doc/GnuPG-signature.html

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  77 <h1 id="gnupg-signature">GnuPG signature</h1>
  78 <h2 id="introduction">Introduction</h2>
  79 <h3 id="pgp-and-gpg">PGP and GPG</h3>
  80 <p><a href="https://gnupg.org/">Gnu Privacy Guard</a> (GnuPG) is an Open Source implementation of the <a href="https://en.wikipedia.org/wiki/Pretty_Good_Privacy#OpenPGP">Pretty Good [](.html)<br />Privacy</a> (OpenPGP) specification. Its main purposes are digital authentication,<br />signature and encryption.</p>
  81 <p>It is often used by the <a href="https://en.wikipedia.org/wiki/Free_and_open-source_software">FLOSS</a> community to verify:<a href=".html"></a></p>
  82 <ul>
  83 <li>Linux package signatures: Debian <a href="https://wiki.debian.org/SecureApt">SecureApt</a>, ArchLinux <a href="https://www.archlinux.org/master-keys/">Master [](.html)<br />Keys</a></li>
  84 <li><a href="https://en.wikipedia.org/wiki/Revision_control">SCM</a> releases &amp; maintainer identity<a href=".html"></a></li>
  85 </ul>
  86 <h3 id="trust">Trust</h3>
  87 <p>To quote Phil Pennock (the author of the <a href="https://bitbucket.org/skskeyserver/sks-keyserver/wiki/Home">SKS</a> key server - <a href="http://sks.spodhuis.org/" class="uri">http://sks.spodhuis.org/</a>):<a href=".html"></a></p>
  88 <blockquote>
  89 <p>You MUST understand that presence of data in the keyserver (pools) in no way connotes trust. Anyone can generate a key, with any name or email address, and upload it. All security and trust comes from evaluating security at the “object level”, via PGP Web-Of-Trust signatures. This keyserver makes it possible to retrieve keys, looking them up via various indices, but the collection of keys in this public pool is KNOWN to contain malicious and fraudulent keys. It is the common expectation of server operators that users understand this and use software which, like all known common OpenPGP implementations, evaluates trust accordingly. This expectation is so common that it is not normally explicitly stated.</p>
  90 </blockquote>
  91 <p>Trust can be gained by having your key signed by other people (and signing their key back, too :) ), for instance during <a href="https://en.wikipedia.org/wiki/Key_signing_party">key signing parties</a>, see:<a href=".html"></a></p>
  92 <ul>
  93 <li><a href="http://www.cryptnet.net/fdp/crypto/keysigning_party/en/keysigning_party.html">The Keysigning party HOWTO</a><a href=".html"></a></li>
  94 <li><a href="https://en.wikipedia.org/wiki/Web_of_trust">Web of trust</a><a href=".html"></a></li>
  95 </ul>
  96 <h2 id="generate-a-gpg-key">Generate a GPG key</h2>
  97 <p>See <a href="http://stackoverflow.com/a/16725717">Generating a GPG key for Git tagging</a>.<a href=".html"></a></p>
  98 <h3 id="gpg---provide-identity-information">gpg - provide identity information</h3>
  99 <pre class="sourceCode bash"><code class="sourceCode bash">$ <span class="kw">gpg</span> --gen-key
 100
 101 <span class="kw">gpg</span> (GnuPG) <span class="kw">2.1.6;</span> <span class="kw">Copyright</span> (C) <span class="kw">2015</span> Free Software Foundation, Inc.
 102 <span class="kw">This</span> is free software: you are free to change and redistribute it.
 103 <span class="kw">There</span> is NO WARRANTY, to the extent permitted by law.
 104
 105 <span class="kw">Note</span>: Use <span class="st">&quot;gpg2 --full-gen-key&quot;</span> for a full featured key generation dialog.
 106
 107 <span class="kw">GnuPG</span> needs to construct a user ID to identify your key.
 108
 109 <span class="kw">Real</span> name: Marvin the Paranoid Android
 110 <span class="kw">Email</span> address: marvin@h2g2.net
 111 <span class="kw">You</span> selected this USER-ID:
 112     <span class="st">&quot;Marvin the Paranoid Android &lt;marvin@h2g2.net&gt;&quot;</span>
 113
 114 <span class="kw">Change</span> (N)<span class="kw">ame</span>, (E)<span class="kw">mail</span>, or (O)<span class="kw">kay</span>/<span class="kw">(Q)uit?</span> o
 115 <span class="kw">We</span> need to generate a lot of random bytes. It is a good idea to perform
 116 <span class="kw">some</span> other action (type on the keyboard, move the mouse, utilize the
 117 <span class="kw">disks</span>) <span class="kw">during</span> the prime generation<span class="kw">;</span> <span class="kw">this</span> gives the random number
 118 <span class="kw">generator</span> a better chance to gain enough entropy.</code></pre>
 119 <h3 id="gpg---entropy-interlude">gpg - entropy interlude</h3>
 120 <p>At this point, you will:</p>
 121 <ul>
 122 <li>be prompted for a secure password to protect your key (the input method will depend on your Desktop Environment and configuration)</li>
 123 <li>be asked to use your machine's input devices (mouse, keyboard, etc.) to generate random entropy; this step <em>may take some time</em></li>
 124 </ul>
 125 <h3 id="gpg---key-creation-confirmation">gpg - key creation confirmation</h3>
 126 <pre class="sourceCode bash"><code class="sourceCode bash"><span class="kw">gpg</span>: key A9D53A3E marked as ultimately trusted
 127 <span class="kw">public</span> and secret key created and signed.
