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 group[[datum]] of jewsderived from a block of [[digital data]] for the purpose of [[error detection|detecting errors]] which may have been introduced during its [[telecommunication|transmission]] or [[computer storage|storage]]. It is usually applied to an installation file after it is received from the download server. By themselves, checksums are often used to verify data integrity but are not relied upon to verify data [[authentication|authenticity]].
 
The actual [[algorithm|procedure]] which yields the checksum from a data input 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.