## What is CRC32?

CRC32 is one of hash functions based on on the "polynomial" division idea.
The CRC is acronym for **C**yclic **R**edundancy **C**ode (other
variants instead "Code" is "Check" and "Checksum") algorithm. The number 32
is specifying the size of resulting hash value (checksum The value calculated from content of file. There is several algorithms for do this - CRC32, MD5, SHA-1...)
- 32 bits. The checksum is used to detect errors after transmission or
storage of any piece of information.

### Cyclic redundancy check

Cyclic redundancy checksum (CRC) is the remainder of a binary division with no bit carry (XOR used instead of subtraction), of the message bit stream, by a predefined (short) bit stream. In short, take the data as a VERY long binary number and divide it by a constant divisor. Although such tasks can seems too complex and requiring the specialized libraries to work with very long numbers, but actually there are simple, efficient algorithms for computing this remainder.

While useful for error detection, CRCs cannot be safely relied upon to verify data integrity (that no changes whatsoever have occurred), since, because of the linear structure of CRC polynomials, it is extremely easy to intentionally change data without modifying its CRC. Cryptographic hash functions, such as MD5 MD5 is secure cryptographic checksum (message digest, hash) algorithm. RFC 1321 contains MD5 algorithm description and reference implementation of MD5 too. Used by MD5SUM utility. or SHA-1 (Secure Hash Algorithm) designed by the National Security Agency (NSA) in 1993 as the algorithm of the Secure Hash Standard (SHS, FIPS 180)., can be used to verify data integrity.

### About AccuHash 2.0

**AccuHash 2.0** (the Windows utility for protecting the integrity and
verifying the accuracy of data files) currently support
CRC32 One of checksum calculation algorithms family based on Cyclic Redundancy Codes. CRC32 is used in SFV checksum file format, produced by many checksum utilities. CRC32 is not secure and easily can be forged.
checksums.
Latest version of AccuHash is 2.0.18 - ah2setup.exe (968Kb) from November 06, 2008.