The heart of SSL – as well
as pretty much every other computer security or encoding system – is something called a
. The first article below describes how a public key encryption scheme works,
and the second explains the mathematics behind it: prime numbers and mod
1. A Primer on Public-key Encryption
Adapted from a suppliment to The Atlantic magazine, September 2002. By Charles Mann.
Public-key encryption 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 few terms first: cryptology, the study of codes and ciphers, is the union of cryptography
(codemaking) and cryptanalysis (codebreaking). To cryptologists, codes and ciphers are not the
same thing. Codes are lists of prearranged substitutes for letters, words, or phrases – i.e. "meet
at the theater" for "fly to Chicago." Ciphers employ mathematical procedures called algorithms to
transform messages into unreadable jumbles. Most cryptographic algorithms use keys, which are
mathematical values that plug into the algorithm.