diff --git a/phpseclib/Crypt/Base.php b/phpseclib/Crypt/Base.php
index 3a8d7ed0..05ffa636 100644
--- a/phpseclib/Crypt/Base.php
+++ b/phpseclib/Crypt/Base.php
@@ -506,12 +506,16 @@ abstract class Base
             $this->use_inline_crypt = version_compare(PHP_VERSION, '5.3.0') >= 0 || function_exists('create_function');
         }
 
+        if (!defined('PHP_INT_SIZE')) {
+            define('PHP_INT_SIZE', 4);
+        }
+
         if (!defined('CRYPT_BASE_USE_REG_INTVAL')) {
             switch (true) {
                 // PHP_OS & "\xDF\xDF\xDF" == strtoupper(substr(PHP_OS, 0, 3)), but a lot faster
                 case (PHP_OS & "\xDF\xDF\xDF") === 'WIN':
                 case (php_uname('m') & "\xDF\xDF\xDF") != 'ARM':
-                case defined('PHP_INT_SIZE') && PHP_INT_SIZE == 8:
+                case PHP_INT_SIZE == 8:
                     define('CRYPT_BASE_USE_REG_INTVAL', true);
                     break;
                 case (php_uname('m') & "\xDF\xDF\xDF") == 'ARM':
@@ -2858,7 +2862,7 @@ abstract class Base
      */
     function safe_intval($x)
     {
-        if (!CRYPT_BASE_USE_REG_INTVAL || is_int($x)) {
+        if (is_int($x)) {
             return $x;
         }
         return (fmod($x, 0x80000000) & 0x7FFFFFFF) |
@@ -2874,7 +2878,7 @@ abstract class Base
     function safe_intval_inline()
     {
         if (CRYPT_BASE_USE_REG_INTVAL) {
-            return '%s';
+            return PHP_INT_SIZE == 4 ? 'intval(%s)' : '%s';
         }
 
         $safeint = '(is_int($temp = %s) ? $temp : (fmod($temp, 0x80000000) & 0x7FFFFFFF) | ';
diff --git a/phpseclib/Crypt/Blowfish.php b/phpseclib/Crypt/Blowfish.php
index 8c902385..eca53aae 100644
--- a/phpseclib/Crypt/Blowfish.php
+++ b/phpseclib/Crypt/Blowfish.php
@@ -373,6 +373,41 @@ class Blowfish extends Base
      */
     var $key_length = 16;
 
+    /**
+     * Default Constructor.
+     *
+     * Determines whether or not the mcrypt extension should be used.
+     *
+     * $mode could be:
+     *
+     * - CRYPT_MODE_ECB
+     *
+     * - CRYPT_MODE_CBC
+     *
+     * - CRYPT_MODE_CTR
+     *
+     * - CRYPT_MODE_CFB
+     *
+     * - CRYPT_MODE_OFB
+     *
+     * (or the alias constants of the chosen cipher, for example for AES: CRYPT_AES_MODE_ECB or CRYPT_AES_MODE_CBC ...)
+     *
+     * If not explicitly set, CRYPT_MODE_CBC will be used.
+     *
+     * @param int $mode
+     * @access public
+     */
+    function __construct($mode = CRYPT_MODE_CBC)
+    {
+        parent::__construct($mode);
+
+        $this->sbox0 = array_map('intval', $this->sbox0);
+        $this->sbox1 = array_map('intval', $this->sbox1);
+        $this->sbox2 = array_map('intval', $this->sbox2);
+        $this->sbox3 = array_map('intval', $this->sbox3);
+        $this->parray = array_map('intval', $this->parray);
+    }
+
     /**
      * Sets the key length.
      *
@@ -457,7 +492,7 @@ class Blowfish extends Base
                     $j = 0;
                 }
             }
-            $this->bctx['p'][] = $this->parray[$i] ^ $data;
+            $this->bctx['p'][] = $this->parray[$i] ^ intval($data);
         }
 
         // encrypt the zero-string, replace P1 and P2 with the encrypted data,
@@ -528,7 +563,8 @@ class Blowfish extends Base
      */
     function bcrypt_pbkdf($pass, $salt, $keylen, $rounds)
     {
-        if (!CRYPT_BASE_USE_REG_INTVAL) {
+        if (PHP_INT_SIZE == 4) {
+            user_error('bcrypt is far too slow to be practical on 32-bit versions of PHP');
             return false;
         }
 
diff --git a/phpseclib/Crypt/DES.php b/phpseclib/Crypt/DES.php
index 9a8225fb..a19d1a0b 100644
--- a/phpseclib/Crypt/DES.php
+++ b/phpseclib/Crypt/DES.php
@@ -1246,9 +1246,9 @@ class DES extends Base
                       $pc2mapd3[($d >>  8) & 0xFF] | $pc2mapd4[ $d        & 0xFF];
 
