diff --git a/phpseclib/Crypt/Base.php b/phpseclib/Crypt/Base.php
index c14cbf3e..51d68026 100644
--- a/phpseclib/Crypt/Base.php
+++ b/phpseclib/Crypt/Base.php
@@ -37,6 +37,8 @@
 namespace phpseclib\Crypt;
 
 use phpseclib\Crypt\Hash;
+use phpseclib\Exception\InvalidInputException;
+use phpseclib\Exception\KeyGenerationException;
 
 /**
  * Base Class for all \phpseclib\Crypt\* cipher classes
@@ -579,8 +581,7 @@ abstract class Base
                         $hashObj = new Hash();
                         $hashObj->setHash($hash);
                         if ($dkLen > $hashObj->getLength()) {
-                            user_error('Derived key too long');
-                            return false;
+                            throw new KeyGenerationException('Derived key too long');
                         }
                         $t = $password . $salt;
                         for ($i = 0; $i < $count; ++$i) {
@@ -1779,8 +1780,7 @@ abstract class Base
             if ($length % $this->block_size == 0) {
                 return $text;
             } else {
-                user_error("The plaintext's length ($length) is not a multiple of the block size ({$this->block_size})");
-                $this->padding = true;
+                throw new InvalidInputException("The plaintext's length ($length) is not a multiple of the block size ({$this->block_size}). Try enabling padding.");
             }
         }
 
@@ -1809,7 +1809,7 @@ abstract class Base
         $length = ord($text[strlen($text) - 1]);
 
         if (!$length || $length > $this->block_size) {
-            return false;
+            throw new InvalidInputException("The ciphertext has an invalid padding length ($length) compared to the block size ({$this->block_size})");
         }
 
         return substr($text, 0, -$length);
diff --git a/phpseclib/Exception/InvalidInputException.php b/phpseclib/Exception/InvalidInputException.php
new file mode 100644
index 00000000..511f62b6
--- /dev/null
+++ b/phpseclib/Exception/InvalidInputException.php
@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * InvalidInputException
+ *
+ * PHP version 5
+ *
+ * @category  Exception
+ * @package   InvalidInputException
+ * @copyright 2015 Jim Wigginton
+ * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
+ * @link      http://phpseclib.sourceforge.net
+ */
+
+namespace phpseclib\Exception;
+
+class InvalidInputException extends \Exception
+{
+}
\ No newline at end of file
diff --git a/phpseclib/Exception/KeyGenerationException.php b/phpseclib/Exception/KeyGenerationException.php
new file mode 100644
index 00000000..962d830e
--- /dev/null
+++ b/phpseclib/Exception/KeyGenerationException.php
@@ -0,0 +1,19 @@
+<?php
+
+/**
+ * KeyGenerationException
+ *
+ * PHP version 5
+ *
+ * @category  Exception
+ * @package   KeyGenerationException
+ * @copyright 2015 Jim Wigginton
+ * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
+ * @link      http://phpseclib.sourceforge.net
+ */
+
+namespace phpseclib\Exception;
+
+class KeyGenerationException extends \Exception
+{
+}
\ No newline at end of file