diff --git a/core/oecaptcha.php b/core/oecaptcha.php
index 88ef8b8..d086d25 100644
--- a/core/oecaptcha.php
+++ b/core/oecaptcha.php
@@ -110,10 +110,14 @@ class oeCaptcha extends oxSuperCfg
      */
     public function getImageUrl()
     {
-        $url = $this->getConfig()->getCurrentShopUrl() . 'modules/oe/captcha/core/utils/verificationimg.php?e_mac=';
-        $key = $this->getConfig()->getConfigParam('oecaptchakey');
-        $key = empty($key) ? null : $key;
-        $url .= oxRegistry::getUtils()->strMan($this->getText(), $key);
+        $config = \OxidEsales\Eshop\Core\Registry::getConfig();
+        $url = $config->getCurrentShopUrl() . 'modules/oe/captcha/core/utils/verificationimg.php?e_mac=';
+        $key = $config->getConfigParam('oecaptchakey');
+
+        $key = $key ? $key : $config->getConfigParam('sConfigKey');
+
+        $encryptor = new \OxidEsales\Eshop\Core\Encryptor();
+        $url .= $encryptor->encrypt($this->getText(), $key);
 
         return $url;
     }
diff --git a/tests/unit/core/oecaptchaTest.php b/tests/unit/core/oecaptchaTest.php
index fb7bd44..12f2b30 100644
--- a/tests/unit/core/oecaptchaTest.php
+++ b/tests/unit/core/oecaptchaTest.php
@@ -78,7 +78,7 @@ class Unit_Core_oecaptchaTest extends CaptchaTestCase
      */
     public function testGetImageUrl()
     {
-        $this->setConfigParam('oecaptchakey', 'someTestCaptchaKey');
+        $this->getConfig()->setConfigParam("oecaptchakey", 'someTestCaptchaKey');
         $this->captcha->setNonPublicVar('text', 'test1');
         $expected = $this->getConfig()->getShopUrl() . 'modules/oe/captcha/core/utils/verificationimg.php?e_mac=ox_MAsbCBYgVBoQ';
 
@@ -90,7 +90,7 @@ class Unit_Core_oecaptchaTest extends CaptchaTestCase
      */
     public function testGetImageUrlFallbackKey()
     {
-        $this->setConfigParam('oecaptchakey', '');
+        $this->getConfig()->setConfigParam("oecaptchakey", '');
         $this->captcha->setNonPublicVar('text', 'test1');
 
         $expected = $this->getConfig()->getShopUrl() . 'modules/oe/captcha/core/utils/verificationimg.php?e_mac=ox_MB4FUUYlYlld';