diff --git a/phpseclib/Crypt/AES.php b/phpseclib/Crypt/AES.php
index 40e78ede..8521eb5e 100644
--- a/phpseclib/Crypt/AES.php
+++ b/phpseclib/Crypt/AES.php
@@ -65,6 +65,7 @@ class AES extends Rijndael
      *
      * @see \phpseclib\Crypt\Rijndael::setBlockLength()
      * @access public
+     * @param int $length
      * @throws \BadMethodCallException anytime it's called
      */
     function setBlockLength($length)
@@ -90,7 +91,7 @@ class AES extends Rijndael
             case 256:
                 break;
             default:
-                throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16, 24 or 32 supported');
+                throw new \LengthException('Key of size ' . $length . ' not supported by this algorithm. Only keys of sizes 128, 192 or 256 supported');
         }
         parent::setKeyLength($length);
     }
diff --git a/phpseclib/Crypt/Base.php b/phpseclib/Crypt/Base.php
index 9ef68546..92a6f62b 100644
--- a/phpseclib/Crypt/Base.php
+++ b/phpseclib/Crypt/Base.php
@@ -793,7 +793,7 @@ abstract class Base
                 $this->changed = false;
             }
             if ($this->enchanged) {
-                mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
+                mcrypt_generic_init($this->enmcrypt, $this->key, $this->_getIV($this->encryptIV));
                 $this->enchanged = false;
             }
 
@@ -856,7 +856,7 @@ abstract class Base
             $ciphertext = mcrypt_generic($this->enmcrypt, $plaintext);
 
             if (!$this->continuousBuffer) {
-                mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV);
+                mcrypt_generic_init($this->enmcrypt, $this->key, $this->_getIV($this->encryptIV));
             }
 
             return $ciphertext;
@@ -1010,8 +1010,8 @@ abstract class Base
      */
     function decrypt($ciphertext)
     {
-        if ($this->paddable) {
-            throw new \LengthException('The ciphertext length (' . strlen($ciphertext) . ') needs to be a multiple of the block size (' . $this->block_length . ')');
+        if ($this->paddable && strlen($ciphertext) % $this->block_size) {
+            throw new \LengthException('The ciphertext length (' . strlen($ciphertext) . ') needs to be a multiple of the block size (' . $this->block_size . ')');
         }
 
         if ($this->engine === self::ENGINE_OPENSSL) {
@@ -1104,7 +1104,7 @@ abstract class Base
                 $this->changed = false;
             }
             if ($this->dechanged) {
-                mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
+                mcrypt_generic_init($this->demcrypt, $this->key, $this->_getIV($this->decryptIV));
                 $this->dechanged = false;
             }
 
@@ -1149,7 +1149,7 @@ abstract class Base
             $plaintext = mdecrypt_generic($this->demcrypt, $ciphertext);
 
             if (!$this->continuousBuffer) {
-                mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV);
+                mcrypt_generic_init($this->demcrypt, $this->key, $this->_getIV($this->decryptIV));
             }
 
             return $this->paddable ? $this->_unpad($plaintext) : $plaintext;
@@ -1286,6 +1286,22 @@ abstract class Base
         return $this->paddable ? $this->_unpad($plaintext) : $plaintext;
     }
 
+    /**
+     * Get the IV
+     *
+     * mcrypt requires an IV even if ECB is used
+     *
+     * @see self::encrypt()
+     * @see self::decrypt()
+     * @param string $iv
+     * @return string
+     * @access private
+     */
+    function _getIV($iv)
+    {
+        return $this->mode == self::MODE_ECB ? str_repeat("\0", $this->block_size) : $iv;
+    }
+
     /**
      * OpenSSL CTR Processor
      *
diff --git a/phpseclib/Crypt/RC4.php b/phpseclib/Crypt/RC4.php
index a2cb80ab..3da70b6e 100644
--- a/phpseclib/Crypt/RC4.php
+++ b/phpseclib/Crypt/RC4.php
@@ -209,7 +209,7 @@ class RC4 extends Base
             throw new \LengthException('Key size of ' . $length . ' bytes is not supported by RC4. Keys must be between 1 and 256 bytes long');
         }
 
-        parent::setKey($length);
+        parent::setKey($key);
     }
 
     /**
diff --git a/phpseclib/Crypt/RSA/PKCS.php b/phpseclib/Crypt/RSA/PKCS.php
index c019b52b..9d3e6425 100644
--- a/phpseclib/Crypt/RSA/PKCS.php
+++ b/phpseclib/Crypt/RSA/PKCS.php
@@ -264,7 +264,7 @@ abstract class PKCS
                         return false;
                     }
 
