Hashprüfung

Hashprüfung, also known as hash checking or hash verification, is a process used to ensure the integrity and authenticity of digital data. It involves calculating a cryptographic hash value of a file or message and then comparing this calculated hash with a known, trusted hash value. If the two hash values match, it strongly indicates that the data has not been altered or corrupted since the original hash was generated.

A cryptographic hash function takes an input of any size and produces a fixed-size output, known as a hash value or digest. These functions are designed to be one-way, meaning it is computationally infeasible to reverse the process and derive the original data from its hash. They are also designed to be deterministic, so the same input will always produce the same hash output. Furthermore, even a small change in the input data should result in a significantly different hash output, a property known as the avalanche effect.

Hashprüfung is commonly used in various applications. For instance, when downloading software or files from the internet, the provider often publishes a checksum or hash value. Users can then calculate the hash of the downloaded file on their own system and compare it to the provided hash. A match confirms the download was successful and the file is as intended. It is also vital in data storage, ensuring that data remains unchanged over time, and in digital forensics, to maintain the chain of custody for evidence.