diff --git a/composer.json b/composer.json
index 58e80fa..7650d8a 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
         }
     },
     "require": {
-        "php": ">=5.3.3",
+        "php": ">=5.3.23",
         "zendframework/zend-stdlib": "self.version"
     },
     "require-dev": {
diff --git a/src/Adapter/Http.php b/src/Adapter/Http.php
index 6360430..2cc3db5 100644
--- a/src/Adapter/Http.php
+++ b/src/Adapter/Http.php
@@ -336,11 +336,11 @@ public function authenticate()
 
         $headers = $this->request->getHeaders();
         if (!$headers->has($getHeader)) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
         $authHeader = $headers->get($getHeader)->getFieldValue();
         if (!$authHeader) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
 
         list($clientScheme) = explode(' ', $authHeader);
@@ -360,7 +360,7 @@ public function authenticate()
         // client sent a scheme that is not the one required
         if (!in_array($clientScheme, $this->acceptSchemes)) {
             // challenge again the client
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
 
         switch ($clientScheme) {
@@ -377,6 +377,23 @@ public function authenticate()
         return $result;
     }
 
+    /**
+     * @deprecated
+     * @see Http::challengeClient()
+     * @return Authentication\Result Always returns a non-identity Auth result
+     */
+    protected function _challengeClient()
+    {
+        trigger_error(sprintf(
+            'The method "%s" is deprecated and will be removed in the future; '
+            . 'please use the public method "%s::challengeClient()" instead',
+            __METHOD__,
+            __CLASS__
+        ), E_USER_DEPRECATED);
+
+        return $this->challengeClient();
+    }
+
     /**
      * Challenge Client
      *
@@ -385,7 +402,7 @@ public function authenticate()
      *
      * @return Authentication\Result Always returns a non-identity Auth result
      */
-    protected function _challengeClient()
+    public function challengeClient()
     {
         if ($this->imaProxy) {
             $statusCode = 407;
@@ -474,12 +491,12 @@ protected function _basicAuth($header)
         // implementation does. If invalid credentials are detected,
         // re-challenge the client.
         if (!ctype_print($auth)) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
         // Fix for ZF-1515: Now re-challenges on empty username or password
         $creds = array_filter(explode(':', $auth));
         if (count($creds) != 2) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
 
         $result = $this->basicResolver->resolve($creds[0], $this->realm, $creds[1]);
@@ -498,7 +515,7 @@ protected function _basicAuth($header)
             return new Authentication\Result(Authentication\Result::SUCCESS, $result);
         }
 
-        return $this->_challengeClient();
+        return $this->challengeClient();
     }
 
     /**
@@ -530,17 +547,17 @@ protected function _digestAuth($header)
         // See ZF-1052. This code was a bit too unforgiving of invalid
         // usernames. Now, if the username is bad, we re-challenge the client.
         if ('::invalid::' == $data['username']) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
 
         // Verify that the client sent back the same nonce
         if ($this->_calcNonce() != $data['nonce']) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
         // The opaque value is also required to match, but of course IE doesn't
         // play ball.
         if (!$this->ieNoOpaque && $this->_calcOpaque() != $data['opaque']) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
 
         // Look up the user's password hash. If not found, deny access.
@@ -549,7 +566,7 @@ protected function _digestAuth($header)
         // to be recreatable with the current settings of this object.
         $ha1 = $this->digestResolver->resolve($data['username'], $data['realm']);
         if ($ha1 === false) {
-            return $this->_challengeClient();
+            return $this->challengeClient();
         }
 
         // If MD5-sess is used, a1 value is made of the user's password
@@ -588,7 +605,7 @@ protected function _digestAuth($header)
             return new Authentication\Result(Authentication\Result::SUCCESS, $identity);
         }
 
-        return $this->_challengeClient();
+        return $this->challengeClient();
     }
 
     /**
diff --git a/src/AuthenticationService.php b/src/AuthenticationService.php
index 212747d..76a26d3 100644
--- a/src/AuthenticationService.php
+++ b/src/AuthenticationService.php
@@ -9,7 +9,7 @@
 
 namespace Zend\Authentication;
 