                 // Reorder: odd bytes/even bytes. Push the result in key schedule.
-                $val1 = ( $cp        & 0xFF000000) | (($cp <<  8) & 0x00FF0000) |
+                $val1 = ( $cp        & intval(0xFF000000)) | (($cp <<  8) & 0x00FF0000) |
                         (($dp >> 16) & 0x0000FF00) | (($dp >>  8) & 0x000000FF);
-                $val2 = (($cp <<  8) & 0xFF000000) | (($cp << 16) & 0x00FF0000) |
+                $val2 = (($cp <<  8) & intval(0xFF000000)) | (($cp << 16) & 0x00FF0000) |
                         (($dp >>  8) & 0x0000FF00) | ( $dp        & 0x000000FF);
                 $keys[$des_round][self::ENCRYPT][       ] = $val1;
                 $keys[$des_round][self::DECRYPT][$ki - 1] = $val1;
diff --git a/phpseclib/Crypt/Rijndael.php b/phpseclib/Crypt/Rijndael.php
index 3648a197..7a6be2a6 100644
--- a/phpseclib/Crypt/Rijndael.php
+++ b/phpseclib/Crypt/Rijndael.php
@@ -340,7 +340,7 @@ class Rijndael extends Base
         $k = $c[2];
         $l = $c[3];
         while ($i < $Nb) {
-            $temp[$i] = ($state[$i] & 0xFF000000) ^
+            $temp[$i] = ($state[$i] & intval(0xFF000000)) ^
                         ($state[$j] & 0x00FF0000) ^
                         ($state[$k] & 0x0000FF00) ^
                         ($state[$l] & 0x000000FF) ^
@@ -426,7 +426,7 @@ class Rijndael extends Base
         $l = $Nb - $c[3];
 
         while ($i < $Nb) {
-            $word = ($state[$i] & 0xFF000000) |
+            $word = ($state[$i] & intval(0xFF000000)) |
                     ($state[$j] & 0x00FF0000) |
                     ($state[$k] & 0x0000FF00) |
                     ($state[$l] & 0x000000FF);
@@ -465,14 +465,19 @@ class Rijndael extends Base
     {
         // Each number in $rcon is equal to the previous number multiplied by two in Rijndael's finite field.
         // See http://en.wikipedia.org/wiki/Finite_field_arithmetic#Multiplicative_inverse
-        static $rcon = array(0,
-            0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000,
-            0x20000000, 0x40000000, 0x80000000, 0x1B000000, 0x36000000,
-            0x6C000000, 0xD8000000, 0xAB000000, 0x4D000000, 0x9A000000,
-            0x2F000000, 0x5E000000, 0xBC000000, 0x63000000, 0xC6000000,
-            0x97000000, 0x35000000, 0x6A000000, 0xD4000000, 0xB3000000,
-            0x7D000000, 0xFA000000, 0xEF000000, 0xC5000000, 0x91000000
-        );
+        static $rcon;
+
+        if (!isset($rcon)) {
+            $rcon = array(0,
+                0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000,
+                0x20000000, 0x40000000, 0x80000000, 0x1B000000, 0x36000000,
+                0x6C000000, 0xD8000000, 0xAB000000, 0x4D000000, 0x9A000000,
+                0x2F000000, 0x5E000000, 0xBC000000, 0x63000000, 0xC6000000,
+                0x97000000, 0x35000000, 0x6A000000, 0xD4000000, 0xB3000000,
+                0x7D000000, 0xFA000000, 0xEF000000, 0xC5000000, 0x91000000
+            );
+            $rcon = array_map('intval', $rcon);
+        }
 
