Checksumlike

Checksumlike is a broad, informal designation for data integrity methods that map arbitrary input data to a small, fixed-size value intended to detect errors or changes. The class is loosely defined; unlike formal cryptographic hash functions, checksumlike methods prioritize speed and simplicity over resistance to malicious tampering. Outputs are called digests or checksums, and may be appended to data or used in streaming fashion.

Common examples include simple modular sums, parity, CRCs, and other non-cryptographic digests such as Adler-32 or Fletcher checksums. They are deterministic: the same input yields the same digest. Some are incremental, allowing updates as data streams are processed, which makes them suitable for network protocols and file processing.

Uses include error detection in storage systems, network frames, software build validation, and data backups. They help detect accidental bit flips, transmission errors, or data corruption.

Limitations: checksumlike methods are not designed to resist intentional manipulation; collisions do occur, and they are not suitable for cryptographic integrity or authentication. They should not replace cryptographic methods in security-critical contexts, as attackers can often craft inputs that produce the same digest.

Terminology: “checksumlike” is not a formal standard and can refer to methods that resemble checksums in form or function but may differ in algorithm and properties.

See also: checksum, CRC, hash function, parity, error detection.