diff --git a/lib/RandomLib/Source/ExecTime.php b/lib/RandomLib/Source/ExecTime.php
new file mode 100644
index 0000000..ee390a5
--- /dev/null
+++ b/lib/RandomLib/Source/ExecTime.php
@@ -0,0 +1,129 @@
+<?php
+/**
+ * The MTRand Random Number Source
+ *
+ * This source generates low strength random numbers by using the internal
+ * mt_rand() function.  By itself it is quite weak.  However when combined with
+ * other sources it does provide significant benefit.
+ *
+ * PHP version 5.3
+ *
+ * @category   PHPCryptLib
+ * @package    Random
+ * @subpackage Source
+ * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @copyright  2011 The Authors
+ * @license    http://www.opensource.org/licenses/mit-license.html  MIT License
+ * @version    Build @@version@@
+ */
+
+/*
+* Author:
+* George Argyros <argyros.george@gmail.com>
+*
+* Copyright (c) 2012, George Argyros
+* All rights reserved.
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions are met:
+* * Redistributions of source code must retain the above copyright
+* notice, this list of conditions and the following disclaimer.
+* * Redistributions in binary form must reproduce the above copyright
+* notice, this list of conditions and the following disclaimer in the
+* documentation and/or other materials provided with the distribution.
+* * Neither the name of the <organization> nor the
+* names of its contributors may be used to endorse or promote products
+* derived from this software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+* DISCLAIMED. IN NO EVENT SHALL GEORGE ARGYROS BE LIABLE FOR ANY
+* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*
+*
+*
+* The function is providing, at least at the systems tested :),
+* $len bytes of entropy under any PHP installation or operating system.
+* The execution time should be at most 10-20 ms in any system.
+*/
+
+namespace RandomLib\Source;
+
+use SecurityLib\Strength;
+
+/**
+ * The ExecTime Random Number Source
+ *
+ * This source generates low strength random numbers by measuring the execution
+ * time to perform a sequence of SHA1 computations seeded by mt_rand().
+ *
+ * @category   PHPCryptLib
+ * @package    Random
+ * @subpackage Source
+ * @author     Anthony Ferrara <ircmaxell@ircmaxell.com>
+ * @codeCoverageIgnore
+ */
+class ExecTime implements \RandomLib\Source {
+
+    /**
+     * Return an instance of Strength indicating the strength of the source
+     *
+     * @return Strength An instance of one of the strength classes
+     */
+    public static function getStrength() {
+        return new Strength(Strength::LOW);
+    }
+
+    /**
+     * Generate a random string of the specified size
+     *
+     * @param int $size The size of the requested random string
+     *
+     * @return string A string of the requested size
+     */
+    public function generate($size) {
+        $result = '';
+        $entropy = '';
+        $msec_per_round = 400;
+        $bits_per_round = 2;
+        $total = $size;
+        $bytes = 0;
+        $hash_length = 20;
+        $rounds = 0;
+        while (strlen($result) < $size) {
+            $bytes = ($total > $hash_length)? $hash_length : $total;
+            $total -= $bytes;
+            for ($i=1; $i < 3; $i++) {
+                $t1 = microtime(true);
+                $seed = mt_rand();
+                for ($j=1; $j < 50; $j++) { 
+                    $seed = sha1($seed);
+                }
+                $t2 = microtime(true);
+                $entropy .= $t1 . $t2;
+            }
+            $rounds = (int) ($msec_per_round * 50 / (int) (($t2 - $t1) * 1000000));
+            $iter = $bytes * (int) (ceil(8 / $bits_per_round));
+            for ($i = 0; $i < $iter; $i ++)
+            {
+                $t1 = microtime();
+                $seed = sha1(mt_rand());
+                for ($j = 0; $j < $rounds; $j++)
+                {
+                   $seed = sha1($seed);
+                }
+                $t2 = microtime();
+                $entropy .= $t1 . $t2;
+            }
+            $result .= sha1($entropy, true);
+        }
+        return substr($result, 0, $size);
+    }
+
+}
diff --git a/test/Unit/RandomLib/Source/ExecTimeTest.php b/test/Unit/RandomLib/Source/ExecTimeTest.php
new file mode 100644
index 0000000..d71e9c1
--- /dev/null
+++ b/test/Unit/RandomLib/Source/ExecTimeTest.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace RandomLib\Source;
+
+use SecurityLib\Strength;
+
+
+
+class ExecTimeTest extends \PHPUnit_Framework_TestCase {
+
+    public static function provideGenerate() {
+        $data = array();
+        for ($i = 0; $i < 10; $i += 5) {
+            $not = $i > 0 ? str_repeat(chr(0), $i) : chr(0);
+            $data[] = array($i, $not);
+        }
+        return $data;
+    }
+
+    /**
+     */
+    public function testGetStrength() {
+        $strength = new Strength(Strength::LOW);
+        $actual = ExecTime::getStrength();
+        $this->assertEquals($actual, $strength);
+    }
+
+    /**
+     * @dataProvider provideGenerate
+     */
+    public function testGenerate($length, $not) {
+        $rand = new ExecTime;
+        $stub = $rand->generate($length);
+        $this->assertEquals($length, strlen($stub));
+        $this->assertNotEquals($not, $stub);
+    }
+
+}