Ok, this isn't econ, but an interesting read anyway...

The Atlantic | September 2002 | Homeland Insecurity | Mann

A Web-only Primer on Public-key Encryption

Public-key encryption, as noted in the profile of cryptographer Bruce Schneier, is complicated in detail but simple in outline. The article below is an outline of the principles of the most common variant of public-key cryptography, which is known as RSA, after the initials of its three inventors...

A primer on public-key encryption | Posted September 3, 2002 10:36 AM by John Irons