CRC is a computational method that's complicated to check out properly a the digital transmission on a connection of communication, or to ensure, malfunctioning, and the integrity of a file stored on the hard disk . The computer transmitter is one of the formula multiple to calculate an amount of the information available in the data used. and the amount of the block containing the message before being sent message is added .The computer, receiver, computing the same on the same data performs, and this number, together with the CRC received, compared . If the two CRC match together dies. represents an error of transmission. and the computer receiver computer to the sender a request to send data again. This procedure as a check of redundancy is known, because, as in every transfer, we own the data we have, including the values, check additional error, or added. As a security survey, a CRC it is possible to compare the size of the executable file against the original size to determine whether the file has been tampered or in any way altered is used.
the validity of the above method is very high and very widely used.