Bibliography/ref/link

Introduction to cryptography
The Code Book, Simon Singh (ISBN 1-85702-889-9)
Applied Cryptography, Bruce Schneier (ISBN (fr) 2-84180-036-9)
http://www.foo.be/docs-free/applied-cryptography/
Introduction to Cryptography with Coding Theory (0-13-061814-4)
Cryptography and network security protocol
Network Security Essentials, William Stallings (ISBN 0-13-016093)
OpenPGP Message Format, RFC-2440 ftp://ftp.isi.edu/in-notes/rfc2440.txt
GNU privacy Guard http://www.gnupg.org/gph/en/manual.html
Advanced cryptography and cryptosystem 
Modelling and analysis of security protocols, Peter Ryan (ISBN 0-201-67471-8)
Making, Breaking Codes: Introduction to Cryptology, Paul Garrett (0-13-030369-0)