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  <sect1 id="encryption-intro">
    <title>What is Encryption?</title>
    <para>
      Encryption is an ancient method of changing readable text to unreadable
      text that dates back to Egyptian times.  Encryption takes the statement
      "Evolution" and turns it into something which cannot be read without help
      through decryption.
      <example>
	<title>Encryption Example</title>
	<para>
	  Kevin orders an <application>Evolution</application> t-shirt from
	  Ximian, Inc. over the internet.  He puts in his credit card number
	  which is 1234-567-8901.  For security, his computer encrypts the
	  credit card number so it can be safely transmitted over the internet.
	  The number now is @#$23ui7yr87#@!48970fsd, which holds no intentional
	  resemblance to the inital number.  When the information gets to
	  Ximian, Inc. it'll be decrypted into the inital number.
	</para>
      </example>
      Encryption can be used in email in two ways: to verify that the sender is
      the real sender, and to hide the message while in transmission.
      <application>Evolution</application> has the capability to do both.  
    </para>
  </sect1>
  <sect1 id="generating-key">
    <title>Generating your PGP key</title>
    <para>
      First, you need to create a PGP key.  To do this, you'll need GPG
      installed.
    </para>
    <tip>
      <title>GPG Versions</title>
      <para>
	This manual covers version 1.0.6 of GPG.  If your version is different,
	this may not be entirely accurate.  You may find out your version number
	by typing in: <command>gpg --version</command>.
	</para>
      </tip>
    <para>
      You can start by typing in: <command>gpg --gen-key</command>.  At the
      first question, select 1.  The next question asks you about key length.
      The longer the key, more stronger it is.  However, the longer the key, the
      longer it takes to generate.  This is your choice.  However, 1024 bits
      (default) should be adequate.  The next question asks you if you want your
      key to expire.  Expiring keys make your key invalid after a certain amount
      of time, so old keys don't float around active.  This is the same concept
      as a coupon at a supermarket.  Next, you'll type in your Real name, your
      email address, and a comment.  You should not forge this information, as
      it is used later to verify who you are.  Assuming that all your
      information is correct, press "O" to continue.  GPG now asks you for a
      passphrase.  This is a password which you will need to decrypt and encrypt
      messages.  This can be any length, with any characters in it.  It is case
      sensitive, which means that it does know the difference between capital
      letters and lower-case.  Now your key is generated.  It is recommend you
      surf the internet, read your email, or write a letter in a word
      processor.  This help creates randomness in the key.
    </para>
    <para>
      Once this is completed, you'll be dropped back to the command line.
      Now you can view your key information by typing <command>gpg
      --list-keys</command>.  You should see something similar to this:
      <example id="gpg-list-keys">
	<title>GPG Listing Keys</title>
	<para>
	  /home/bob/.gnupg/pubring.gpg
	  ----------------------------
	  pub 1024D/32j38dk2 2001-06-20 bob &lt;bob@bob.com&gt;
	  sub 1024g/289sklj3 2001-06-20 [expires: 2002-11-14]
	</para>
      </example>
      You'll now need to upload your public key to a keyserver, so that your
      friends can use your key.  You'll need to know the ID of your key, which
      is after the 1024D on the line beginning with pub.  For this example, it
      is 32j38dk2.  You now type in <command>gpg --send-keys --keyserver
      wwwkeys.pgp.net 32j38dk2</command>.  Substitute your key ID for 32j38dk2.
      You will be prompted to type in your password <!-- verify that you need to
      enter your password here --> and your key will be uploaded for your
      friends to download.
    </para>
  </sect1>
  <sect1 id="encrypt-evo-integ">
    <title>Setting up Evolution's Encryption</title>
    <para>
      You'll need to open
      <menuchoice>
	<guimenu>Tools</guimenu>
	<guimenuitem>Mail Settings</guimenuitem>
      </menuchoice>
     Once there, select the account you'd like to associate the key to and click
     the <guibutton>Edit</guibutton> button.  In the
     <guilabel>Security</guilabel> tab is a section labeled <guilabel>Pretty
     Goog Privacy</guilabel>.  Enter your key ID and click
     <guibutton>OK</guibutton>.  Your key is now integrated into your identity
     in <application>Evolution</application>.
    </para>
  </sect1>
  <sect1 id="encrypt-sending">
    <title>Sending Encrypted Messages</title>
    <para>
      You can either sign or encrypt a message.  When you sign a message, verify
      that you were the one who sent it, and that no one is forging your
      identity.  Encrypting a message makes it impossible for someone with
      prying eyes to view it while it's in tranmission.
    </para>
    <para>
      <sect2 id="sign-msg">
	<title>Signing a Message</title>
	<para>
	  To sign a message, you simply click
	  <menuchoice>
	    <guimenu>Security</guimenu>
	    <guimenuitem>PGP Sign</guimenuitem>
	  </menuchoice>
	  .  You will be prompted for your PGP password.  Once you enter it,
	  click <guibutton>OK</guibutton> and your message will be signed.
	</para>
      </sect2>
      <sect2 id="encrypt-msg">
	<title>Encrypting a Message</title>
	<para>
	  Encrypting a message is very similar to signing a message.  You simply
	  click the menu item 
	  <menuchoice>
	    <guimenu>Security</guimenu>
	    <guimenuitem>PGP Encrypt</guimenuitem>
	  </menuchoice>
	</para>
      </sect2>
    </para>
  </sect1>
  <sect1 id="unencrypting">
    <title>Unencrypting a Recieved Message</title>
    <para>
      Sometimes, a friend will send you a message which is encrypted.  In order
      for you to read it, you need to unencrypt it.
    </para>
    <para>
      When you view the encrypted message, <application>Evolution</application>
      will prompt you for your PGP password.  You type in your PGP password and
      the message is then decrypted.
    </para>
  </sect1>
  </article>
