Password Based Cryptography

A password is not just a word or string of characters but is the most important factor used for user authentication to prove identity or access approval to gain access to a resource, which is to be kept secret from those not allowed access. As passwords are often chosen without paying much attention special care is required in the process of protection from attacks. A lot of systems attempt to derive a cryptographic key directly from a password and this is to dangerous for the security of users accounts. Password based cryptography is usually defined as some form of guarantee against brute force attacks. Nowadays exist many approaches about password based cryptography and a lot of researchers have given their contribution in this field. My aim is to analyze these approaches and to find the best techniques used for this kind of cryptography. We will see that some techniques should be improved and some other are relatively expensive.