A cyclic redundancy check (CRC) is an error-detecting code designed to detect accidental changes to raw computer data, and is commonly used in digital networks. (wiki) A CRC32 algorithm typically takes in a file stream or character array and calculates an unsigned long codeword from the input. One can transmit this codeword and re-calculate it on the receiver end, then compare it to the transmitted one to detect an error.
A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data. Blocks of data entering these systems get a short check value attached, based on the remainder of a polynomial division of their contents; on retrieval the calculation is repeated, and corrective action can be taken against presumed data corruption if the check values do not match. wikipedia
The most commonly used polynomial lengths are:
- CRC-8: 9 bits
- CRC-16: 17 bits
- CRC-32: 33 bits
- CRC-64: 65 bits
A truly excellent tutorial on CRC's is Ross Williams' "Painless Guide to CRC Detection Algorithms", which can also be found here, here, here, here, and here.
