Checksum
A checksum or hash sum is a small-size datum from a block of digital data for the purpose of detecting and correcting errors which may have been introduced during its transmission or storage.
Contents
Description
A checksum is usually applied to an installation file after it is received from the download server.
Integrity and authenticity
By themselves checksums are often used to verify data integrity, but should not be relied upon to also verify data authenticity.
Functions and algorithms
The actual procedure which yields the checksum, given 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 functions, 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.
Similar concepts
Similar concepts, each with its own applications and design goals, include:
- hash functions
- Fingerprints
- Randomization functions
- Cryptographic hash functions
Cryptographic primitives
Checksums are used as cryptographic primitives in larger authentication algorithms.
Check digits and parity bits
Check digits and parity bits are special cases of checksums, appropriate for small blocks of data (such as Social Security numbers, bank account numbers, computer words, single bytes, etc.).
Data recovery
Some error-correcting codes are based on special checksums which not only detect common errors but also allow the original data to be recovered in certain cases.
See also
- Checksum function
- Computer science
- Computing
- Cryptography
- Data authenticity
- Data integrity
- Data storage
- Data structure
- Data transmission
- Error detection and correction
- Hash function
- Mathematics
External links
- Checksum @ Wikipedia
