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Questions tagged [checksum]

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2 votes
2 answers
122 views

Reverse Engineer an ultrasonic cartridge communication with the station to bypass remaining uses

I Have an ultrasonic machine that has a cartridge with a set amount of uses. When that value gets to 0, the cartridge has to be disposed, and a new one bought. The thing is that with some maintenance ...
fpp's user avatar
  • 41
0 votes
1 answer
212 views

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
0 votes
1 answer
183 views

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 ...
Malvineous's user avatar
2 votes
1 answer
126 views

Mr Cool Remote Control Checksum Algorithm

For fun I've decided to reverse engineer the Mr Cool IR Remote, and build my own version of it. I've been able to capture the IR sequence for a lot of different button presses. It appears to use a ...
ToddD's user avatar
  • 23
1 vote
1 answer
49 views

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
1 answer
50 views

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
3 votes
1 answer
236 views

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
2 votes
1 answer
269 views

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) ...
HANGOBA's user avatar
  • 29
2 votes
1 answer
294 views

Calculate a 3 byte checksum in configuration file

I have 3 different encrypted configuration files. The first line of the files are always the same (M1.28...). Following lines are as follow for exmaple: 1N].1f01f ("1N]" is the checksum for ...
Hans Biedemann's user avatar
2 votes
1 answer
1k views

J1939 message payload checksum

I am attempting to reverse engineer some proprietary J1939 CAN traffic so that I can remotely control some actions on a vehicle. I have collected a number of traces covering the events I want to ...
tranzallos's user avatar
2 votes
0 answers
72 views

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 ...
Topa's user avatar
  • 71
3 votes
0 answers
158 views

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:...
Topa's user avatar
  • 71
2 votes
0 answers
127 views

Finding 3-byte checksum algorithm of key transponder

I am developing a tool for programming automotive RFID transponder chips from NXP (e.g. PCF7945, PCF7961). Those chips provide a 3-byte checksum over parts of their internal memory. In order to check ...
Philipp's user avatar
  • 21
2 votes
0 answers
144 views

What's the checksum algorithm for this? Please help to reverse engineer the algorithm

We are trying to make a gadget to interface with Sirius SXV300 module. We are now try to figure out it's communication checksum algorithm. Below are some data in hex strings. Our understanding is that ...
alex369's user avatar
  • 21
2 votes
0 answers
110 views

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
2 votes
0 answers
132 views

Decode this Hotel RFID card lock data checksum

I have hexadecimal data from first 5 blocks of T5557 125KHz RFID card for Chinese made hotel room door lock. The 5th block appear to be some kind of checksum which I like to know how it is derived. ...
Topa's user avatar
  • 71
0 votes
0 answers
104 views

Reverse engineering what seems to be a checksum used for RS232 packets

I will try to be as concise as possible: the issue is, I'm trying to develop a custom application for a dielectric tester. I have access to the original program, which was made some 20 years ago or ...
Davide's user avatar
  • 1
1 vote
1 answer
430 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”. ...
kostinalex's user avatar
2 votes
1 answer
357 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: ...
Avi's user avatar
  • 21
3 votes
2 answers
3k views

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
2 votes
2 answers
222 views

Help with working out a checksum

I'm trying to work out how to reverse engineer the checksum on infrared remote data stream for a heat pump. I've established that it's not a CRC, and I've tried methods found on this forum. It doesn'...
Jonesy's user avatar
  • 31
4 votes
1 answer
416 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
  • 71
2 votes
0 answers
180 views

How to modify checksum after making changes in Nokia 215 4G firmware?

If I change any character in the firmware file and try to flash it, it will failed. But it will successfully flashed if I changed the string with the same number of character if it's not a function. ...
Mohamed's user avatar
  • 21
3 votes
1 answer
321 views

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
  • 31
0 votes
0 answers
35 views

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
960 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
  • 41
0 votes
1 answer
99 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....
ILYA20's user avatar
  • 31