diff --git a/config/install/cas.settings.yml b/config/install/cas.settings.yml
index 963d528..39b51e0 100644
--- a/config/install/cas.settings.yml
+++ b/config/install/cas.settings.yml
@@ -3,6 +3,7 @@ server:
   hostname: ''
   port: 443
   path: '/'
+  verify: 0
   cert: ''
 
 gateway:
diff --git a/config/schema/cas.schema.yml b/config/schema/cas.schema.yml
index af670a7..d6005c1 100644
--- a/config/schema/cas.schema.yml
+++ b/config/schema/cas.schema.yml
@@ -20,6 +20,9 @@ cas.settings:
         path:
           type: string
           label: 'Path'
+        verify:
+          type: integer
+          label: 'SSL Verification Method'
         cert:
           type: string
           label: 'PEM Cert path'
diff --git a/src/Form/CasSettings.php b/src/Form/CasSettings.php
index d1a4d04..9b2a620 100755
--- a/src/Form/CasSettings.php
+++ b/src/Form/CasSettings.php
@@ -103,10 +103,21 @@ class CasSettings extends ConfigFormBase {
       '#size' => 30,
       '#default_value' => $config->get('server.path'),
     );
+    $form['server']['verify'] = array(
+      '#type' => 'radios',
+      '#title' => 'SSL Verification Method',
+      '#description' => $this->t('The SSL verification behavior. It is dangerous to not verify the CA of the CAS server.'),
+      '#options' => array(
+        CasHelper::CA_DEFAULT => $this->t('Use your web server\'s default certificates.'),
+        CasHelper::CA_CUSTOM => $this->t('Specify a custom SSL certificate in the local filesystem. Use the field below to provide path.'),
+        CasHelper::CA_NONE => $this->t('Do not verify CAS server. THIS SHOULD NOT BE USED ON PRODUCTION SITES!'),
+      ),
+      '#default_value' => $config->get('server.verify'),
+    );
     $form['server']['cert'] = array(
       '#type' => 'textfield',
       '#title' => $this->t('Certificate Authority PEM Certificate'),
-      '#description' => $this->t('The PEM certificate of the Certificate Authority that issued the certificate of the CAS server. If omitted, the certificate authority will not be verified.'),
+      '#description' => $this->t('The PEM certificate of the Certificate Authority that issued the certificate of the CAS server, used only with the custom certificate option above. If omitted, the certificate authority will not be verified.'),
       '#default_value' => $config->get('server.cert'),
     );
 
@@ -292,6 +303,7 @@ class CasSettings extends ConfigFormBase {
       ->set('server.hostname', $server_data['hostname'])
       ->set('server.port', $server_data['port'])
       ->set('server.path', $server_data['path'])
+      ->set('server.verify', $server_data['verify'])
       ->set('server.cert', $server_data['cert']);
 
     $condition_values = (new FormState())
diff --git a/src/Service/CasHelper.php b/src/Service/CasHelper.php
index a2ce92a..d4b00d0 100644
--- a/src/Service/CasHelper.php
+++ b/src/Service/CasHelper.php
@@ -13,6 +13,27 @@ use Drupal\Core\Logger\RfcLogLevel;
 
 class CasHelper {
 
+  /** 
+   * SSL configuration to use the system's CA bundle to verify CAS server.
+   *
+   * @var int
+   */
+  const CA_DEFAULT = 0;
+
+  /** 
+   * SSL configuration to use provided file to verify CAS server.
+   *
+   * @var int
+   */
+  const CA_CUSTOM = 1;
+
+  /**
+   * SSL Configuration to not verify CAS server.
+   *
+   * @var int
+   */
+  const CA_NONE = 2;
+
   /**
    * Gateway configuration to never check preemptively to see if the user is
    * logged in.
@@ -188,6 +209,16 @@ class CasHelper {
   }
 
   /**
+   * Return the SSL verification method.
+   *
+   * @return int
+   *   The verification method.
+   */
+  public function getSslVerificationMethod() {
+    return $this->settings->get('server.verify');
+  }
+
+  /**
    * Return CA PEM file path.
    *
    * @return mixed|null
diff --git a/src/Service/CasValidator.php b/src/Service/CasValidator.php
index a082a28..cf262ab 100644
--- a/src/Service/CasValidator.php
+++ b/src/Service/CasValidator.php
@@ -54,12 +54,29 @@ class CasValidator {
       $validate_url = $this->casHelper->getServerValidateUrl($ticket, $service_params);
       $this->casHelper->log("Trying to validate against $validate_url");
       $options = array();
-      $cert = $this->casHelper->getCertificateAuthorityPem();
-      if (!empty($cert)) {
-        $options['verify'] = $cert;
-      }
-      else {
-        $options['verify'] = FALSE;
+      $verify = $this->casHelper->getSslVerificationMethod();
+      switch ($verify) {
+        case CasHelper::CA_DEFAULT:
+          $options['verify'] = TRUE;
+          break;
+        
+        case CasHelper::CA_CUSTOM:
+          $cert = $this->casHelper->getCertificateAuthorityPem();
+          if (!empty($cert)) {
+            $options['verify'] = $cert;
+          }
+          else {
+            $options['verify'] = FALSE;
+          }
+          break;
+
+        case CasHelper:: CA_NONE:
+          $options['verify'] = FALSE;
+          break;
+
+        default:
+          $options['verify'] = TRUE;
+
       }
       $response = $this->httpClient->get($validate_url, $options);
       $response_data = $response->getBody()->__toString();
diff --git a/tests/src/Unit/Service/CasHelperTest.php b/tests/src/Unit/Service/CasHelperTest.php
index 693b0dd..bd2075d 100644
--- a/tests/src/Unit/Service/CasHelperTest.php
+++ b/tests/src/Unit/Service/CasHelperTest.php
@@ -368,6 +368,24 @@ class CasHelperTest extends UnitTestCase {
   }
 
   /**
+   * Test getting the SSL verification method.
+   *
+   * @covers ::getSslVerificationMethod
+   */
+  public function testGetSslVerificationMethod() {
+    $config_factory = $this->getConfigFactoryStub(array(
+      'cas.settings' => array(
+        'server.hostname' => 'example.com',
+        'server.port' => 443,
+        'server.path' => '/cas',
+        'server.verify' => 17,
+      ),
+    ));
+    $cas_helper = new CasHelper($config_factory, $this->urlGenerator, $this->connection, $this->loggerFactory);
+    $this->assertEquals(17, $cas_helper->getSslVerificationMethod());
+  }
+
+  /**
    * Test getting the CA PEM file.
    *
    * @covers ::getCertificateAuthorityPem
diff --git a/tests/src/Unit/Service/CasValidatorTest.php b/tests/src/Unit/Service/CasValidatorTest.php
index a957592..162f173 100644
--- a/tests/src/Unit/Service/CasValidatorTest.php
+++ b/tests/src/Unit/Service/CasValidatorTest.php
@@ -49,7 +49,7 @@ class CasValidatorTest extends UnitTestCase {
                       ->getMock();
     $casValidator = new CasValidator($httpClient, $casHelper);
 
-    $casHelper->expects($this->once())
+    $casHelper->expects($this->any())
               ->method('getCertificateAuthorityPem')
               ->will($this->returnValue('foo'));