diff --git a/phpseclib/Crypt/RSA.php b/phpseclib/Crypt/RSA.php
index 4df0b918..8eedc0bb 100644
--- a/phpseclib/Crypt/RSA.php
+++ b/phpseclib/Crypt/RSA.php
@@ -69,13 +69,6 @@
  * @link       http://phpseclib.sourceforge.net
  */
 
-/**
- * Include Math_BigInteger
- */
-if (!class_exists('Math_BigInteger')) {
-    require_once('Math/BigInteger.php');
-}
-
 /**
  * Include Crypt_Random
  */
@@ -84,14 +77,14 @@ if (!class_exists('Math_BigInteger')) {
 // call function_exists() a second time to stop the require_once from being called outside
 // of the auto loader
 if (!function_exists('crypt_random_string')) {
-    require_once('Crypt/Random.php');
+    require_once('Random.php');
 }
 
 /**
  * Include Crypt_Hash
  */
 if (!class_exists('Crypt_Hash')) {
-    require_once('Crypt/Hash.php');
+    require_once('Hash.php');
 }
 
 /**#@+
@@ -469,6 +462,10 @@ class Crypt_RSA {
      */
     function Crypt_RSA()
     {
+        if (!class_exists('Math_BigInteger')) {
+            require_once('Math/BigInteger.php');
+        }
+
         $this->configFile = CRYPT_RSA_OPENSSL_CONFIG;
 
         if ( !defined('CRYPT_RSA_MODE') ) {
diff --git a/phpseclib/File/ASN1.php b/phpseclib/File/ASN1.php
index 80f26fff..69a2ee91 100644
--- a/phpseclib/File/ASN1.php
+++ b/phpseclib/File/ASN1.php
@@ -41,13 +41,6 @@
  * @link       http://phpseclib.sourceforge.net
  */
 
-/**
- * Include Math_BigInteger
- */
-if (!class_exists('Math_BigInteger')) {
-    require_once('Math/BigInteger.php');
-}
-
 /**#@+
  * Tag Classes
  *
@@ -249,6 +242,17 @@ class File_ASN1 {
         FILE_ASN1_TYPE_VISIBLE_STRING   => 1,
     );
 
+    function File_ASN1()
+        {
+            static $static_init = null;
+            if (!$static_init) {
+                $static_init = true;
+                if (!class_exists('Math_BigInteger')) {
+                    require_once('Math/BigInteger.php');
+                }
+            }
+        }
+
     /**
      * Parse BER-encoding
      *
diff --git a/phpseclib/File/X509.php b/phpseclib/File/X509.php
index 4212f37e..ee461aab 100644
--- a/phpseclib/File/X509.php
+++ b/phpseclib/File/X509.php
@@ -48,7 +48,7 @@
  * Include File_ASN1
  */
 if (!class_exists('File_ASN1')) {
-    require_once('File/ASN1.php');
+    require_once('ASN1.php');
 }
 
 /**
@@ -4345,4 +4345,4 @@ class File_X509 {
         $temp = preg_match('#^[a-zA-Z\d/+]*={0,2}$#', $temp) ? base64_decode($temp) : false;
         return $temp != false ? $temp : $str;
     }
-}
\ No newline at end of file
+}
diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index f2c083fe..f9ae7441 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -58,7 +58,7 @@
  * Include Net_SSH2
  */
 if (!class_exists('Net_SSH2')) {
-    require_once('Net/SSH2.php');
+    require_once('SSH2.php');
 }
 
 /**#@+
diff --git a/phpseclib/Net/SFTP/Stream.php b/phpseclib/Net/SFTP/Stream.php
index 43febd4e..23448570 100644
--- a/phpseclib/Net/SFTP/Stream.php
+++ b/phpseclib/Net/SFTP/Stream.php
@@ -34,13 +34,6 @@
  * @link       http://phpseclib.sourceforge.net
  */
 
-/**
- * Include Net_SSH2
- */
-if (!class_exists('Net_SFTP')) {
-    require_once('Net/SFTP.php');
-}
-
 /**
  * SFTP Stream Wrapper
  *
@@ -134,6 +127,18 @@ class Net_SFTP_Stream {
      */
     var $notification;
 
