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Questions tagged [checksum]

A checksum or hash sum is a fixed-size datum computed from an arbitrary block of digital data for the purpose of detecting accidental errors that may have been introduced during its transmission or storage. The integrity of the data can be checked at any later time by recomputing the checksum and comparing it with the stored one.

A checksum or hash sum is a fixed-size datum computed from an arbitrary block of digital data for the purpose of detecting accidental errors that may have been introduced during its transmission or storage.

The integrity of the data can be checked at any later time by recomputing the checksum and comparing it with the stored one. This process doesn't guarentee the data hasn't been corrupted, but is a good indication.

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Efficient whole file CRC computation in the presence of small overwrites

I have a large file and I maintain crc32 checksum over its contents. If a fixed portion of the file were to change either at the start of the file or the end of the file, I can maintain crc32 checksum of the static portion and the dynamic portion…
Nitin Muppalaneni
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Is there a solution to fix SVN checksum mismatch permanently?

I have almost searched all the solutions on the internet of the SVN checksum mismatch problem. The most useful solution for now is as follows: svn-checksum-mismatch-while-updating But all the solutions now are just curing the symptoms, not the…
Phymin
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checksum of a file in javascript

I have a use case where if a user uploads a file and then before it gets uploaded, I want to calculate a checksum on that file within the browser. I found couple of libraries but for files more than 3 GB, the calculation time is too much so was…
Bhavya Bansal
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variable bit length non-cryptographic hash/checksum

In the "Small Collision Probabilities" section of https://preshing.com/20110504/hash-collision-probabilities/ you can see the trade-offs depending on how big the hash value is. Rather a 32-bit or 160-bit hash depends on your use-case and…
ParoX
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Is there a 8/16/32 checksum algorithm that will yield a result that is not equal to all FFs or zeros?

I would like to calculate a checksum (preferable 8 bit) that will yield a result that is not FF and not 0. It is to be used in a circular log SPI flash file system for a microcontroller. In the file system 0 marks the start of a record, and FF…
Armand Jordaan
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How to calculate the number of same elements in 2D arrays in Python?

Now I have two 2D arrays, I want to compare ['A','B','E','G', 'T'] & ['A','C','E','N','M'] ['a','f','c','h','u'] & ['a','b','c','y','l'] and calculate the same elements. aaa = [['A','B','E','G','T'],['a','f','c','h','u']] bbb =…
Cecilia
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PowerShell exact column comparison

I have two text file and in this txt files there is an MD5 checksums of some backup files. I am trying to compare these text files and if MD5 is same I am try to adding near "-2" if it is different adding "-1" but the problem is directories are…
William Kendly
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i want checksum promng for these data " 1B 02 1D 01 01 0B 03'' I want these data a python software. output should be B0h

i want checksum programming in python language. data is "1B 02 1D 01 01 0B 43 6F 64 50 61 64 20 54 65 78 74 1B 03 " Output should be - B0h. ( ascii to hexadecimal convertion ) .
RD Indigo
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CRC-CCITT 16 bit Calculation in C#

I am trying to write one program for serial port communication, where i need to send data packet with CRC, I am writing this code in C# language. Below is sample packet which receiver is expecting with CRC. 10 02 B1 F0 3F 32 08 00 00 10 03 B4…
Suresh
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Swift plist checksum

I would like to calculate and validate some checksums of a property list in iOS. The contents of the plist are the following:
Bram
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Calculating the TCP checksum value - TCP Length & Padding

I'm attempting to calculate the TCP checksum value (which apparently is the same as the IP4 checksum) but getting the wrong results. I think the issue is arrising from either the padding at the end or the TCP header field but I can't find any…
Crizly
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Calculating the BCC for the 3964r serial communications protocol

I am trying to write some code to communicate with an old device over serial that uses the Siemens 3964r protocol. This includes a checksum, or more accurately a BCC (block check character) at the end of the transmission. A single char after the…
wookie924
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Checksum for a self-made communication protocol

I have to implement a communication protocol which runs via I2C and is used for a board2board communication of two distributed microcontrollers. To ensure the data integrity, I want to add to the communication protocol a checksum and thought…
user9564464
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Self-validating encrypted string - is method feasible?

I have a keystring which allows customer to have additional features. Obviously I would like the software to check that this string is valid, and not modified. Is the following idea feasible: get the key string as encrypted value, and encode it…
MyICQ
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Is there method to predict outer UDP checksum from inner UDP checksum

In a tunneled packet there may exist two UDP headers. One outer UDP and one inner UDP e.g MAC + outerIP + outerUDP + extraheader + innerIP + innerUDP + payload. Inner UDP has its own checksum. Is there an optimized way to calculate outerUDP checksum…
Asam Padeh
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