Document the certificate handling

- Show the various options
- Optimize the documentation images

doc/en/index.txt

@@ -9,6 +9,7 @@ Available pages
 
 * link:install.html[Installation]
 * link:configure.html[Configuration]
+* link:ssl.html[SSL Management]
 * link:usage.html[Usage]
 * link:themes.html[Theming]
 * link:keys.html[Keys]

doc/en/ssl.txt

@@ -0,0 +1,62 @@
+SSL Management
+==============
+
+Starting from version 0.7.5, poezio offers some options to check the validity
+of a X.509 certificate.
+
+TOFU
+----
+
+The default handling method is the
+link:https://en.wikipedia.org/wiki/User:Dotdotike/Trust_Upon_First_Use[TOFU/TUFU]
+method. At your first connection, poezio will save the hash of the certificate
+received, and will compare the received one and the first one for the next
+connections.
+
+
+If you are paranoid (or run poezio for the first time in an unsafe
+environment), you can set the _certificate_ value of your config file yourself
+(the hash, not colon-separated).
+
+
+If the certificate is not the same, poezio will show an error message and wait
+for confirmation:
+
+image:../images/ssl_warning.png["Warning message", title="Warning message"]
+
+If you press y, the change is validated an poezio will match the next certs
+with the accepted one.
+
+If you press n, you will get the confirmation that the change has been
+refused, and you will be disconnected.
+
+CA-Based
+--------
+
+If you are connecting to a large server that has several front-facing
+endpoints, you might be bothered by having to validate the change each time,
+and you may want to check only if it the same authority delivered the
+certificate.
+
+You can then set the _ca_cert_path_ option to the path of a file containing
+the validation chain in link:https://tools.ietf.org/html/rfc1422.html[PEM
+format] ; those certificates are usually in /usr/share/ca-certificates/ but it
+may vary depending of your distribution.
+
+If the authority does not match when connecting, you should be disconnected.
+
+None
+----
+
+If you do not want to bother with certificate validation at all (which can be
+the case when you run poezio on the same computer as your jabber server), you
+can set the _ignore_certificate_ value to true, and let the _ca_cert_path_
+option empty (or even remove it).
+
+
+
+
+
+
+
+