Add paragonie/random_compat to Composer dependencies

vendor/paragonie/random_compat/lib/random_bytes_mcrypt.php

@@ -0,0 +1,77 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 - 2017 Paragon Initiative Enterprises
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+if (!is_callable('random_bytes')) {
+    /**
+     * Powered by ext/mcrypt (and thankfully NOT libmcrypt)
+     *
+     * @ref https://bugs.php.net/bug.php?id=55169
+     * @ref https://github.com/php/php-src/blob/c568ffe5171d942161fc8dda066bce844bdef676/ext/mcrypt/mcrypt.c#L1321-L1386
+     *
+     * @param int $bytes
+     *
+     * @throws Exception
+     *
+     * @return string
+     */
+    function random_bytes($bytes)
+    {
+        try {
+            $bytes = RandomCompat_intval($bytes);
+        } catch (TypeError $ex) {
+            throw new TypeError(
+                'random_bytes(): $bytes must be an integer'
+            );
+        }
+
+        if ($bytes < 1) {
+            throw new Error(
+                'Length must be greater than 0'
+            );
+        }
+
+        $buf = @mcrypt_create_iv($bytes, MCRYPT_DEV_URANDOM);
+        if (
+            $buf !== false
+            &&
+            RandomCompat_strlen($buf) === $bytes
+        ) {
+            /**
+             * Return our random entropy buffer here:
+             */
+            return $buf;
+        }
+
+        /**
+         * If we reach here, PHP has failed us.
+         */
+        throw new Exception(
+            'Could not gather sufficient random data'
+        );
+    }
+}