Stack Overflow
Stack Overflow

Questions tagged [crc]

Cyclic redundancy check. An error checking mechanism used for verifying data integrity in serial protocols.

1120 questions
18
votes
1 answer

What is cyclic redundancy check and how it works in simple terms (for-dummies style)?

I'm having trouble understanding the concept and workings of the ugly sounding term "cyclic redundancy check". I'm attending a college course on Computer Networks and I'm getting lost already. The trouble is that my understanding of mathematics is…
Boyko Arsov
  • 341
  • 1
  • 5
  • 12
18
votes
4 answers

Is it possible to do rudimentary error correction with CRC?

I know the whole intention of using CRC is to do error detection, but I heard someone state that it can be used to do basic error correction in addition to error detection. I was curious if this was the case, and if so, how powerful is it? I mean,…
naivedeveloper
  • 2,814
  • 8
  • 34
  • 43
18
votes
2 answers

Fast CRC algorithm?

I want to create a 32-bit number out of an ASCII-string. CRC32 algorithm is exactly what I'm looking for, but I can't use it because the table it requires is way too huge (it is for an embedded system where resources are VERY rare). So: any…
Elmi
  • 5,899
  • 15
  • 72
  • 143
18
votes
7 answers

CRC32 Collision

I am trying to find a collision between two messages that will lead to the same CRC hash. Considering I am using CRC32, is there any way I can shorten the list of possible messages I have to try when doing a brute force attack? Any links to websites…
Mike
18
votes
4 answers

Reversing CRC32

I'm looking for a way to reverse a CRC32 checksum. There are solutions around, but they are either badly written, extremely technical and/or in Assembly. Assembly is (currently) beyond my ken, so I'm hoping someone can piece together an…
pat
  • 16,116
  • 5
  • 40
  • 46
17
votes
2 answers

Get CRC checksum of an NSData in Objective-C

How can I count CRC (32 or 64) of an NSData object in Objective-C? Thanks in advance!
Knodel
  • 4,359
  • 8
  • 42
  • 66
17
votes
1 answer

Is there a C#/.NET standard implementation of CRC?

I know that implementations exist for SHA-1 and SHA-256 in System.Security.Cryptography. Is there anything built in that can compute CRC hashes?
Pugz
  • 939
  • 3
  • 11
  • 25
17
votes
1 answer

How is PNG CRC calculated exactly?

For the past 4 hours I've been studying the CRC algorithm. I'm pretty sure I got the hang of it already. I'm trying to write a png encoder, and I don't wish to use external libraries for the CRC calculation, nor for the png encoding itself. My…
MythicManiac
  • 445
  • 1
  • 4
  • 11
15
votes
5 answers

C# CRC implementation

I am trying to integrate a Serial-port device into my application, which needs CRC-CCTT validation for the bytes that I send to it. I'm kinda new into managing byte packets, and need help for this. It uses this formula for making the CRC…
Mg.
  • 1,469
  • 2
  • 16
  • 29
13
votes
1 answer

Storing CRC into an AXF/ELF file

I'm currently working on a C program in the LPCXpresso (eclipse-based) tool-chain on Windows 7, an IDE with gcc targeting the an NXP Cortex M3 microprocessor. It provides a simple way to compile-link-program the microprocessor over JTAG. The…
superlou
  • 679
  • 1
  • 8
  • 21
12
votes
1 answer

Basic CRC32 Wikipedia implementation differs from standard CRC32 seen online

I have a basic CRC32 implementation following Wikipedia's Code Fragment:1 sample. I think I have done it right, with the modification of using an n-bit register for the remainderPolynomial instead of n+1 bit usage as per the example. The result I…
Titus
  • 907
  • 8
  • 18
12
votes
2 answers

How to get CRC64 distributed calculation (use its linearity property)?

I need hash over pretty large files which is stored on distributed FS. I'm able to process parts of file with much more better performance than whole file so I'd like to be able to calculate hash over parts and then sum it. I'm thinking about CRC64…
Roman Nikitchenko
  • 12,800
  • 7
  • 74
  • 110
11
votes
1 answer

Finding which Checksum is used

Together with some other people we are trying to make a Savegameeditor for a game, but we came accross some problems. The savegame files contain a kind of checksum,of which we can't seem to find which checksum is used for this. Till now all we know…
Joey
  • 176
  • 2
  • 12
11
votes
3 answers

Calculate/validate bz2 (bzip2) CRC32 in Python

I'm trying to calculate/validate the CRC32 checksums for compressed bzip2 archives. .magic:16 = 'BZ' signature/magic number .version:8 = 'h' for Bzip2 ('H'uffman coding) .hundred_k_blocksize:8 =…
soulseekah
  • 8,770
  • 3
  • 53
  • 58
11
votes
4 answers

CRC16 checksum: HCS08 vs. Kermit vs. XMODEM

I'm trying to add CRC16 error detection to a Motorola HCS08 microcontroller application. My checksums don't match, though. One online CRC calculator provides both the result I see in my PC program and the result I see on the micro. It calls the…
Potatoswatter
  • 134,909
  • 25
  • 265
  • 421
1
2
3
…
74 75