The hash of a file or of a text is like a digital fingerprint. It is unique: each file has its own hash. Non è “invertibile”: dall’hash non si può risalire al file o al testo che lo ha generato. Just change a text of a comma or a photo of a pixel and this change will radically and absolutely unpredictably change its hash. There are several online services that provide free hashing. Being a service based on a mathematical function, if the file has not changed and if you are using the same hashing algorithm, the result will always be the same! For your convenience, we made available one for the files (qui) and one for the text strings (qui) both based on the SHA256 algorithm.