bug #470, use a dedicated lib to generate random bytes

1 files changed, 81 insertions, 0 deletions

diff --git a/include/random_compat/random_bytes_com_dotnet.php b/include/random_compat/random_bytes_com_dotnet.php
new file mode 100644
index 000000000..342282549
--- /dev/null
+++ b/include/random_compat/random_bytes_com_dotnet.php
@@ -0,0 +1,81 @@
+<?php
+/**
+ * Random_* Compatibility Library 
+ * for using the new PHP 7 random_* API in PHP 5 projects
+ * 
+ * The MIT License (MIT)
+ * 
+ * Copyright (c) 2015 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.
+ */
+
+/**
+ * Windows with PHP < 5.3.0 will not have the function
+ * openssl_random_pseudo_bytes() available, so let's use
+ * CAPICOM to work around this deficiency.
+ * 
+ * @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 = '';
+    $util = new COM('CAPICOM.Utilities.1');
+    $execCount = 0;
+
+    /**
+     * Let's not let it loop forever. If we run N times and fail to
+     * get N bytes of random data, then CAPICOM has failed us.
+     */
+    do {
+        $buf .= base64_decode($util->GetRandom($bytes, 0));
+        if (RandomCompat_strlen($buf) >= $bytes) {
+            /**
+             * Return our random entropy buffer here:
+             */
+            return RandomCompat_substr($buf, 0, $bytes);
+        }
+        ++$execCount; 
+    } while ($execCount < $bytes);
+
+    /**
+     * If we reach here, PHP has failed us.
+     */
+    throw new Exception(
+        'Could not gather sufficient random data'
+    );
+}