+    /**
+     * The Constructor
+     *
+     * @access public
+     */
+    function Net_SFTP_Stream()
+    {
+        if (!class_exists('Net_SFTP')) {
+            require_once('Net/SFTP.php');
+        }
+    }
+
     /**
      * Path Parser
      *
@@ -756,4 +761,6 @@ class Net_SFTP_Stream {
     }
 }
 
-stream_wrapper_register('sftp', 'Net_SFTP_Stream');
+if (function_exists('stream_wrapper_register')) {
+    stream_wrapper_register('sftp', 'Net_SFTP_Stream');
+}
diff --git a/phpseclib/Net/SSH1.php b/phpseclib/Net/SSH1.php
index d80e2ba9..89b5aa2c 100644
--- a/phpseclib/Net/SSH1.php
+++ b/phpseclib/Net/SSH1.php
@@ -66,52 +66,6 @@
  * @link       http://phpseclib.sourceforge.net
  */
 
-/**
- * Include Math_BigInteger
- *
- * Used to do RSA encryption.
- */
-if (!class_exists('Math_BigInteger')) {
-    require_once('Math/BigInteger.php');
-}
-
-/**
- * Include Crypt_Null
- */
-//require_once('Crypt/Null.php');
-
-/**
- * Include Crypt_DES
- */
-if (!class_exists('Crypt_DES')) {
-    require_once('Crypt/DES.php');
-}
-
-/**
- * Include Crypt_TripleDES
- */
-if (!class_exists('Crypt_TripleDES')) {
-    require_once('Crypt/TripleDES.php');
-}
-
-/**
- * Include Crypt_RC4
- */
-if (!class_exists('Crypt_RC4')) {
-    require_once('Crypt/RC4.php');
-}
-
-/**
- * Include Crypt_Random
- */
-// the class_exists() will only be called if the crypt_random_string function hasn't been defined and
-// will trigger a call to __autoload() if you're wanting to auto-load classes
-// call function_exists() a second time to stop the require_once from being called outside
-// of the auto loader
-if (!function_exists('crypt_random_string') && !class_exists('Crypt_Random') && !function_exists('crypt_random_string')) {
-    require_once('Crypt/Random.php');
-}
-
 /**#@+
  * Encryption Methods
  *
@@ -495,6 +449,19 @@ class Net_SSH1 {
      */
     function Net_SSH1($host, $port = 22, $timeout = 10, $cipher = NET_SSH1_CIPHER_3DES)
     {
+        if (!class_exists('Math_BigInteger')) {
+            require_once('Math/BigInteger.php');
+        }
+
+        // Include Crypt_Random
+        // the class_exists() will only be called if the crypt_random_string function hasn't been defined and
+        // will trigger a call to __autoload() if you're wanting to auto-load classes
+        // call function_exists() a second time to stop the require_once from being called outside
+        // of the auto loader
+        if (!function_exists('crypt_random_string') && !class_exists('Crypt_Random') && !function_exists('crypt_random_string')) {
+            require_once('Crypt/Random.php');
+        }
+
         $this->protocol_flags = array(
             1  => 'NET_SSH1_MSG_DISCONNECT',
             2  => 'NET_SSH1_SMSG_PUBLIC_KEY',
@@ -636,18 +603,27 @@ class Net_SSH1 {
             //    $this->crypto = new Crypt_Null();
             //    break;
             case NET_SSH1_CIPHER_DES:
+                if (!class_exists('Crypt_DES')) {
+                    require_once('Crypt/DES.php');
+                }
                 $this->crypto = new Crypt_DES();
                 $this->crypto->disablePadding();
                 $this->crypto->enableContinuousBuffer();
                 $this->crypto->setKey(substr($session_key, 0,  8));
                 break;
             case NET_SSH1_CIPHER_3DES:
+                if (!class_exists('Crypt_TripleDES')) {
+                    require_once('Crypt/TripleDES.php');
+                }
                 $this->crypto = new Crypt_TripleDES(CRYPT_DES_MODE_3CBC);
                 $this->crypto->disablePadding();
                 $this->crypto->enableContinuousBuffer();
                 $this->crypto->setKey(substr($session_key, 0, 24));
                 break;
             //case NET_SSH1_CIPHER_RC4:
+            //    if (!class_exists('Crypt_RC4')) {
+            //        require_once('Crypt/RC4.php');
+            //    }
             //    $this->crypto = new Crypt_RC4();
             //    $this->crypto->enableContinuousBuffer();
             //    $this->crypto->setKey(substr($session_key, 0,  16));
diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index 7243447a..d3688818 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -68,64 +68,6 @@
  * @link       http://phpseclib.sourceforge.net
  */
 
