use a dedicated exception class for throwing exceptions on decrypt failure

src/network/mcpe/NetworkSession.php

@@ -36,6 +36,7 @@ use pocketmine\math\Vector3;
 use pocketmine\network\BadPacketException;
 use pocketmine\network\mcpe\compression\CompressBatchPromise;
 use pocketmine\network\mcpe\compression\Zlib;
+use pocketmine\network\mcpe\encryption\DecryptionException;
 use pocketmine\network\mcpe\encryption\NetworkCipher;
 use pocketmine\network\mcpe\encryption\PrepareEncryptionTask;
 use pocketmine\network\mcpe\handler\DeathPacketHandler;
@@ -261,7 +262,7 @@ class NetworkSession{
 			Timings::$playerNetworkReceiveDecryptTimer->startTiming();
 			try{
 				$payload = $this->cipher->decrypt($payload);
-			}catch(\UnexpectedValueException $e){
+			}catch(DecryptionException $e){
 				$this->logger->debug("Encrypted packet: " . base64_encode($payload));
 				throw BadPacketException::wrap($e, "Packet decryption error");
 			}finally{

src/network/mcpe/encryption/DecryptionException.php

@@ -0,0 +1,28 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\network\mcpe\encryption;
+
+final class DecryptionException extends \RuntimeException{
+
+}

src/network/mcpe/encryption/NetworkCipher.php

@@ -65,17 +65,17 @@ class NetworkCipher{
 	}
 
 	/**
-	 * @throws \UnexpectedValueException
+	 * @throws DecryptionException
 	 */
 	public function decrypt(string $encrypted) : string{
 		if(strlen($encrypted) < 9){
-			throw new \UnexpectedValueException("Payload is too short");
+			throw new DecryptionException("Payload is too short");
 		}
 		$decrypted = $this->decryptCipher->decryptUpdate($encrypted);
 		$payload = substr($decrypted, 0, -8);
 
 		if(($expected = $this->calculateChecksum($this->decryptCounter++, $payload)) !== ($actual = substr($decrypted, -8))){
-			throw new \UnexpectedValueException("Encrypted payload has invalid checksum (expected " . bin2hex($expected) . ", got " . bin2hex($actual) . ")");
+			throw new DecryptionException("Encrypted payload has invalid checksum (expected " . bin2hex($expected) . ", got " . bin2hex($actual) . ")");
 		}
 
 		return $payload;