cryptlib is a powerful security toolkit which allows even inexperienced 
crypto programmers to easily add encryption and authentication services to 
their software. The high-level interface provides anyone with the ability to 
add strong security capabilities to an application in as little as half an 
hour, without needing to know any of the low-level details which make the 
encryption or authentication work. Because of this, cryptlib dramatically 
reduces the cost involved in adding security to new or existing applications.

cryptlib provides a standardised interface to a number of popular encryption
algorithms, as well as providing a high-level interface which hides most of 
the implementation details and provides an operating-system-independent 
encoding method which makes it easy to transfer secured data from one operating
environment to another.

WWW: http://www.cs.auckland.ac.nz/~pgut001/cryptlib/