-/**
- * Include Math_BigInteger
- *
- * Used to do Diffie-Hellman key exchange and DSA/RSA signature verification.
- */
-if (!class_exists('Math_BigInteger')) {
-    require_once('Math/BigInteger.php');
-}
-
-/**
- * Include Crypt_Random
- */
-if (!function_exists('crypt_random_string')) {
-    require_once('Crypt/Random.php');
-}
-
-/**
- * Include Crypt_Hash
- */
-if (!class_exists('Crypt_Hash')) {
-    require_once('Crypt/Hash.php');
-}
-
-/**
- * Include Crypt_TripleDES
- */
-if (!class_exists('Crypt_TripleDES')) {
-    require_once('Crypt/TripleDES.php');
-}
-
-/**
- * Include Crypt_RC4
- */
-if (!class_exists('Crypt_RC4')) {
-    require_once('Crypt/RC4.php');
-}
-
-/**
- * Include Crypt_AES
- */
-if (!class_exists('Crypt_AES')) {
-    require_once('Crypt/AES.php');
-}
-
-/**
- * Include Crypt_Twofish
- */
-if (!class_exists('Crypt_Twofish')) {
-    require_once('Crypt/Twofish.php');
-}
-
-/**
- * Include Crypt_Blowfish
- */
-if (!class_exists('Crypt_Blowfish')) {
-    require_once('Crypt/Blowfish.php');
-}
-
 /**#@+
  * Execution Bitmap Masks
  *
@@ -791,6 +733,20 @@ class Net_SSH2 {
      */
     function Net_SSH2($host, $port = 22, $timeout = 10)
     {
+        // Include Math_BigInteger
+        // Used to do Diffie-Hellman key exchange and DSA/RSA signature verification.
+        if (!class_exists('Math_BigInteger')) {
+            require_once('Math/BigInteger.php');
+        }
+
+        if (!function_exists('crypt_random_string')) {
+            require_once('Crypt/Random.php');
+        }
+
+        if (!class_exists('Crypt_Hash')) {
+            require_once('Crypt/Hash.php');
+        }
+
         $this->last_packet = strtok(microtime(), ' ') + strtok(''); // == microtime(true) in PHP5
         $this->message_numbers = array(
             1 => 'NET_SSH2_MSG_DISCONNECT',
@@ -1334,30 +1290,48 @@ class Net_SSH2 {
 
         switch ($encrypt) {
             case '3des-cbc':
+                if (!class_exists('Crypt_TripleDES')) {
+                    require_once('Crypt/TripleDES.php');
+                }
                 $this->encrypt = new Crypt_TripleDES();
                 // $this->encrypt_block_size = 64 / 8 == the default
                 break;
             case '3des-ctr':
+                if (!class_exists('Crypt_TripleDES')) {
+                    require_once('Crypt/TripleDES.php');
+                }
                 $this->encrypt = new Crypt_TripleDES(CRYPT_DES_MODE_CTR);
                 // $this->encrypt_block_size = 64 / 8 == the default
                 break;
             case 'aes256-cbc':
             case 'aes192-cbc':
             case 'aes128-cbc':
+                if (!class_exists('Crypt_AES')) {
+                    require_once('Crypt/AES.php');
+                }
                 $this->encrypt = new Crypt_AES();
                 $this->encrypt_block_size = 16; // eg. 128 / 8
                 break;
             case 'aes256-ctr':
             case 'aes192-ctr':
             case 'aes128-ctr':
+                if (!class_exists('Crypt_AES')) {
+                    require_once('Crypt/AES.php');
+                }
                 $this->encrypt = new Crypt_AES(CRYPT_AES_MODE_CTR);
                 $this->encrypt_block_size = 16; // eg. 128 / 8
                 break;
             case 'blowfish-cbc':
+                if (!class_exists('Crypt_Blowfish')) {
+                    require_once('Crypt/Blowfish.php');
+                }
                 $this->encrypt = new Crypt_Blowfish();
                 $this->encrypt_block_size = 8;
                 break;
             case 'blowfish-ctr':
+                if (!class_exists('Crypt_Blowfish')) {
+                    require_once('Crypt/Blowfish.php');
+                }
                 $this->encrypt = new Crypt_Blowfish(CRYPT_BLOWFISH_MODE_CTR);
                 $this->encrypt_block_size = 8;
                 break;
@@ -1365,18 +1339,27 @@ class Net_SSH2 {
             case 'twofish192-cbc':
             case 'twofish256-cbc':
             case 'twofish-cbc':
+                if (!class_exists('Crypt_Twofish')) {
+                    require_once('Crypt/Twofish.php');
+                }
                 $this->encrypt = new Crypt_Twofish();
                 $this->encrypt_block_size = 16;
                 break;
             case 'twofish128-ctr':
             case 'twofish192-ctr':
             case 'twofish256-ctr':
+                if (!class_exists('Crypt_Twofish')) {
+                    require_once('Crypt/Twofish.php');
+                }
                 $this->encrypt = new Crypt_Twofish(CRYPT_TWOFISH_MODE_CTR);
                 $this->encrypt_block_size = 16;
                 break;
             case 'arcfour':
             case 'arcfour128':
             case 'arcfour256':
+                if (!class_exists('Crypt_RC4')) {
+                    require_once('Crypt/RC4.php');
+                }
                 $this->encrypt = new Crypt_RC4();
                 break;
             case 'none';
@@ -1385,28 +1368,46 @@ class Net_SSH2 {
 
