Have you ever wondered if your email can be read during its transmission
from you to other people, or from other people to you? Unfortunately,
complete strangers could conceivably intercept or even tamper with your
email.
In traditional (also known as "snail") mail, letters are usually sealed
within envelopes, stamped and delivered from post office branch to
branch until they reach their destination. But sending mail through the
Internet is much less secure; email is usually transmitted as
unencrypted text from server to server. No special steps are taken to
protect your correspondence from being seen or tampered with by other
people.
To help you protect your privacy, Red Hat Linux 7.2 includes
GnuPG, the GNU Privacy
Guard, which is installed by default during a typical
Red Hat Linux installation. It is also referred to as GPG.
GnuPG is a tool for secure communication; it
is a complete and free replacement for the encryption technology of PGP
(Pretty Good Privacy, a widely popular encryption application). Using
GnuPG, you can encrypt your data and
correspondence, and authenticate your correspondence by
digitally signing your
work. GnuPG is also capable of decrypting and
verifying PGP 5.x.
Because GnuPG is compatible with other
encryption standards, your secure correspondence will probably be
compatible with email applications on other operating systems, such as
Windows and Macintosh.
GnuPG uses public key
cryptography to provide users with a secure exchange of
data. In a public key cryptography scheme, you generate two keys: a
public key and a private key. You exchange your public key with
correspondents or with a keyserver; you should never reveal your
private key.
Encryption depends upon the use of keys. In conventional or symmetric
cryptography, both ends of the transaction have the same key, which they
use to decode each other's transmissions. In public key cryptography,
two keys co-exist: a public key and a private key. A person or an
organization keeps their private key a secret, and publishes their
public key. Data encoded with the public key can only be decoded with
the private key; data encoded with the private key can only be decoded
with the public key.
 | Do Not Reveal Your Private Key |
|---|
| | Remember that your public key can be given to anyone with whom you
want to communicate securely, but you must never give away your
private key.
|
For the most part, cryptography is beyond the scope of this publication;
volumes have been written about the subject. In this chapter, however,
we hope you'll gain enough understanding about
GnuPG to begin using cryptography in your own
correspondence. For more information about
GnuPG, including an online users guide, visit http://www.gnupg.org/. If you
want to learn more about GnuPG, PGP and
encryption technology, see the section called Additional Resources.
 | More Information From the Shell Prompt |
|---|
| | Like most system tools for Red Hat Linux, you'll find documentation on
GnuPG in the man pages and info pages. At a
shell prompt, just type man gpg or info
gpg for a quick reference of GnuPG
commands and options.
|
