hashovací

Hashování, also known as hashing, is a process that transforms an input of arbitrary size into a fixed-size output. This output is called a hash value, hash code, digest, or simply hash. Hash functions are mathematical algorithms that perform this transformation. They are designed to be fast to compute and computationally infeasible to reverse, meaning it's difficult to determine the original input from its hash value.

One of the key properties of a good hash function is that even a small change in the input should result in a significantly different hash value. This is known as the avalanche effect. Hash functions are widely used in computer science for various purposes. In data integrity checks, hashing allows for verifying that data has not been altered. By comparing the hash of a file before and after transmission or storage, one can detect any modifications.

Hashing is also crucial in cryptography for digital signatures and password storage. Instead of storing passwords directly, systems store their hash values. When a user attempts to log in, their entered password is hashed, and the resulting hash is compared to the stored hash. This prevents attackers from obtaining actual passwords even if they gain access to the database.

Another common application is in hash tables, a data structure that uses hash functions to map keys to values, enabling efficient data retrieval. Hash functions are also employed in data deduplication to identify identical files or data blocks, and in blockchain technology to ensure the integrity and immutability of transaction records.