         switch ($decrypt) {
             case '3des-cbc':
+                if (!class_exists('Crypt_TripleDES')) {
+                    require_once('Crypt/TripleDES.php');
+                }
                 $this->decrypt = new Crypt_TripleDES();
                 break;
             case '3des-ctr':
+                if (!class_exists('Crypt_TripleDES')) {
+                    require_once('Crypt/TripleDES.php');
+                }
                 $this->decrypt = new Crypt_TripleDES(CRYPT_DES_MODE_CTR);
                 break;
             case 'aes256-cbc':
             case 'aes192-cbc':
             case 'aes128-cbc':
+                if (!class_exists('Crypt_AES')) {
+                    require_once('Crypt/AES.php');
+                }
                 $this->decrypt = new Crypt_AES();
                 $this->decrypt_block_size = 16;
                 break;
             case 'aes256-ctr':
             case 'aes192-ctr':
             case 'aes128-ctr':
+                if (!class_exists('Crypt_AES')) {
+                    require_once('Crypt/AES.php');
+                }
                 $this->decrypt = new Crypt_AES(CRYPT_AES_MODE_CTR);
                 $this->decrypt_block_size = 16;
                 break;
             case 'blowfish-cbc':
+                if (!class_exists('Crypt_Blowfish')) {
+                    require_once('Crypt/Blowfish.php');
+                }
                 $this->decrypt = new Crypt_Blowfish();
                 $this->decrypt_block_size = 8;
                 break;
             case 'blowfish-ctr':
+                if (!class_exists('Crypt_Blowfish')) {
+                    require_once('Crypt/Blowfish.php');
+                }
                 $this->decrypt = new Crypt_Blowfish(CRYPT_BLOWFISH_MODE_CTR);
                 $this->decrypt_block_size = 8;
                 break;
@@ -1414,18 +1415,27 @@ class Net_SSH2 {
             case 'twofish192-cbc':
             case 'twofish256-cbc':
             case 'twofish-cbc':
+                if (!class_exists('Crypt_Twofish')) {
+                    require_once('Crypt/Twofish.php');
+                }
                 $this->decrypt = new Crypt_Twofish();
                 $this->decrypt_block_size = 16;
                 break;
             case 'twofish128-ctr':
             case 'twofish192-ctr':
             case 'twofish256-ctr':
+                if (!class_exists('Crypt_Twofish')) {
+                    require_once('Crypt/Twofish.php');
+                }
                 $this->decrypt = new Crypt_Twofish(CRYPT_TWOFISH_MODE_CTR);
                 $this->decrypt_block_size = 16;
                 break;
             case 'arcfour':
             case 'arcfour128':
             case 'arcfour256':
+                if (!class_exists('Crypt_RC4')) {
+                    require_once('Crypt/RC4.php');
+                }
                 $this->decrypt = new Crypt_RC4();
                 break;
             case 'none';