CRC-32

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'''CRC-32''' is a family of 32-bit hash functions used to detect accidental data corruption.
 
'''CRC-32''' is a family of 32-bit hash functions used to detect accidental data corruption.
  
The term ''CRC-32'' by itself usually means the IEEE CRC-32 algorithm. Other members of the CRC-32 family include CRC-32Q, CRC-32C (Castagnoli), and CRC-32K (Koopman).
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The term ''CRC-32'' by itself usually means the CRC-32/ISO-HDLC (IEEE) algorithm.
  
== See also ==
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Refer to the [[CRC]] article for more information.
* [[CRC]]
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== Specifications ==
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== Specific algorithms ==
* [http://www.itu.int/rec/T-REC-V.42/en ITU-T Rec. V.42] Section 8.1.1.6.2 (IEEE CRC-32)
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Selected CRC-32 algorithms are listed here. The names are from the CRC RevEng Catalogue.
  
== Software ==
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=== CRC-32/ISO-HDLC ===
* [http://rosettacode.org/wiki/CRC-32 Rosetta Code: CRC-32]
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Also referred to as ISO 3309, ITU-T V.42, CRC-32-IEEE, and many other names.
  
There seems to be no widely available Unix utility that computes a standard CRC-32. The POSIX '''cksum''' utility does ''not'' use the standard CRC-32 algorithm.
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The CRC of ASCII "<code>123456789</code>" is <code>0xcbf43926</code>.
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Examples of formats that use CRC-32/ISO-HDLC: [[ZIP]], [[PNG]], [[Gzip]], [[ARJ]].
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=== CRC-32/JAMCRC ===
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Equivalent to CRC-32/ISO-HDLC, but with the final CRC's bits inverted (or, rather, ''not'' inverted -- ISO-HDLC is the one that inverts the bits).
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The CRC of ASCII "<code>123456789</code>" is <code>0x340bc6d9</code>.
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Examples of formats that use CRC-32/JAMCRC: [[EDI Install archive]] and [[Eschalon Setup archive]], [[Brik]].
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=== CRC-32/CKSUM ===
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The default algorithm of the traditional Unix/POSIX "cksum" utility. Note that the utility uses a high-level algorithm that preprocesses the input data.
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The (high-level) CRC of ASCII "<code>123456789</code>" is <code>0x377a6011</code>.
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=== Others ===
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Other members of the CRC-32 family include CRC-32Q, CRC-32C (Castagnoli), and CRC-32K (Koopman).
  
 
== Links ==
 
== Links ==
* [[Wikipedia:Cyclic redundancy check|Wikipedia: Cyclic redundancy check]]
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* [https://reveng.sourceforge.io/crc-catalogue/17plus.htm#crc.cat-bits.32 CRC RevEng: Catalogue of parametrised CRC algorithms - 32 bits]
* [http://www.infinitepartitions.com/cgi-bin/showarticle.cgi?article=art008 Understanding CRC32]
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* [https://users.ece.cmu.edu/~koopman/crc/crc32.html CRC Polynomial Zoo - 32 Bits]
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* [https://www.itu.int/rec/T-REC-V.42/en ITU-T Rec. V.42] Section 8.1.1.6.2 (IEEE CRC-32)
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* [https://rosettacode.org/wiki/CRC-32 Rosetta Code: CRC-32]
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See also [[CRC#Links]].

Latest revision as of 13:05, 4 April 2023

File Format
Name CRC-32
Ontology

CRC-32 is a family of 32-bit hash functions used to detect accidental data corruption.

The term CRC-32 by itself usually means the CRC-32/ISO-HDLC (IEEE) algorithm.

Refer to the CRC article for more information.

Contents

[edit] Specific algorithms

Selected CRC-32 algorithms are listed here. The names are from the CRC RevEng Catalogue.

[edit] CRC-32/ISO-HDLC

Also referred to as ISO 3309, ITU-T V.42, CRC-32-IEEE, and many other names.

The CRC of ASCII "123456789" is 0xcbf43926.

Examples of formats that use CRC-32/ISO-HDLC: ZIP, PNG, Gzip, ARJ.

[edit] CRC-32/JAMCRC

Equivalent to CRC-32/ISO-HDLC, but with the final CRC's bits inverted (or, rather, not inverted -- ISO-HDLC is the one that inverts the bits).

The CRC of ASCII "123456789" is 0x340bc6d9.

Examples of formats that use CRC-32/JAMCRC: EDI Install archive and Eschalon Setup archive, Brik.

[edit] CRC-32/CKSUM

The default algorithm of the traditional Unix/POSIX "cksum" utility. Note that the utility uses a high-level algorithm that preprocesses the input data.

The (high-level) CRC of ASCII "123456789" is 0x377a6011.

[edit] Others

Other members of the CRC-32 family include CRC-32Q, CRC-32C (Castagnoli), and CRC-32K (Koopman).

[edit] Links

See also CRC#Links.

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