hashfunktsiooni

A hash function, or hashfunktion in Estonian, is a mathematical algorithm that maps data of arbitrary size to data of a fixed size. This fixed-size output is known as a hash value, hash code, digest, or simply hash. The process of converting input data into a hash value is called hashing. Hash functions are fundamental to many areas of computer science, including cryptography, data structures, and error detection.

Key properties of good cryptographic hash functions include determinism, meaning the same input will always produce the same output. They should also be computationally efficient to compute. Ideally, hash functions exhibit the avalanche effect, where a small change in the input data results in a significant change in the output hash value. Resistance to collisions is another crucial characteristic; it should be computationally infeasible to find two different inputs that produce the same hash output.

Common applications of hash functions include verifying data integrity, where hashing can detect accidental corruption or malicious tampering. In cryptography, they are used in digital signatures and password storage, where storing the hash of a password instead of the password itself enhances security. Hash functions also form the backbone of hash tables, a data structure that allows for efficient data retrieval by mapping keys to indices in an array.