Abbreviated CRC. A complex calculation method used to check the accuracy of a digital transmission over a communications link or to ensure the integrity of a file stored on a hard disk.
The sending computer uses one of several formulas to calculate a value from the information contained in the data, and this value is appended to the message block before it is sent. The receiving computer performs the same calculation on the same data and compares this number with the received CRC. If the two CRCs do not match, indicating a transmission error, the receiving computer asks the sending computer to retransmit the data.
This procedure is known as a redundancy check because each transmission includes extra or redundant error-checking values as well as the data itself.
As a security check, a CRC may be used to compare the current size of an executable file against the original size to determine if the file has been tampered with or changed in some way.