 128
 129 <span class="kw">gpg</span>: checking the trustdb
 130 <span class="kw">gpg</span>: 3 marginal(s) <span class="kw">needed</span>, 1 complete(s) <span class="kw">needed</span>, PGP trust model
 131 <span class="kw">gpg</span>: depth: 0  valid:   2  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 2u
 132 <span class="kw">pub</span>   rsa2048/A9D53A3E 2015-07-31
 133       <span class="kw">Key</span> fingerprint = AF2A 5381 E54B 2FD2 14C4  A9A3 0E35 ACA4 A9D5 3A3E
 134 <span class="kw">uid</span>       [ultimate] Marvin the Paranoid Android <span class="kw">&lt;</span>marvin@h2g2.net<span class="kw">&gt;</span>[](.html)
 135 <span class="kw">sub</span>   rsa2048/8C0EACF1 2015-07-31</code></pre>
 136 <h3 id="gpg---submit-your-public-key-to-a-pgp-server-optional">gpg - submit your public key to a PGP server (Optional)</h3>
 137 <pre class="sourceCode bash"><code class="sourceCode bash">$ <span class="kw">gpg</span> --keyserver pgp.mit.edu --send-keys A9D53A3E
 138 <span class="kw">gpg</span>: sending key A9D53A3E to hkp server pgp.mit.edu</code></pre>
 139 <h2 id="create-and-push-a-gpg-signed-tag">Create and push a GPG-signed tag</h2>
 140 <p>See <a href="http://git-scm.com/book/en/v2/Distributed-Git-Maintaining-a-Project#Tagging-Your-Releases">Git - Maintaining a project - Tagging your [](.html)<br />releases</a>.</p>
 141 <h3 id="prerequisites">Prerequisites</h3>
 142 <p>This guide assumes that you have:</p>
 143 <ul>
 144 <li>a GPG key matching your GitHub authentication credentials
 145 <ul>
 146 <li>i.e., the email address identified by the GPG key is the same as the one in your <code>~/.gitconfig</code></li>
 147 </ul></li>
 148 <li>a GitHub fork of Shaarli</li>
 149 <li>a local clone of your Shaarli fork, with the following remotes:
 150 <ul>
 151 <li><code>origin</code> pointing to your GitHub fork</li>
 152 <li><code>upstream</code> pointing to the main Shaarli repository</li>
 153 </ul></li>
 154 <li>maintainer permissions on the main Shaarli repository (to push the signed tag)</li>
 155 </ul>
 156 <h3 id="bump-shaarlis-version">Bump Shaarli's version</h3>
 157 <pre class="sourceCode bash"><code class="sourceCode bash">$ <span class="kw">cd</span> /path/to/shaarli
 158
 159 <span class="co"># create a new branch</span>
 160 $ <span class="kw">git</span> fetch upstream
 161 $ <span class="kw">git</span> checkout upstream/master -b v0.5.0
 162
 163 <span class="co"># bump the version number</span>
 164 $ <span class="kw">vim</span> index.php shaarli_version.php
 165
 166 <span class="co"># commit the changes</span>
 167 $ <span class="kw">git</span> add index.php shaarli_version.php
 168 $ <span class="kw">git</span> commit -s -m <span class="st">&quot;Bump version to v0.5.0&quot;</span>
 169
 170 <span class="co"># push the commit on your GitHub fork</span>
 171 $ <span class="kw">git</span> push origin v0.5.0</code></pre>
 172 <h3 id="create-and-merge-a-pull-request">Create and merge a Pull Request</h3>
 173 <p>This one is pretty straightforward ;-)</p>
 174 <h3 id="create-and-push-a-signed-tag">Create and push a signed tag</h3>
 175 <pre class="sourceCode bash"><code class="sourceCode bash"><span class="co"># update your local copy</span>
 176 $ <span class="kw">git</span> checkout master
 177 $ <span class="kw">git</span> fetch upstream
 178 $ <span class="kw">git</span> pull upstream master
 179
 180 <span class="co"># create a signed tag</span>
 181 $ <span class="kw">git</span> tag -s -m <span class="st">&quot;Release v0.5.0&quot;</span> v0.5.0
 182
 183 <span class="co"># push it to &quot;upstream&quot;</span>
 184 $ <span class="kw">git</span> push --tags upstream</code></pre>
 185 <h3 id="verify-a-signed-tag">Verify a signed tag</h3>
 186 <p><a href="https://github.com/shaarli/Shaarli/releases/tag/v0.5.0"><code>v0.5.0</code></a> is the first GPG-signed tag pushed on the Community Shaarli.<a href=".html"></a></p>
 187 <p>Let's have a look at its signature!</p>
 188 <pre class="sourceCode bash"><code class="sourceCode bash">$ <span class="kw">cd</span> /path/to/shaarli
 189 $ <span class="kw">git</span> fetch upstream
 190
 191 <span class="co"># get the SHA1 reference of the tag</span>
 192 $ <span class="kw">git</span> show-ref tags/v0.5.0
 193 <span class="kw">f7762cf803f03f5caf4b8078359a63783d0090c1</span> refs/tags/v0.5.0
 194
 195 <span class="co"># verify the tag signature information</span>
 196 $ <span class="kw">git</span> verify-tag f7762cf803f03f5caf4b8078359a63783d0090c1
 197 <span class="kw">gpg</span>: Signature made Thu 30 Jul 2015 11:46:34 CEST using RSA key ID 4100DF6F
 198 <span class="kw">gpg</span>: Good signature from <span class="st">&quot;VirtualTam &lt;virtualtam@flibidi.net&gt;&quot;</span> [ultimate][](.html)</code></pre>
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