+USE_GPG
+ When set to "yes", Brioche will encrypt the archives with GnuPG.
+ See the `Encryption with GnuPG`_ section below for a detailed explanation on
+ how to use GnuPG with Brioche.
+
+GPG_KEY
+ The identifier of the public GnuPG key to use when encrypting the archives.
+ This is the key that will be needed in case of restore.
+
+GPG_PASSPHRASE
+ The passphrase for the GnuPG private key used to encrypt the archives.
+