CRC-32
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.
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Specific algorithms
Selected CRC-32 algorithms are listed here. The names are from the CRC RevEng Catalogue.
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.
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.
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.
Others
Other members of the CRC-32 family include CRC-32Q, CRC-32C (Castagnoli), and CRC-32K (Koopman).
Links
- CRC RevEng: Catalogue of parametrised CRC algorithms - 32 bits
- CRC Polynomial Zoo - 32 Bits
- ITU-T Rec. V.42 Section 8.1.1.6.2 (IEEE CRC-32)
- Rosetta Code: CRC-32
See also CRC#Links.
