Checksum: Difference between revisions

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[[File:Checksum.svg|thumb|330px|right|Effect of a typical checksum function (the Unix <tt>[[cksum]]</tt> utility)]]
 
A '''checksum''' is a small-sized [[datum]] derived from a [[Block (data storage)|block]] of [[digital data]] for the purpose of [[error detection|detecting errors]] that may have been introduced during its [[telecommunication|transmission]] or [[computer storage|storage]]. By themselves, checksums are often used to verify data integrity but are not relied upon to verify data [[authentication|authenticity]].
 
The [[algorithm|procedure]] which generates this checksum is called a '''checksum function''' or '''[[checksum algorithm]]'''. Depending on its design goals, a good checksum algorithm will usually output a significantly different value, even for small changes made to the input. This is especially true of [[cryptographic hash function]]s, which may be used to detect many data corruption errors and verify overall [[data integrity]]; if the computed checksum for the current data input matches the stored value of a previously computed checksum, there is a very high probability the data has not been accidentally altered or corrupted.