Add local SAML2-compliant version of the Random ID-generator

Author: tvdijen

README.md

@@ -59,8 +59,8 @@ Example:
     // Create Issuer
     $issuer = new \SimpleSAML\SAML2\XML\saml\Issuer('https://sp.example.edu');
 
-    // Instantiate XML Random utils
-    $randomUtils = new \SimpleSAML\XML\Utils\Random();
+    // Instantiate SAML2 Random utils
+    $randomUtils = new \SimpleSAML\SAML2\Utils\Random();
 
     // Set up an AuthnRequest
     $request = new \SimpleSAML\SAML2\XML\samlp\AuthnRequest(

src/Utils/Random.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\XML\Utils;
+
+use function bin2hex;
+use function random_bytes;
+
+/**
+ * @package simplesamlphp/saml2
+ */
+class Random extends \SimpleSAML\XML\Utils\Random
+{
+    /**
+     * The fixed length of random identifiers.
+     *
+     * This results in the maximum of 160 bits entropy specified in paragraph 1.3.4 of the SAML 2.0 core specifications
+     *
+     * (41 - 1) / 2 = 20 → random_bytes(20) → 160 bits
+     */
+    public const int ID_LENGTH = 41;
+}