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(storage, communications)
A computed value which depends on the contents of a block of data and which is transmitted or stored along with the data in order to detect corruption of the data. The receiving system recomputes the checksum based upon the received data and compares this value with the one sent with the data. If the two values are the same, the receiver has some confidence that the data was received correctly.

The checksum may be 8 bits (modulo 256 sum), 16, 32, or some other size. It is computed by summing the bytes or words of the data block ignoring overflow. The checksum may be negated so that the total of the data words plus the checksum is zero.

Internet packets use a 32-bit checksum.

See also digital signature, cyclic redundancy check.


A value used to ensure data are stored or transmitted without error. It is created by calculating the binary values in a block of data using some algorithm and storing the results with the data. When the data are retrieved from memory or received at the other end of a network, a new checksum is computed and matched against the existing checksum. A non-match indicates an error.

Just as a check digit tests the accuracy of a single number, a checksum tests a block of data. Checksums detect single bit errors and some multiple bit errors, but are not as effective as the CRC method. Checksums are also used by the Sophos antivirus software to determine if a file has changed since the last time it was scanned for a virus. See ECC memory and Sophos.
References in periodicals archive ?
The calculated CRC16 checksum and the received one are compared.
Checksum 3--Generate nine keys, encrypt all the digits (but the final) with one of these keys, and replace the checksum digits with the checksum plus a key identifying value from 1 to 9.
The TCP checksum field is used to ensure the correct transmission of the data.
This is achieved through a combination of manual and automated spam analysis that includes real-time black lists, Lexical analysis tests, textual content characteristics, header information, Bayesian probability techniques, Distributed Checksum Clearinghouse, centralised analysis and customer controlled lists.
Q WHENEVER I power-up my lap-top computer the following error occurs: 0271 - Check Date and Time Settings, WARNING 0251 - System CMOS checksum bad - Default configuration used.
The adapters support TCP/IP checksum hardware offloading, auto-negotiation/ autosensing, dual voltage, jumbo frame support and dynamic interrupt moderation.
This is a technique used to compute a "checksum" of the information, encrypt the checksum, and attach the encrypted checksum to the information.
Contract awarded for Checksum small rural district water development projects basic research services
grading, plus verified copying, faster-than-realtime encoding of multiple deliverables, plus checksum verified ingest, copying and archival via the Copy Central (TM) capability.
Yet that is exactly what the president and chief executive of CheckSum (checksum.
This is achieved by generating the checksum for important files which, at regular intervals, is checked against the current version of the file.