Checksum and verification

Checksum programs are used to generate checksum key strings from the files and verify the integrity of the files later by using that checksum string. A file might be distributed over the network or any storage media to different destinations. Due to many reasons, there are chances of the file being corrupted due to a few bits missing during the data transfer by different reasons. These errors happen most often while downloading the files from the Internet, transferring through a network, CD-ROM damage, and so on.

Hence, we need to know whether the received file is the correct one or not by applying some kind of test. The special key string that is used for this file integrity test is known as a checksum.

We calculate the checksum for the original file as well as the received file. By comparing both of the checksums, we can verify whether the received file is the correct one or not. If the checksums (calculated from the original file at the source location and the...