Message Digest (MD) can be translated as "news summary" and refers to a specific group of one-way hash functions. The online tools can generate MD2, MD4, and MD5 hashes free of charge. The message digest hash functions have to claim that it is not possible to restore the original text by a hash value. In addition, it shall not be possible to calculate a text to the same hash value as the original generated (collisions should not exist). However, there are currently no MD algorithms that can guarantee freedom from collisions.