         if (isset($this->kl['key']) && $this->key === $this->kl['key'] && $this->key_length === $this->kl['key_length'] && $this->block_size === $this->kl['block_size']) {
             // already expanded
@@ -511,7 +516,7 @@ class Rijndael extends Base
                 // on a 32-bit machine, it's 32-bits, and on a 64-bit machine, it's 64-bits. on a 32-bit machine,
                 // 0xFFFFFFFF << 8 == 0xFFFFFF00, but on a 64-bit machine, it equals 0xFFFFFFFF00. as such, doing 'and'
                 // with 0xFFFFFFFF (or 0xFFFFFF00) on a 32-bit machine is unnecessary, but on a 64-bit machine, it is.
-                $temp = (($temp << 8) & 0xFFFFFF00) | (($temp >> 24) & 0x000000FF); // rotWord
+                $temp = (($temp << 8) & intval(0xFFFFFF00)) | (($temp >> 24) & 0x000000FF); // rotWord
                 $temp = $this->_subWord($temp) ^ $rcon[$i / $this->Nk];
             } elseif ($this->Nk > 6 && $i % $this->Nk == 4) {
                 $temp = $this->_subWord($temp);
@@ -641,9 +646,9 @@ class Rijndael extends Base
             ));
 
             foreach ($t3 as $t3i) {
-                $t0[] = (($t3i << 24) & 0xFF000000) | (($t3i >>  8) & 0x00FFFFFF);
-                $t1[] = (($t3i << 16) & 0xFFFF0000) | (($t3i >> 16) & 0x0000FFFF);
-                $t2[] = (($t3i <<  8) & 0xFFFFFF00) | (($t3i >> 24) & 0x000000FF);
+                $t0[] = (($t3i << 24) & intval(0xFF000000)) | (($t3i >>  8) & 0x00FFFFFF);
+                $t1[] = (($t3i << 16) & intval(0xFFFF0000)) | (($t3i >> 16) & 0x0000FFFF);
+                $t2[] = (($t3i <<  8) & intval(0xFFFFFF00)) | (($t3i >> 24) & 0x000000FF);
             }
 
             $tables = array(
@@ -725,9 +730,9 @@ class Rijndael extends Base
             ));
 
             foreach ($dt3 as $dt3i) {
-                $dt0[] = (($dt3i << 24) & 0xFF000000) | (($dt3i >>  8) & 0x00FFFFFF);
-                $dt1[] = (($dt3i << 16) & 0xFFFF0000) | (($dt3i >> 16) & 0x0000FFFF);
-                $dt2[] = (($dt3i <<  8) & 0xFFFFFF00) | (($dt3i >> 24) & 0x000000FF);
+                $dt0[] = (($dt3i << 24) & intval(0xFF000000)) | (($dt3i >>  8) & 0x00FFFFFF);
+                $dt1[] = (($dt3i << 16) & intval(0xFFFF0000)) | (($dt3i >> 16) & 0x0000FFFF);
+                $dt2[] = (($dt3i <<  8) & intval(0xFFFFFF00)) | (($dt3i >> 24) & 0x000000FF);
             };
 
             $tables = array(
diff --git a/phpseclib/Crypt/Twofish.php b/phpseclib/Crypt/Twofish.php
index 70980a2f..458b871c 100644
--- a/phpseclib/Crypt/Twofish.php
+++ b/phpseclib/Crypt/Twofish.php
@@ -368,6 +368,42 @@ class Twofish extends Base
      */
     var $key_length = 16;
 
+    /**
+     * Default Constructor.
+     *
+     * Determines whether or not the mcrypt extension should be used.
+     *
+     * $mode could be:
+     *
+     * - CRYPT_MODE_ECB
+     *
+     * - CRYPT_MODE_CBC
+     *
+     * - CRYPT_MODE_CTR
+     *
+     * - CRYPT_MODE_CFB
+     *
+     * - CRYPT_MODE_OFB
+     *
+     * (or the alias constants of the chosen cipher, for example for AES: CRYPT_AES_MODE_ECB or CRYPT_AES_MODE_CBC ...)
+     *
+     * If not explicitly set, CRYPT_MODE_CBC will be used.
+     *
+     * @param int $mode
+     * @access public
+     */
+    function __construct($mode = CRYPT_MODE_CBC)
+    {
+        parent::__construct($mode);
+
+        $this->m0 = array_map('intval', $this->m0);
+        $this->m1 = array_map('intval', $this->m1);
+        $this->m2 = array_map('intval', $this->m2);
+        $this->m3 = array_map('intval', $this->m3);
+        $this->q0 = array_map('intval', $this->q0);
+        $this->q1 = array_map('intval', $this->q1);
+    }
+
     /**
      * Sets the key length.
      *