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checksum

   Also found in: Dictionary/thesaurus, Wikipedia, Hutchinson 0.01 sec.

checksum

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.

(storage, communications)checksum - 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.


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? Mentioned in ? References in periodicals archive
 
Assureon assigns a global unique serial number to each file and the contents must match a checksum comparison to pass the audit.
Nexsan Assureon appliance solves security, business continuity and ... by Murphy, Dan / Computer Technology Review
The embedded Agent can check the security status of the embedded device including: the status of executables (antivirus, host firewall, host IDS, sandbox), files (antivirus signatures, host firewall policies, host IPS signatures, MD5 checksum, file version), registry values, versions, patches, and operating system configurations.
Sygate introduces next phase of endpoint security solution for ... by EDP Weekly's IT Monitor
If any bit in the message is altered during transmission, the checksum would be different.
Sneaky calculations: how to trick other people's computers into ... by Peterson, Ivars / Science News
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