Symmetric Cryptography
Symmetric cryptography, also called private-key cryptography, uses a single key to both encrypt and
decrypt a message. This method is generally inappropriate for securing data that will be used by a
third party because of the complexity of secure key exchange. Symmetric cryptography is generally
useful for encrypting data for one??™s own purposes.
A classic use of symmetric cryptography is for a personal password vault. Anyone who has been
using the Internet for any amount of time has accumulated a quantity of usernames and passwords
for accessing various sites and resources. A personal password vault lets you store this access information
in an encrypted form. The end result is that you have to remember only one password to
unlock all of your access information.
Exporting Encryption Technology
Before describing how to use the various encryption tools, I need to warn you about an unusual policy
of the United States government. For many years, the United States government treated encryption
technology like munitions. As a result, anyone wanting to export encryption technology had to
get an export license from the Commerce Department. This applied not only to encryption software
developed within the United States, but also to software obtained from other countries and then reexported
to another country (or even to the same country you got it from).
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