-class AuthenticationService
+class AuthenticationService implements AuthenticationServiceInterface
 {
     /**
      * Persistent storage handler
diff --git a/src/AuthenticationServiceInterface.php b/src/AuthenticationServiceInterface.php
new file mode 100644
index 0000000..fcf74ea
--- /dev/null
+++ b/src/AuthenticationServiceInterface.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ */
+
+namespace Zend\Authentication;
+
+/**
+ * Provides an API for authentication and identity management
+ */
+interface AuthenticationServiceInterface
+{
+    /**
+     * Authenticates and provides an authentication result
+     *
+     * @return Result
+     */
+    public function authenticate();
+
+    /**
+     * Returns true if and only if an identity is available
+     *
+     * @return bool
+     */
+    public function hasIdentity();
+
+    /**
+     * Returns the authenticated identity or null if no identity is available
+     *
+     * @return mixed|null
+     */
+    public function getIdentity();
+
+    /**
+     * Clears the identity
+     *
+     * @return void
+     */
+    public function clearIdentity();
+}
diff --git a/test/Adapter/DbTable/CallbackCheckAdapterTest.php b/test/Adapter/DbTable/CallbackCheckAdapterTest.php
index abea0d6..d23c3a7 100644
--- a/test/Adapter/DbTable/CallbackCheckAdapterTest.php
+++ b/test/Adapter/DbTable/CallbackCheckAdapterTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/DbTable/CredentialTreatmentAdapterTest.php b/test/Adapter/DbTable/CredentialTreatmentAdapterTest.php
index 048d13a..8efab92 100644
--- a/test/Adapter/DbTable/CredentialTreatmentAdapterTest.php
+++ b/test/Adapter/DbTable/CredentialTreatmentAdapterTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/DbTableTest.php b/test/Adapter/DbTableTest.php
index 0c8985f..44154ef 100644
--- a/test/Adapter/DbTableTest.php
+++ b/test/Adapter/DbTableTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/DigestTest.php b/test/Adapter/DigestTest.php
index 2882e1b..2ff12ee 100644
--- a/test/Adapter/DigestTest.php
+++ b/test/Adapter/DigestTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/Http/ApacheResolverTest.php b/test/Adapter/Http/ApacheResolverTest.php
index d07e05c..56d3e83 100644
--- a/test/Adapter/Http/ApacheResolverTest.php
+++ b/test/Adapter/Http/ApacheResolverTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/Http/AuthTest.php b/test/Adapter/Http/AuthTest.php
index 7072827..3763293 100644
--- a/test/Adapter/Http/AuthTest.php
+++ b/test/Adapter/Http/AuthTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/Http/FileResolverTest.php b/test/Adapter/Http/FileResolverTest.php
index 5c1bf9b..6034e66 100644
--- a/test/Adapter/Http/FileResolverTest.php
+++ b/test/Adapter/Http/FileResolverTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/Http/ObjectTest.php b/test/Adapter/Http/ObjectTest.php
index 6d4c9a0..0cb7082 100644
--- a/test/Adapter/Http/ObjectTest.php
+++ b/test/Adapter/Http/ObjectTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/Http/ProxyTest.php b/test/Adapter/Http/ProxyTest.php
index 5db5bee..af9f407 100644
--- a/test/Adapter/Http/ProxyTest.php
+++ b/test/Adapter/Http/ProxyTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
@@ -94,7 +94,7 @@ public function setUp()
 
     public function testBasicChallenge()
     {
-        // Trying to authenticate without sending an Proxy-Authorization header
+        // Trying to authenticate without sending a Proxy-Authorization header
         // should result in a 407 reply with a Proxy-Authenticate header, and a
         // false result.
 
@@ -110,7 +110,7 @@ public function testBasicChallenge()
 
     public function testDigestChallenge()
     {
-        // Trying to authenticate without sending an Proxy-Authorization header
+        // Trying to authenticate without sending a Proxy-Authorization header
         // should result in a 407 reply with a Proxy-Authenticate header, and a
         // false result.
 
