From dc998ef791677a63e4f8e5cbe71aed51c2fc452f Mon Sep 17 00:00:00 2001
From: Patrick Spek <p.spek@tyil.nl>
Date: Sat, 30 May 2020 21:51:06 +0200
Subject: Add a new post on settting up PGP WKD

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 _posts/2020-05-30-setting-up-pgp-wkd.md | 105 ++++++++++++++++++++++++++++++++
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+---
+title: Setting Up a PGP Webkey Directory
+layout: post
+tags: Git Cgit Gentoo
+social: {}
+description: >
+  A friend on IRC asked me how I made my PGP key available in a webkey
+  directory. This post will detail my path, so you can easily set it up for
+  yourself.
+---
+
+A little while ago, a friend on IRC asked me how I set up a PGP webkey
+directory on my website. For those that don't know, a webkey directory is a
+method to find keys through `gpg`'s `--locate-key` command. This allows people
+to find my key using this command:
+
+{% highlight sh %}
+gpg --locate-key p.spek@tyil.nl
+{% endhighlight %}
+
+This is a very user-friendly way for people to get your key, as compared to
+using long IDs.
+
+This post will walk you through setting it up on your site, so you can make
+your key more easily accessible to other people.
+
+## Set up the infrastructure
+
+For a webkey directory to work, you simply need to have your key available at a
+certain path on your website. The base path for this is
+`.well-known/openpgpkey/`.
+
+{% highlight sh %}
+mkdir -p .well-known/openpgpkey
+{% endhighlight %}
+
+The webkey protocol will check for a `policy` file to exist, so you must create
+this too. The file can be completely empty, and that's exactly how I have it.
+
+{% highlight sh %}
+touch .well-known/openpgpkey/policy
+{% endhighlight %}
+
+The key(s) will be placed in the `hu` directory, so create this one too.
+
+{% highlight sh %}
+mkdir .well-known/openpgpkey/hu
+{% endhighlight %}
+
+## Adding your PGP key
+
+The key itself is just a standard export of your key, without ASCII armouring.
+However, the key does need to have its file **name** in a specific format.
+Luckily, you can just show this format with `gpg`'s `--with-wkd-hash` option.
+
+{% highlight sh %}
+gpg --with-wkd-hash -k p.spek@tyil.nl
+{% endhighlight %}
+
+This will yield output that may look something like this:
+
+{% highlight text %}
+pub   rsa4096/0x7A6AC285E2D98827 2018-09-04 [SC]
+      Key fingerprint = 1660 F6A2 DFA7 5347 322A  4DC0 7A6A C285 E2D9 8827
+uid                   [ultimate] Patrick Spek <p.spek@tyil.nl>
+                      i4fxxwcfae1o4d7wnb5bop89yfx399yf@tyil.nl
+sub   rsa2048/0x031D65902E840821 2018-09-04 [S]
+sub   rsa2048/0x556812D46DABE60E 2018-09-04 [E]
+sub   rsa2048/0x66CFE18D6D588BBF 2018-09-04 [A]
+{% endhighlight %}
+
+What we're interested in is the `uid` line with the hash in the local-part of
+the email address, which would be `i4fxxwcfae1o4d7wnb5bop89yfx399yf@tyil.nl`.
+For the filename, we only care about the local-part itself, meaning the export
+of the key must be saved in a file called `i4fxxwcfae1o4d7wnb5bop89yfx399yf`.
+
+{% highlight sh %}
+gpg --export 0x7A6AC285E2D98827 > .well-known/openpgpkey/hu/i4fxxwcfae1o4d7wnb5bop89yfx399yf
+{% endhighlight %}
+
+## Configuring your webserver
+
+Lastly, your webserver may require some configuration to serve the files
+correctly. For my blog, I'm using [`lighttpd`](https://www.lighttpd.net/), for
+which the configuration block I'm using is as follows.
+
+{% highlight lighttpd %}
+$HTTP["url"] =~ "^/.well-known/openpgpkey" {
+	setenv.add-response-header = (
+		"Access-Control-Allow-Origin" => "*",
+	)
+}
+{% endhighlight %}
+
+It may be worthwhile to note that if you do any redirection on your domain,
+such as adding `www.` in front of it, the key lookup may fail. The error
+message given by `gpg` on WKD lookup failures is... poor to say the least, so
+if anything goes wrong, try some verbose `curl` commands and ensure that the
+key is accessible at the right path in a single HTTP request.
+
+## Wrapping up
+
+That's all there's to it! Adding this to your site should be relatively
+straightforward, but it may be a huge convenience to anyone looking for your
+key. If you have any questions or feedback, feel free to reach out to me!
-- 
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