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<!DOCTYPE html>
<html dir="ltr" lang="en">
<head>
<meta charset='utf-8'>
<title>GnuPG</title>
</head>
<body>
<a href="index.html">Tools Index</a>
<h1>GnuPG</h1>
<h2 id="install">1. Install</h2>
<p>Install gnupg;</p>
<pre>
$ sudo prt-get depinst gnupg
</pre>
<p>Create a skeleton configuration to be copied by useradd to
each user home directory;</p>
<pre>
$ sudo mkdir /etc/skel/.gnupg
$ sudo cp /usr/share/gnupg/gpg-conf.skel /etc/skel/.gnupg/gpg.conf
</pre>
<pre>
$ chmod 700 ~/.gnupg
$ chmod -R 600 ~/.gnupg/*
</pre>
<h2 id="genkey">2. Generate keys</h2>
<p>Options for creating a DSA and ElGamal key;</p>
<dl>
<dt>Key Size</dt>
<dd>the defaults are ok.</dd>
<dt>Expiring Date</dt>
<dd>Choose a non-expiring key for your own use. For public
at least choose yearly expiration.</dd>
<dt>Name and Email</dt>
<dd>Real name and e-mail address used to identify your key.</dd>
<dt>Comment</dt>
<dd>Can be empty, make a small comment to help indentify.</dd>
<dt>Passphrase</dt>
<dd>Password should use numebers and special chars.</dd>
</dl>
<p>Generate keys;</p>
<pre>
$ gpg2 --full-gen-key
gpg (GnuPG) 2.1.11; Copyright (C) 2018 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Please select what kind of key you want:
(1) RSA and RSA (default)
(2) DSA and Elgamal
(3) DSA (sign only)
(4) RSA (sign only)
Your selection? 2
DSA keys may be between 1024 and 3072 bits long.
What keysize do you want? (2048) 2048
Requested keysize is 2048 bits
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0) 6m
Key expires at Tue May 30 20:29:36 2017 WEST
Is this correct? (y/N) y
GnuPG needs to construct a user ID to identify your key.
Real name: User Name
Email address: user@core.privat-server.net
Comment: user at external dot org
You selected this USER-ID:
"User Name (user at core) <user@core.privat-server.net>"
Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
</pre>
<p>This will create the follow files;</p>
<pre>
.gnupg/pubring.gpg
.gnupg/random_seed
.gnupg/secring.gpg
.gnupg/trustdb.gp
</pre>
<p>List keys;</p>
<pre>
$ gpg --list-keys
/home/droid/.gnupg/pubring.kbx
------------------------------
pub dsa3072/EE29B7D3 2016-05-30 [SC] [expires: 2017-05-30]
uid [ultimate] User Name (user at core ) <user@core.privat-server.net>
sub elg2112/9BC2DC12 2016-05-30 [E] [expires: 2017-05-30]
</pre>
<p>In this case pub key ID is EE29B7D3, add to .profile;</p>
<pre>
export GPGKEY=0xEE29B7D3
</pre>
<h2 id="keys">3. Key Management</h2>
<p>Key Management;</p>
<pre>
$ gpg --list-keys
$ gpg --list-secret-keys
$ gpg --fingerprint
$ gpg --delete-key UID
$ gpg --delete-secret-key
$ gpg --edit-key UID
</pre>
<h3>3.1. Edit key</h3>
<pre>
$ gpg --edit-key KEYID
adduid
</pre>
<h3>3.2. Revoke key</h3>
<p>Follow the instructions and then select the user you
want to revoque, where N is the UID of the user;</p>
<pre>
$ gpg --edit-key KEYID
uid N
revuid
save
</pre>
<h2 id="keyex">4. Export and import keys</h2>
<h3>4.1. Export Key</h3>
<p>Public keys can be exported in binary format
or ASCII-armored format. To export binary format;</p>
<pre>
$ gpg --list-keys
</pre>
<pre>
$ gpg --output user.gpg --export user@localhost
</pre>
<p>Generate an ASCII version of your public key;</p>
<pre>
$ gpg --armor --output user.asc --export 'User Name'
</pre>
<h3>4.2. Export to keyserver</h3>
<p>The primary public key's ID is referenced in the pub
line after the key size, for example the key created above,
the short key ID is EE29B7D3:
<pre>
gpg --keyserver search.keyserver.net --send-key EE29B7D3
</pre>
<h3>4.3. Import Key</h3>
<p>Is very easy to import public keys;</p>
<pre>
$ gpg --import user.gpg
</pre>
<p>To list imported keys;</p>
<pre>
$ gpg --list-keys
</pre>
<h3>4.4. Key Servers</h3>
<p>Configure GnuPG to automatically fetch public keys,
uncomment following line to ~/.gnupg/gpg.conf;</p>
<pre>
keyserver-options auto-key-retrieve
</pre>
<p>And add a server, in this example wwwkeys.pgp.net;</p>
<pre>
keyserver wwwkeys.pgp.net
keyserver search.keyserver.net
keyserver pgp.mit.edu
</pre>
<p>Test your configuration as described by Justin R. Miller <a href="http://codesorcery.net/old/mutt/mutt-gnupg-howto">Mutt Gnupg Howto</a>;</p>
<pre>
$ gpg --recv-keys 0xC9C40C31
</pre>
<p>Confirm;</p>
<pre>
gpg --list-keys justin
</pre>
<h2 id="cryptsign">5. Encrypt, decrypt and signing</h2>
<h3>5.1. Encrypt file</h3>
<p>To be abble to decrypt the document we need to include
public key in the recipient list;</p>
<pre>
$ gpg --output index.html.gpg --encrypt \
--recipient user@localhost \
--recipient bob@localhost \
index.html
</pre>
<h3>5.2. Decrypt file</h3>
<p>To decrypt the file;</p>
<pre>
$ gpg --output index.html --decrypt index.html.gpg
</pre>
<h3>5.3. Signing a File</h3>
<p>A digital signature certifies and timestamps a document.
If the document is subsequently modified in any way,
a verification of the signature will fail. A digital
signature can serve the same purpose as a hand-written
signature with the additional benefit of being
tamper-resistant. Example on how to sign a file;</p>
<p>To send document uncompressed and wrapped in an ASCII-armored
signature;</p>
<pre>
$ gpg --clearsign index.html
</pre>
<p>Verify signature;</p>
<pre>
$ gpg --verify index.html.asc
</pre>
<p>To encrypt and sign a file;</p>
<pre>
$ gpg --output index.html.gpg --sign --encrypt \
--recipient bob@localhost \
index.html
</pre>
<p>To decrypt;</p>
<pre>
$ gpg --output index.html --decrypt index.html.gpg
</pre>
<p>You should see this message on the output;</p>
<pre>
gpg: Good signature from "User (user at localhost) <user@localhost>"
</pre>
<p>Detached signatures create a separate file for
signature;</p>
<pre>
$ gpg --output index.html.sig --detach-sig index.html
</pre>
<p>Now you can send index.html.sig and on the other end;</p>
<pre>
$ gpg --verify index.html.sig
</pre>
<a href="index.html">Tools Index</a>
<p>
This is part of the Hive System Documentation.
Copyright (C) 2018
Hive Team.
See the file <a href="../fdl-1.3-standalone.html">Gnu Free Documentation License</a> for copying conditions.</p>
</body>
</html>
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