Very poor encryption

Here is a story about a portable hard drive that claims to use 128-bit AES encryption, but only uses a extremely week XOR function for data security.

Graphs

What does the internet look like?
Possible email paths.

Relatively prime numbers

Mathwords: Relatively Prime
Relavively Prime - Mathworld

flow chart of an email

Flow Chart

RSA links

Prime Number Hide-and-Seek: How the RSA Cipher Works
RSA Algorithm
A New Vulnerability In RSA Cryptography

Book:
Schneier, Bruce (1995-10-09). Applied Cryptography. New York: Wiley, 587. ISBN 0471117099.

How e-mail encryption links to discrete math and computer science:

• E-mail encryption
• Encryption
• Algorithms
• First used: RSA
• Others: ElGamal, DES, AES, 3DES, Blowfish, Twofish, CAST5, MD5, SHA-1, RIPE-MD-160 and TIGER
• Networks
• Graph Theory
  

An overview of e-mail privacy problems(Wikipedia).

The problem with taking your passwords to your grave.

How to tell if the NSA is reading your e-mail.

Secure / Multipurpose Internet Mail Extensions (S/MIME), an overview of the protocol used to encapsulate an encrypted/signed message in an e-mail.