diff --git a/lib/OpenPgP/CompressedDataPacket.php b/lib/OpenPgP/CompressedDataPacket.php
index 89ab1e9..3f28492 100644
--- a/lib/OpenPgP/CompressedDataPacket.php
+++ b/lib/OpenPgP/CompressedDataPacket.php
@@ -51,19 +51,19 @@ class CompressedDataPacket extends Packet implements \IteratorAggregate, \ArrayA
 
 		switch($this->algorithm) {
 			case 0:
-				$body .= $this->data->to_bytes();
+				$body .= (string)$this->data;
 				break;
 
 			case 1:
-				$body .= gzdeflate($this->data->to_bytes());
+				$body .= gzdeflate((string)$this->data);
 				break;
 
 			case 2:
-				$body .= gzcompress($this->data->to_bytes());
+				$body .= gzcompress((string)$this->data);
 				break;
 
 			case 3:
-				$body .= bzcompress($this->data->to_bytes());
+				$body .= bzcompress((string)$this->data);
 				break;
 
 			default:
diff --git a/lib/OpenPgP/Crypt/Symmetric.php b/lib/OpenPgP/Crypt/Symmetric.php
index 490491a..add63a9 100644
--- a/lib/OpenPgP/Crypt/Symmetric.php
+++ b/lib/OpenPgP/Crypt/Symmetric.php
@@ -32,7 +32,7 @@ class Symmetric
 		$key = Random::string($key_bytes);
 		$cipher->setKey($key);
 
-		$to_encrypt = $prefix.$message->to_bytes();
+		$to_encrypt = $prefix.$message;
 
 		$mdc = new OpenPGP\ModificationDetectionCodePacket(hash('sha1',$to_encrypt."\xD3\x14",true));
 		$to_encrypt .= (string)$mdc;
diff --git a/lib/OpenPgP/Message.php b/lib/OpenPgP/Message.php
index 8c7dac8..a20b9c6 100644
--- a/lib/OpenPgP/Message.php
+++ b/lib/OpenPgP/Message.php
@@ -198,17 +198,6 @@ class Message implements \IteratorAggregate,\ArrayAccess
 		return $final_sigs;
 	}
 
-	public function to_bytes(): string
-	{
-		$bytes = '';
-
-		foreach ($this as $p) {
-			$bytes .= (string)$p;
-		}
-
-		return $bytes;
-	}
-
 	/**
 	 * Function to extract verified signatures
 	 *
diff --git a/lib/OpenPgP/S2K.php b/lib/OpenPgP/S2K.php
index cb9a4f1..ae52127 100644
--- a/lib/OpenPgP/S2K.php
+++ b/lib/OpenPgP/S2K.php
@@ -43,7 +43,7 @@ class S2K
 		return $s2k;
 	}
 
-	function to_bytes()
+	function __toString()
 	{
 		$bytes = chr($this->type);
 
diff --git a/lib/OpenPgP/SecretKeyPacket.php b/lib/OpenPgP/SecretKeyPacket.php
index 490dccd..d8fc27d 100644
--- a/lib/OpenPgP/SecretKeyPacket.php
+++ b/lib/OpenPgP/SecretKeyPacket.php
@@ -29,7 +29,7 @@ class SecretKeyPacket extends PublicKeyPacket
 		$secret_material = NULL;
 		if($this->s2k_useage == 255 || $this->s2k_useage == 254) {
 			$bytes .= chr($this->symmetric_algorithm);
-			$bytes .= $this->s2k->to_bytes();
+			$bytes .= (string)$this->s2k;
 		}
 		if($this->s2k_useage > 0) {
 			$bytes .= $this->encrypted_data;
diff --git a/lib/OpenPgP/SymmetricSessionKeyPacket.php b/lib/OpenPgP/SymmetricSessionKeyPacket.php
index ca1418c..b36c947 100644
--- a/lib/OpenPgP/SymmetricSessionKeyPacket.php
+++ b/lib/OpenPgP/SymmetricSessionKeyPacket.php
@@ -23,8 +23,7 @@ class SymmetricSessionKeyPacket extends Packet
 
 	function body()
 	{
-		return chr($this->version) . chr($this->symmetric_algorithm) .
-			$this->s2k->to_bytes() . $this->encrypted_data;
+		return chr($this->version).chr($this->symmetric_algorithm).$this->s2k.$this->encrypted_data;
 	}
 
 	function read()