hashkódolást

Hashkódolás, more commonly known as hashing, is a process that transforms an arbitrary amount of data into a fixed-size string of characters, known as a hash value or hash code. This hash value acts as a unique fingerprint for the original data. Even a minor alteration to the input data will result in a significantly different hash value, a property known as the avalanche effect. Hash functions are designed to be one-way; it is computationally infeasible to reverse the process and reconstruct the original data from its hash value. This one-way nature is crucial for many of its applications.

The primary uses of hashkódolás include data integrity checks and password storage. When a file or message is transmitted, its hash value can be calculated and sent alongside it. The recipient can then recalculate the hash value of the received data and compare it to the provided hash. If the values match, it indicates that the data has not been tampered with during transit. For password storage, instead of storing user passwords in plain text, their hash values are stored. When a user attempts to log in, their entered password is hashed, and the resulting hash is compared to the stored hash. This prevents unauthorized access to actual passwords even if the database is compromised. Other applications include data indexing in hash tables, digital signatures, and message authentication codes.