 For the production of small amounts of keying material, ordinary dice provide a good source of high quality randomness.For most computer security purposes and for most users, "key" is not synonymous with "password" (or "passphrase"), although a password can in fact be used as a key.The primary practical difference between keys and passwords is that the latter are intended to be generated, read, remembered, and reproduced by a human user (though the user may delegate those tasks to password management software).