[securemail] Update Composer dependencies

- Update phpseclib/phpseclib to version 2.0.4
- Update singpolyma/openpgp-php to version 0.3.0

securemail/vendor/singpolyma/openpgp-php/examples/clearsign.php

@@ -0,0 +1,31 @@
+<?php
+
+require_once dirname(__FILE__).'/../lib/openpgp.php';
+require_once dirname(__FILE__).'/../lib/openpgp_crypt_rsa.php';
+
+/* Parse secret key from STDIN, the key must not be password protected */
+$wkey = OpenPGP_Message::parse(file_get_contents('php://stdin'));
+$wkey = $wkey[0];
+
+$string = "This\nis\na\ntest.";
+
+/* Create a new literal data packet */
+$data = new OpenPGP_LiteralDataPacket($string, array('format' => 'u', 'filename' => 'stuff.txt'));
+$data->normalize(true); // Clearsign-style normalization of the LiteralDataPacket
+
+/* Create a signer from the key */
+$sign = new OpenPGP_Crypt_RSA($wkey);
+
+/* The message is the signed data packet */
+$m = $sign->sign($data);
+
+/* Generate clearsigned data */
+$packets = $m->signatures()[0];
+echo "-----BEGIN PGP SIGNED MESSAGE-----\nHash: SHA256\n\n";
+// Output normalised data.  You could convert line endings here
+// without breaking the signature, but do not add any
+// trailing whitespace to lines.
+echo preg_replace("/^-/", "- -",  $packets[0]->data)."\n";
+echo OpenPGP::enarmor($packets[1][0]->to_bytes(), "PGP SIGNATURE");
+
+?>