Nearly every web application you use that stores a password of yours, should store your credentials in some form of hashed format for added security. A good hashing system in place for user passwords can be very useful in case your database is ever stolen, as this will extend the time taken for a hacker to crack them.

For this reason, we have numerous different hashing methods, some of which are reused throughout different applications, such as MD5 and SHA hashes, but some such as Des(UNIX) are less commonly found. Because of this, it is a good idea to be able to match a hash value to the hashing function it belongs to. We cannot base this purely on hash length as many hashing functions share the same length, so to aid us with this we are going to use regular expressions (Regex). This allows us to define the length, the characters used, and whether any numerical values are present.