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 ...
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318 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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365 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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Reverse Engineering a 8 bit CRC checksum

I am trying to create a communication interface using C Language to an Air conditioning system, after analyzing the data packets I have identified that the data packet is consist of an 8 bit CRC (I am ...
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76 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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554 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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271 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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559 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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55 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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57 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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47 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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175 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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245 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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204 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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431 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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160 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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227 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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36 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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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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49 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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51 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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68 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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82 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 ...