Add bootstrap.php checking environment (MB_OVERLOAD_STRING).

composer.json

@@ -66,15 +66,11 @@
     },
     "include-path": ["phpseclib/"],
     "autoload": {
-        "psr-0": {
-            "Crypt": "phpseclib/",
-            "File": "phpseclib/",
-            "Math": "phpseclib/",
-            "Net": "phpseclib/",
-            "System": "phpseclib/"
-        },
         "files": [
-            "phpseclib/Crypt/Random.php"
-        ]
+            "phpseclib/bootstrap.php"
+        ],
+        "psr-4": {
+            "phpseclib\\": "phpseclib/"
+        }
     }
 }

phpseclib/bootstrap.php

@@ -0,0 +1,16 @@
+<?php
+/**
+ * Bootstrapping File for phpseclib
+ *
+ * @license http://www.opensource.org/licenses/mit-license.html MIT License
+ */
+
+if (extension_loaded('mbstring')) {
+    // 2 - MB_OVERLOAD_STRING
+    if (ini_get('mbstring.func_overload') & 2) {
+        throw new \UnexpectedValueException(
+            'Overloading of string functions using mbstring.func_overload ' .
+            'is not supported by phpseclib.'
+        );
+    }
+}