@@ -123,7 +123,7 @@ public function testDigestChallenge()
 
     public function testBothChallenges()
     {
-        // Trying to authenticate without sending an Proxy-Authorization header
+        // Trying to authenticate without sending a Proxy-Authorization header
         // should result in a 407 reply with at least one Proxy-Authenticate
         // header, and a false result.
 
diff --git a/test/Adapter/Http/TestAsset/BasicAuthObjectResolver.php b/test/Adapter/Http/TestAsset/BasicAuthObjectResolver.php
index bd826f9..2084209 100644
--- a/test/Adapter/Http/TestAsset/BasicAuthObjectResolver.php
+++ b/test/Adapter/Http/TestAsset/BasicAuthObjectResolver.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/HttpTest.php b/test/Adapter/HttpTest.php
new file mode 100644
index 0000000..1b5ba91
--- /dev/null
+++ b/test/Adapter/HttpTest.php
@@ -0,0 +1,52 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @link      http://github.com/zendframework/zf2 for the canonical source repository
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   http://framework.zend.com/license/new-bsd New BSD License
+ * @package   Zend_Authentication
+ */
+
+namespace ZendTest\Authentication\Adapter;
+
+use Zend\Authentication\Adapter;
+
+class HttpTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * @var Wrapper
+     */
+    protected $_wrapper;
+
+    public function setUp()
+    {
+        $config = array(
+            'accept_schemes' => 'basic',
+            'realm'          => 'testing',
+        );
+
+        $this->_wrapper = new Wrapper($config);
+    }
+
+    public function tearDown()
+    {
+        unset($this->_wrapper);
+    }
+
+    /**
+     * @expectedException PHPUnit_Framework_Error_Deprecated
+     */
+    public function testProtectedMethodChallengeClientTriggersErrorDeprecated()
+    {
+        $this->_wrapper->_challengeClient();
+    }
+}
+
+class Wrapper extends Adapter\Http
+{
+    public function __call($method, $args)
+    {
+        return call_user_func_array(array($this, $method), $args);
+    }
+}
diff --git a/test/Adapter/Ldap/OfflineTest.php b/test/Adapter/Ldap/OfflineTest.php
index 9573f04..b3386c8 100644
--- a/test/Adapter/Ldap/OfflineTest.php
+++ b/test/Adapter/Ldap/OfflineTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/Ldap/OnlineTest.php b/test/Adapter/Ldap/OnlineTest.php
index dc3d47f..e7ef40c 100644
--- a/test/Adapter/Ldap/OnlineTest.php
+++ b/test/Adapter/Ldap/OnlineTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Adapter/TestAsset/OpenIdResponseHelper.php b/test/Adapter/TestAsset/OpenIdResponseHelper.php
index e97a8d1..cc6adca 100644
--- a/test/Adapter/TestAsset/OpenIdResponseHelper.php
+++ b/test/Adapter/TestAsset/OpenIdResponseHelper.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/AuthenticationServiceTest.php b/test/AuthenticationServiceTest.php
index fdf0696..f4253d5 100644
--- a/test/AuthenticationServiceTest.php
+++ b/test/AuthenticationServiceTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Storage/ChainTest.php b/test/Storage/ChainTest.php
index 783da9d..3fa2c15 100644
--- a/test/Storage/ChainTest.php
+++ b/test/Storage/ChainTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/TestAsset/SuccessAdapter.php b/test/TestAsset/SuccessAdapter.php
index b1ecc3a..b7c0f2a 100644
--- a/test/TestAsset/SuccessAdapter.php
+++ b/test/TestAsset/SuccessAdapter.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */
 
diff --git a/test/Validator/AuthenticationTest.php b/test/Validator/AuthenticationTest.php
index 211d2b5..c21132a 100644
--- a/test/Validator/AuthenticationTest.php
+++ b/test/Validator/AuthenticationTest.php
@@ -3,7 +3,7 @@
  * Zend Framework (http://framework.zend.com/)
  *
  * @link      http://github.com/zendframework/zf2 for the canonical source repository
- * @copyright Copyright (c) 2005-2013 Zend Technologies USA Inc. (http://www.zend.com)
+ * @copyright Copyright (c) 2005-2014 Zend Technologies USA Inc. (http://www.zend.com)
  * @license   http://framework.zend.com/license/new-bsd New BSD License
  */