diff --git a/lib/openpgp.php b/lib/openpgp.php
index 3fdd9d9..927126c 100644
--- a/lib/openpgp.php
+++ b/lib/openpgp.php
@@ -113,6 +113,13 @@ class OpenPGP {
 class OpenPGP_S2K {
   public $type, $hash_algorithm, $salt, $count;
 
+  function __construct($salt='BADSALT', $hash_algorithm=10, $count=65536, $type=3) {
+    $this->type = $type;
+    $this->hash_algorithm = $hash_algorithm;
+    $this->salt = $salt;
+    $this->count = $count;
+  }
+
   static function parse(&$input) {
     $s2k = new OpenPGP_S2k();
     switch($s2k->type = ord($input{0})) {
@@ -570,6 +577,13 @@ class OpenPGP_Packet {
 class OpenPGP_AsymmetricSessionKeyPacket extends OpenPGP_Packet {
   public $version, $keyid, $key_algorithm, $encrypted_data;
 
+  function __construct($key_algorithm='', $keyid='', $encrypted_data='', $version=3) {
+    $this->version = $version;
+    $this->keyid = substr($keyid, -16);
+    $this->key_algorithm = $key_algorithm;
+    $this->encrypted_data = $encrypted_data;
+  }
+
   function read() {
     switch($this->version = ord($this->read_byte())) {
       case 3:
@@ -1230,6 +1244,13 @@ class OpenPGP_SignaturePacket_EmbeddedSignaturePacket extends OpenPGP_SignatureP
 class OpenPGP_SymmetricSessionKeyPacket extends OpenPGP_Packet {
   public $version, $symmetric_algorithm, $s2k, $encrypted_data;
 
+  function __construct($s2k=NULL, $encrypted_data='', $symmetric_algorithm=9, $version=3) {
+    $this->version = $version;
+    $this->symmetric_algorithm = $symmetric_algorithm;
+    $this->s2k = $s2k;
+    $this->encrypted_data = $encrypted_data;
+  }
+
   function read() {
     $this->version = ord($this->read_byte());
     $this->symmetric_algorithm = ord($this->read_byte());
@@ -1775,6 +1796,10 @@ class OpenPGP_UserAttributePacket extends OpenPGP_Packet {
 class OpenPGP_IntegrityProtectedDataPacket extends OpenPGP_EncryptedDataPacket {
   public $version;
 
+  function __construct($data='', $version=1) {
+    $this->data = $data;
+  }
+
   function read() {
     $this->version = ord($this->read_byte());
     $this->data = $this->input;
@@ -1791,7 +1816,24 @@ class OpenPGP_IntegrityProtectedDataPacket extends OpenPGP_EncryptedDataPacket {
  * @see http://tools.ietf.org/html/rfc4880#section-5.14
  */
 class OpenPGP_ModificationDetectionCodePacket extends OpenPGP_Packet {
-  // TODO
+  function __construct($sha1='') {
+    $this->data = $sha1;
+  }
+
+  function read() {
+    $this->data = $this->input;
+    if(strlen($this->input) != 20) throw new Exception("Bad ModificationDetectionCodePacket");
+  }
+
+  function header_and_body() {
+    $body = $this->body(); // Get body first, we will need it's length
+    if(strlen($body) != 20) throw new Exception("Bad ModificationDetectionCodePacket");
+    return array('header' => "\xD3\x14", 'body' => $body);
+  }
+
+  function body() {
+    return $this->data;
+  }
 }
 
 /**
diff --git a/lib/openpgp_crypt_aes_tripledes.php b/lib/openpgp_crypt_aes_tripledes.php
index 8309819..46d5985 100644
--- a/lib/openpgp_crypt_aes_tripledes.php
+++ b/lib/openpgp_crypt_aes_tripledes.php
@@ -1,10 +1,49 @@
 <?php
 
 require_once dirname(__FILE__).'/openpgp.php';
+@include_once dirname(__FILE__).'/openpgp_crypt_rsa.php';
 require_once 'Crypt/AES.php';
 require_once 'Crypt/TripleDES.php';
+require_once 'Crypt/Random.php';
 
