Add generic PHP code for decryption/parsing

In general, you're better off looking at the mediawiki plugin which
is a bit more complete..

diff --git a/tools/communityauth/sample/php/generic_php.php b/tools/communityauth/sample/php/generic_php.php
new file mode 100755 (executable)
index 0000000..3ceb373
--- /dev/null
+++ b/tools/communityauth/sample/php/generic_php.php
@@ -0,0 +1,33 @@
+#!/usr/bin/env php
+<?php
+if ($argc != 4) {
+  print "Usage: generic_php.php <iv> <data>\n\n";
+  exit(1);
+}
+
+$key = $argv[1];
+$iv = $argv[2];
+$d = $argv[3];
+
+$key = base64_decode(strtr($key, '-_', '+/'), true);
+$iv = base64_decode(strtr($iv, '-_', '+/'), true);
+$d = base64_decode(strtr($d, '-_', '+/'), true);
+
+$td = mcrypt_module_open("rijndael-128", "", "cbc", "");
+mcrypt_generic_init($td, $key, $iv);
+$decrypted = mdecrypt_generic($td, $d);
+mcrypt_generic_deinit($td);
+mcrypt_module_close($td);
+
+parse_str($decrypted, $data);
+
+if ($data['t'] < time() - 10) {
+  print  "*** Authentication timestamp too old ***\n";
+}
+
+print "User: " . $data['u'] . "\n";
+print "Email: " . $data['e'] . "\n";
+print "First: " . $data['f'] . "\n";
+print "Last: " . $data['l'] . "\n";
+print "\n";
+?>
\ No newline at end of file