "...
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1k 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 ...