Cryptography FAQ

If you are looking for a reference to understand Cryptography the following is a good starting point:
Crypto FAQ
It does not provide details on all the concepts and as the title says, it is just an FAQ and gives you an overall view of all the cryptography jargon!

A PDF version is available at:
ftp://ftp.rsasecurity.com/pub/labsfaq/rsalabs_faq41.pdf
or
http://www.rsasecurity.com/rsalabs/faq/files/rsalabs_faq41.pdf