--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/bin/decrypt.sh	Thu Jan 04 15:50:29 2018 -0500
@@ -0,0 +1,67 @@
+#!/usr/bin/env php
+<?php
+/*
+ +-----------------------------------------------------------------------+
+ | bin/decrypt.sh                                                        |
+ |                                                                       |
+ | This file is part of the Roundcube Webmail client                     |
+ | Copyright (C) 2005-2009, The Roundcube Dev Team                       |
+ |                                                                       |
+ | Licensed under the GNU General Public License version 3 or            |
+ | any later version with exceptions for skins & plugins.                |
+ | See the README file for a full license statement.                     |
+ |                                                                       |
+ | PURPOSE:                                                              |
+ |   Decrypt the encrypted parts of the HTTP Received: headers           |
+ |                                                                       |
+ +-----------------------------------------------------------------------+
+ | Author: Tomas Tevesz <ice@extreme.hu>                                 |
+ +-----------------------------------------------------------------------+
+*/
+
+/**
+ * If http_received_header_encrypt is configured, the IP address and the
+ * host name of the added Received: header is encrypted with 3DES, to
+ * protect information that some could consider sensitve, yet their
+ * availability is a must in some circumstances.
+ *
+ * Such an encrypted Received: header might look like:
+ *
+ * Received: from DzgkvJBO5+bw+oje5JACeNIa/uSI4mRw2cy5YoPBba73eyBmjtyHnQ==
+ *  [my0nUbjZXKtl7KVBZcsvWOxxtyVFxza4]
+ *  with HTTP/1.1 (POST); Thu, 14 May 2009 19:17:28 +0200
+ *
+ * In this example, the two encrypted components are the sender host name
+ * (DzgkvJBO5+bw+oje5JACeNIa/uSI4mRw2cy5YoPBba73eyBmjtyHnQ==) and the IP
+ * address (my0nUbjZXKtl7KVBZcsvWOxxtyVFxza4).
+ *
+ * Using this tool, they can be decrypted into plain text:
+ *
+ * $ bin/decrypt.sh 'my0nUbjZXKtl7KVBZcsvWOxxtyVFxza4' \
+ * > 'DzgkvJBO5+bw+oje5JACeNIa/uSI4mRw2cy5YoPBba73eyBmjtyHnQ=='
+ * 84.3.187.208
+ * 5403BBD0.catv.pool.telekom.hu
+ * $
+ *
+ * Thus it is known that this particular message was sent by 84.3.187.208,
+ * having, at the time of sending, the name of 5403BBD0.catv.pool.telekom.hu.
+ *
+ * If (most likely binary) junk is shown, then
+ *  - either the encryption password has, between the time the mail was sent
+ *    and 'now', changed, or
+ *  - you are dealing with counterfeit header data.
+ */
+
+define('INSTALL_PATH', realpath(__DIR__ .'/..') . '/');
+
+require INSTALL_PATH . 'program/include/clisetup.php';
+
+if ($argc < 2) {
+	die("Usage: " . basename($argv[0]) . " encrypted-hdr-part [encrypted-hdr-part ...]\n");
+}
+
+$RCMAIL = rcube::get_instance();
+
+for ($i = 1; $i < $argc; $i++) {
+	printf("%s\n", $RCMAIL->decrypt($argv[$i]));
+};