PHP 8.1 Compatibility

Fix Serializable  PHP 8.1 Compatibility Issue

src/Binary/ByteBuffer.php

@@ -211,7 +211,7 @@ class ByteBuffer implements \JsonSerializable, \Serializable {
     /**
      * jsonSerialize interface
      * return binary data in RFC 1342-Like serialized string
-     * @return \stdClass
+     * @return string
      */
     public function jsonSerialize() {
         if (ByteBuffer::$useBase64UrlEncoding) {
@@ -239,6 +239,16 @@ class ByteBuffer implements \JsonSerializable, \Serializable {
         $this->_length = \strlen($this->_data);
     }
 
+    /**
+     * (PHP 8 deprecates Serializable-Interface)
+     * @return array
+     */
+    public function __serialize() {
+        return [
+            'data' => \serialize($this->_data)
+        ];
+    }
+
     /**
      * object to string
      * @return string
@@ -247,6 +257,18 @@ class ByteBuffer implements \JsonSerializable, \Serializable {
         return $this->getHex();
     }
 
+    /**
+     * (PHP 8 deprecates Serializable-Interface)
+     * @param array $data
+     * @return void
+     */
+    public function __unserialize($data) {
+        if ($data && isset($data['data'])) {
+            $this->_data = \unserialize($data['data']);
+            $this->_length = \strlen($this->_data);
+        }
+    }
+
     // -----------------------
     // PROTECTED STATIC
     // -----------------------