-                    $crypto = new DES();
+                    $crypto = new DES(DES::MODE_CBC);
                     $crypto->setPassword($password, 'pbkdf1', 'md5', $salt, $iterationCount);
                     $key = $crypto->decrypt($key);
                     if ($key === false) {
diff --git a/phpseclib/Crypt/RSA/PKCS8.php b/phpseclib/Crypt/RSA/PKCS8.php
index 9de3ca01..164fca19 100644
--- a/phpseclib/Crypt/RSA/PKCS8.php
+++ b/phpseclib/Crypt/RSA/PKCS8.php
@@ -107,7 +107,7 @@ class PKCS8 extends PKCS
             $salt = Random::string(8);
             $iterationCount = 2048;
 
-            $crypto = new DES();
+            $crypto = new DES(DES::MODE_CBC);
             $crypto->setPassword($password, 'pbkdf1', 'md5', $salt, $iterationCount);
             $RSAPrivateKey = $crypto->encrypt($RSAPrivateKey);
 
diff --git a/phpseclib/Crypt/RSA/PuTTY.php b/phpseclib/Crypt/RSA/PuTTY.php
index 71170110..302eb2b1 100644
--- a/phpseclib/Crypt/RSA/PuTTY.php
+++ b/phpseclib/Crypt/RSA/PuTTY.php
@@ -126,7 +126,7 @@ class PuTTY
         switch ($encryption) {
             case 'aes256-cbc':
                 $symkey = static::generateSymmetricKey($password, 32);
-                $crypto = new AES();
+                $crypto = new AES(AES::MODE_CBC);
         }
 
         if ($encryption != 'none') {
diff --git a/phpseclib/Crypt/TripleDES.php b/phpseclib/Crypt/TripleDES.php
index 3772cf3d..29c6eb9d 100644
--- a/phpseclib/Crypt/TripleDES.php
+++ b/phpseclib/Crypt/TripleDES.php
@@ -275,7 +275,7 @@ class TripleDES extends DES
         $this->changed = true;
         $this->_setEngine();
 
-        if ($this->mode_3cbc && $length > 8) {
+        if ($this->mode_3cbc) {
             $this->des[0]->setKey(substr($key,  0, 8));
             $this->des[1]->setKey(substr($key,  8, 8));
             $this->des[2]->setKey(substr($key, 16, 8));
diff --git a/phpseclib/Net/SSH1.php b/phpseclib/Net/SSH1.php
index 5379baaf..2a8c1d8d 100644
--- a/phpseclib/Net/SSH1.php
+++ b/phpseclib/Net/SSH1.php
@@ -662,6 +662,7 @@ class SSH1
                 $this->crypto->disablePadding();
                 $this->crypto->enableContinuousBuffer();
                 $this->crypto->setKey(substr($session_key, 0,  8));
+                // "The iv (initialization vector) is initialized to all zeroes."
                 $this->crypto->setIV(str_repeat("\0", 8));
                 break;
             case self::CIPHER_3DES:
@@ -669,6 +670,7 @@ class SSH1
                 $this->crypto->disablePadding();
                 $this->crypto->enableContinuousBuffer();
                 $this->crypto->setKey(substr($session_key, 0, 24));
+                // "All three initialization vectors are initialized to zero."
                 $this->crypto->setIV(str_repeat("\0", 8));
                 break;
             //case self::CIPHER_RC4:
diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index fe9d15b5..7111b860 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -1815,26 +1815,26 @@ class SSH2
     {
         switch ($algorithm) {
             case '3des-cbc':
-                return new TripleDES();
+                return new TripleDES(Base::MODE_CBC);
             case '3des-ctr':
                 return new TripleDES(Base::MODE_CTR);
             case 'aes256-cbc':
             case 'aes192-cbc':
             case 'aes128-cbc':
-                return new Rijndael();
+                return new Rijndael(Base::MODE_CBC);
             case 'aes256-ctr':
             case 'aes192-ctr':
             case 'aes128-ctr':
                 return new Rijndael(Base::MODE_CTR);
             case 'blowfish-cbc':
-                return new Blowfish();
+                return new Blowfish(Base::MODE_CBC);
             case 'blowfish-ctr':
                 return new Blowfish(Base::MODE_CTR);
             case 'twofish128-cbc':
             case 'twofish192-cbc':
             case 'twofish256-cbc':
             case 'twofish-cbc':
-                return new Twofish();
+                return new Twofish(Base::MODE_CBC);
             case 'twofish128-ctr':
             case 'twofish192-ctr':
             case 'twofish256-ctr':
diff --git a/tests/Unit/Crypt/AES/TestCase.php b/tests/Unit/Crypt/AES/TestCase.php
index 0550b4e2..d89516ea 100644
--- a/tests/Unit/Crypt/AES/TestCase.php
+++ b/tests/Unit/Crypt/AES/TestCase.php
@@ -388,7 +388,7 @@ abstract class Unit_Crypt_AES_TestCase extends PhpseclibTestCase
      */
     public function testContinuousBuffer()
     {
-        $aes = new AES();
+        $aes = new AES(AES::MODE_CBC);
         $aes->disablePadding();
         $aes->enableContinuousBuffer();
         $aes->setIV(pack('H*', '0457bdb4a6712986688349a29eb82535'));