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Pretty
Good Privacy (PGP)
What is PGP?
Pretty Good™ Privacy (PGP), from Phil's Pretty Good Software,
is a high security cryptographic software application for MSDOS, Unix,
VAX/VMS, and other computers. PGP allows people to exchange files
or messages with privacy, authentication, and convenience. Privacy
means that only those intended to receive a message can read it. Authentication
means that messages that appear to be from a particular person can only
have originated from that person. Convenience means that privacy
and authentication are provided without the hassles of managing keys
associated with conventional cryptographic software. No secure
channels are needed to exchange keys between users, which makes PGP
much easier to use. This is because PGP is based on a powerful
new technology called public key cryptography.
Using PGP
In order to use PGP, you will first need to create a key set.
- SSH into your account.
- Run the command "pgpk -g". This will prompt you
for the following information:
*Choose the type of your public key.
1. DSS/Diffie-Hellman - New algorithm for 5.0 (default)
2. RSA
Choose 1 or 2: -"Select RSA"-
*Pick your public/private keypair key size.
1. 768 bits- Commercial grade, probably not currently
breakable
2. 1024 bits- High commercial grade, secure for many
years
3. 2048 bits- "Military" grade, secure for
the foreseeable future
Choose 1, 2 or 3, or enter desired number of bits
(768 - 2048): -"A key of 1024 bits is more than
enough, select that".
*Enter a user ID for your public key.
The desired form for this user ID is your FULL name, followed
by your
E-mail address enclosed in <angle brackets>, if you have
an E-mail
For example: Joe Smith <user@domain.com>
If you violate this standard, you will lose much of the benefits
of
PGP 5.0's keyserver and email integration.
Enter a user ID for your public key: -"Fill in the
appropriate info"-
*Enter the validity period of your key in days from 0 - 999.
0 is forever (and the default): -"Enter 0 if you
want this key to last
forever"-
*Choose a pass phrase to protect your private key(s).
Your pass phrase can be any sentence or phrase and may have
many
words, spaces, punctuation, or any other printable characters.
Enter pass phrase: -"Fill in a good passphrase that
you are sure to
remember"-
- Run the command "pgpk -xa userid -o public.key" (userid
refers to the user ID on step 2) This will produce a file called "public.key".
*You can also download pgp from http://www.pgp.com/
and create a keyset on your home computer.
Once this key set is created, you can start encrypting files on from
SSH.
- SSH into your account.
- Run the command "pgp -r userid file -o file.pgp" ("file"
refers to the file you wish to encrypt). This will produce an file"file.pgp"
with the encrypted content of "file".
PGPMail
From your Domain Manager (http://www.yourdomain.com/menu) select PGP
- Copy the contents of the file "public.key" created in
step 3 of the previous section. If you created the key with PGP on
your home computer copy the contents to the appropriate section.
- Click on "Add". (You may not need to run this step if
you created the key from SSH)
- Click on "To test sending a PGPMail".
You need to set up your form to use the 'pgpmail.pl'
The form action line should be
<FORM ACTION="/cgi-sys/pgpmail.pl" METHOD ="POST">
The 'pgpmail.pl' will do all the programming work for you. You alter
the behavior of 'pgpmail.pl' by using hidden fields in your form.
There are three form fields that you must have in your form for PGPMail
to work correctly, recipient, username, and keyname.
Field: recipient
Description: This form field allows you to specify to whom you wish
for your form results to be mailed. Most likely you will want to configure
this option as a hidden form field with a value equal to that of your
e-mail address.
Syntax:
<input type=hidden name="recipient" value="your_username@localnet.com">
Field: username
Description: This form field allows you to specify your username in
the system. This allows PGPMail to look for the configuration files
to encrypt the mail to be sent to you.
Syntax:
<input type=hidden name="username" value="your_username">
Field: keyname
Description: This form field allows you to specify the name of your
public key. This will be the public key that PGPMail uses to encrypt
your mail. You must possess the private key in order to decrypt the
email that is sent.
Syntax:
<input type=hidden name="keyname" value="public_keyname">
cPanel users can set-up PGP via their cPanel Interface.
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