A hash is a mathematical algorithm that takes any input data, like the words of a song, an image, or even a computer file and produces a fixed-length string that uniquely identifies the original data. Essentially, it’s a kind of digital fingerprint that can be used to verify the integrity of information sent over insecure channels.
Cryptocurrencies like Bitcoin use a hash function to ensure the transaction records are accurate and secure. Every time a new block of transactions is added to the blockchain, a hash value is calculated and included in its header. This hash acts as a reference to the previous block’s hash and can be used to check whether any of the data within the new block was changed. If it is, the hash will change and immediately signal that something is amiss.
A hash has several special properties that make it an essential tool in the world of cybersecurity. One is that it’s deterministic (the same input will always produce the same output), and another is that it has weak collision resistance (any slight modification in the data will result in an entirely different hash value).
