ZeroBin 0.17

* added deletion link.
* small refactoring.
* improved regex checks.
* larger server alt on installation.

lib/serversalt.php

@@ -0,0 +1,71 @@
+<?php
+/**
+ * ZeroBin
+ *
+ * a zero-knowledge paste bin
+ *
+ * @link      http://sebsauvage.net/wiki/doku.php?id=php:zerobin
+ * @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
+ * @license   http://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
+ * @version   0.17
+ */
+
+/**
+ * serversalt
+ *
+ * This is a random string which is unique to each ZeroBin installation.
+ * It is automatically created if not present.
+ *
+ * Salt is used:
+ * - to generate unique VizHash in discussions (which are not reproductible across ZeroBin servers)
+ * - to generate unique deletion token (which are not re-usable across ZeroBin servers)
+ */
+class serversalt extends persistence
+{
+    /**
+     * @access private
+     * @static
+     * @var    string
+     */
+    private static $_salt = '';
+
+    /**
+     * generate a large random hexadecimal salt
+     *
+     * @access public
+     * @static
+     * @return string
+     */
+    public static function generate()
+    {
+        $randomSalt = '';
+        for($i=0; $i<16; ++$i) {
+            $randomSalt .= base_convert(mt_rand(), 10, 16);
+        }
+        self::$_salt = $randomSalt;
+        return self::$_salt;
+    }
+
+    /**
+     * get server salt
+     *
+     * @access public
+     * @static
+     * @return string
+     */
+    public static function get()
+    {
+    	if (strlen(self::$_salt)) return self::$_salt;
+
+        $file = 'salt.php';
+        if (!self::_exists($file)) {
+            self::_store(
+            	$file,
+                '<?php /* |'. self::generate() . '| */ ?>'
+            );
+        }
+        $items = explode('|', file_get_contents(self::getPath($file)));
+        self::$_salt = $items[1];
+        return $items[1];
+    }
+}