A hashing function is used to calculate a hash value. If you insert a file into a hashing function then it should produce a value that is almost certain to be unique (there’s always the remote likelihood that no matter how good your function, you may end up with a duplicate). The openssl command is used to access a number of functions/ciphers including sha1, base64, md5, rc4/rc5 and of course des/des3. It is a very simple command to use, simply provide the cipher, followed by the path to the file you would like to get a hash value (aka digest) for. So if I have a file called myfile.txt and I would like to get a digest for it I could just use the following command: openssl md5 myfile.txt At its most basic level, we’re just leveraging openssl to grab digests quickly and easily.