Raaz is a cryptographic library which provides the state of the art cryptographic primitives via a high-level, type safe interface. The default interface provided to the user is through the top level module Raaz. Rather than bothering the user with low-level details like the selection of primitives or entropy sources, this top level module only talks about the desired cryptographic operation (whether it is message digest or message encryption etc). A standalone application that needs cryptography should stick to using this top level interface. Sometimes the selection of primitives is not in our hands --- we may need to interface with other programs written in other languages or using other libraries. For such situation, raaz exposes a primitive specific interface. As an example raaz exposes the Raaz.Digest.Sha256 module that gives the same interface as that of Raaz.Digest but uses sha256 as the underlying cryptographic hash.