 class OpenPGP_Crypt_AES_TripleDES {
+  public static function encrypt($passphrases_and_keys, $message, $symmetric_algorithm=9) {
+    list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm);
+    $prefix = self::randomBytes($key_block_bytes);
+    $prefix .= substr($prefix, -2);
+
+    $key = self::randomBytes($key_bytes);
+    $cipher->setKey($key);
+
+    $to_encrypt = $prefix . $message->to_bytes();
+    $mdc = new OpenPGP_ModificationDetectionCodePacket(hash('sha1', $to_encrypt . "\xD3\x14", true));
+    $to_encrypt .= $mdc->to_bytes();
+    $encrypted = array(new OpenPGP_IntegrityProtectedDataPacket($cipher->encrypt($to_encrypt)));
+
+    if(!is_array($passphrases_and_keys) && !($passphrases_and_keys instanceof IteratorAggregate)) {
+      $passphrases_and_keys = (array)$passphrases_and_keys;
+    }
+
+    foreach($passphrases_and_keys as $pass) {
+      if($pass instanceof OpenPGP_PublicKeyPacket) {
+        if(!in_array($pass->algorithm, array(1,2,3))) throw new Exception("Only RSA keys are supported.");
+        $crypt_rsa = new OpenPGP_Crypt_RSA($pass);
+        $rsa = $crypt_rsa->public_key();
+        $rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
+        $esk = $rsa->encrypt(chr($symmetric_algorithm) . $key . pack('n', self::checksum($key)));
+        $esk = pack('n', OpenPGP::bitlength($esk)) . $esk;
+        array_unshift($encrypted, new OpenPGP_AsymmetricSessionKeyPacket($pass->algorithm, $pass->fingerprint(), $esk));
+      } else if(is_string($pass)) {
+        $s2k = new OpenPGP_S2K(crypt_random() . crypt_random() . crypt_random());
+        $cipher->setKey($s2k->make_key($pass, $key_bytes));
+        $esk = $cipher->encrypt(chr($symmetric_algorithm) . $key);
+        array_unshift($encrypted, new OpenPGP_SymmetricSessionKeyPacket($s2k, $esk, $symmetric_algorithm));
+      }
+    }
+
+    return new OpenPGP_Message($encrypted);
+  }
+
   public static function decryptSymmetric($pass, $m) {
     $epacket = self::getEncryptedData($m);
 
@@ -41,16 +80,13 @@ class OpenPGP_Crypt_AES_TripleDES {
     if($packet->s2k_useage == 254) {
       $chk = substr($material, -20);
       $material = substr($material, 0, -20);
-      if($chk != hash('sha1', $material)) return NULL;
+      if($chk != hash('sha1', $material, true)) return NULL;
     } else {
       $chk = unpack('n', substr($material, -2));
       $chk = reset($chk);
       $material = substr($material, 0, -2);
 
-      $mkChk = 0;
-      for($i = 0; $i < strlen($material); $i++) {
-        $mkChk = ($mkChk + ord($material{$i})) % 65536;
-      }
+      $mkChk = self::checksum($material);
       if($chk != $mkChk) return NULL;
     }
 
@@ -139,4 +175,21 @@ class OpenPGP_Crypt_AES_TripleDES {
     }
     throw new Exception("Can only decrypt EncryptedDataPacket");
   }
+
+  public static function randomBytes($n) {
+    $key = '';
+    for($i = 0; $i < $n; $i++) {
+		$key .= crypt_random();
+    }
+    $s2k = new OpenPGP_S2K(crypt_random() . crypt_random() . crypt_random());
+    return $s2k->make_key($key, $n);
+  }
+
+  public static function checksum($s) {
+    $mkChk = 0;
+    for($i = 0; $i < strlen($s); $i++) {
+      $mkChk = ($mkChk + ord($s{$i})) % 65536;
+    }
+    return $mkChk;
+  }
 }
diff --git a/phpunit.xml b/phpunit.xml
index 41b0d95..a071d34 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -15,5 +15,13 @@
     <testsuite name="KeyVerification">
       <file>tests/phpseclib_suite.php</file>
     </testsuite>
+
+    <testsuite name="Decryption">
+      <file>tests/phpseclib_suite.php</file>
+    </testsuite>
+
+    <testsuite name="Encryption">
+      <file>tests/phpseclib_suite.php</file>
+    </testsuite>
   </testsuites>
 </phpunit>
diff --git a/tests/phpseclib_suite.php b/tests/phpseclib_suite.php
index 8044fbf..e5ed903 100644
--- a/tests/phpseclib_suite.php
+++ b/tests/phpseclib_suite.php
@@ -111,3 +111,21 @@ class Decryption extends PHPUnit_Framework_TestCase {
     $this->assertSame(!!$skey, true);
   }
 }
+
+class Encryption extends PHPUnit_Framework_TestCase {
+  public function testEncryptSymmetric() {
+    $data = new OpenPGP_LiteralDataPacket('This is text.', array('format' => 'u', 'filename' => 'stuff.txt'));
+    $encrypted = OpenPGP_Crypt_AES_TripleDES::encrypt('secret', new OpenPGP_Message(array($data)));
+    $decrypted = OpenPGP_Crypt_AES_TripleDES::decryptSymmetric('secret', $encrypted);
+    $this->assertEquals($decrypted[0]->data, 'This is text.');
+  }
+
+  public function testEncryptAsymmetric() {
+    $key = OpenPGP_Message::parse(file_get_contents(dirname(__FILE__) . '/data/helloKey.gpg'));
+    $data = new OpenPGP_LiteralDataPacket('This is text.', array('format' => 'u', 'filename' => 'stuff.txt'));
+    $encrypted = OpenPGP_Crypt_AES_TripleDES::encrypt($key, new OpenPGP_Message(array($data)));
+    $decryptor = new OpenPGP_Crypt_RSA($key);
+    $decrypted = $decryptor->decrypt($encrypted);
+    $this->assertEquals($decrypted[0]->data, 'This is text.');
+  }
+}