diff --git a/payment/uc_authorizenet/uc_authorizenet.install b/payment/uc_authorizenet/uc_authorizenet.install
index 7ac8d892..b1d41e0a 100644
--- a/payment/uc_authorizenet/uc_authorizenet.install
+++ b/payment/uc_authorizenet/uc_authorizenet.install
@@ -22,6 +22,12 @@ function uc_authorizenet_requirements($phase) {
     $requirements['uc_authorizenet_curl']['description'] = $t("Authorize.net requires the PHP <a href='!curl_url'>cURL</a> library.", array('!curl_url' => 'http://php.net/manual/en/curl.setup.php'));
   }
 
+  $hash = variable_get('uc_authnet_sha2_hash', FALSE);
+  if ($hash === FALSE) {
+    $requirements['uc_authorizenet_sha2_hash']['severity'] = REQUIREMENT_WARNING;
+    $requirements['uc_authorizenet_sha2_hash']['description'] = $t("Ubercart's Authorize.net Signature Key needs to be set in the payment <a href='!hash_url'>settings</a>.'", array('!hash_url' => url('admin/store/settings/payment/method/credit')));
+  }
+
   return $requirements;
 }
 
@@ -41,3 +47,11 @@ function uc_authorizenet_uninstall() {
 function uc_authorizenet_update_last_removed() {
   return 3;
 }
+
+/**
+ * Remove deprecated MD5 hash variable.
+ */
+function uc_authorizenet_update_7301(&$sandbox) {
+  variable_del('uc_authnet_md5_hash');
+}
+
diff --git a/payment/uc_authorizenet/uc_authorizenet.module b/payment/uc_authorizenet/uc_authorizenet.module
index 45eafdd1..4fd02b50 100644
--- a/payment/uc_authorizenet/uc_authorizenet.module
+++ b/payment/uc_authorizenet/uc_authorizenet.module
@@ -124,11 +124,11 @@ function uc_authorizenet_settings_form($form, &$form_state) {
     ),
     '#default_value' => variable_get('uc_authnet_arb_mode', 'disabled'),
   );
-  $form['arb_settings']['uc_authnet_md5_hash'] = array(
+  $form['arb_settings']['uc_authnet_sha2_hash'] = array(
     '#type' => 'textfield',
-    '#title' => t('MD5 Hash'),
-    '#description' => t('<b>Note:</b> You must first configure credit card encryption before setting this.<br />Enter the value here you entered in your Auth.Net account settings.'),
-    '#default_value' => $login_data['md5_hash'],
+    '#title' => t('Signature Key'),
+    '#description' => t('<b>Note:</b> You must first configure credit card encryption before setting this.<br />Enter the value here you entered in your Auth.Net account settings.<br/>To generate a new hash'),
+    '#default_value' => $login_data['sha2_hash'],
     '#access' => user_access('administer credit cards'),
   );
   $form['arb_settings']['uc_authnet_report_arb_post'] = array(
@@ -181,9 +181,9 @@ function uc_authorizenet_payment_gateway_settings_submit($form, &$form_state) {
     // Setup our encryption object.
     $crypt = new UbercartEncryption();
 
-    // Encrypt the Login ID, Transaction key, and MD5 Hash.
-    if (!empty($form_state['values']['uc_authnet_md5_hash'])) {
-      variable_set('uc_authnet_md5_hash', $crypt->encrypt($key, $form_state['values']['uc_authnet_md5_hash']));
+    // Encrypt the Login ID, Transaction key, and SHA256 Hash.
+    if (!empty($form_state['values']['uc_authnet_sha2_hash'])) {
+      variable_set('uc_authnet_sha2_hash', $crypt->encrypt($key, $form_state['values']['uc_authnet_sha2_hash']));
     }
 
     // Store any errors.
@@ -965,16 +965,16 @@ function _uc_authorizenet_login_data() {
     return $data;
   }
 
-  $md5_hash = variable_get('uc_authnet_md5_hash', '');
+  $sha2_hash = variable_get('uc_authnet_sha2_hash', '');
 
   // If CC encryption has been configured properly.
   if ($key = uc_credit_encryption_key()) {
     // Setup our encryption object.
     $crypt = new UbercartEncryption();
 
-    // Decrypt the MD5 Hash.
-    if (!empty($md5_hash)) {
-      $md5_hash = $crypt->decrypt($key, $md5_hash);
+    // Decrypt the SHA256 Hash.
+    if (!empty($sha2_hash)) {
+      $sha2_hash = $crypt->decrypt($key, $sha2_hash);
     }
 
     // Store any errors.
@@ -982,8 +982,22 @@ function _uc_authorizenet_login_data() {
   }
 
   $data = array(
-    'md5_hash' => $md5_hash,
+    'sha2_hash' => $sha2_hash,
   );
 
   return $data;
 }
+
+/**
+ * Implements hook_store_status().
+ */
+function uc_authorizenet_uc_store_status() {
+  if (variable_get('uc_authnet_sha2_hash', FALSE) === FALSE) {
+    $statuses[] = array(
+      'status' => 'warning',
+      'title' => t('Authorize.net Signature'),
+      'desc' => t('Authorize.net Signature Key should be configured to ensure there are no interruptions in functionality.'),
+    );
+  }
+  return $statuses;
+}
diff --git a/payment/uc_authorizenet/uc_authorizenet.pages.inc b/payment/uc_authorizenet/uc_authorizenet.pages.inc
index 9a7fe556..5196f63a 100644
--- a/payment/uc_authorizenet/uc_authorizenet.pages.inc
+++ b/payment/uc_authorizenet/uc_authorizenet.pages.inc
@@ -31,10 +31,10 @@ function uc_authorizenet_silent_post() {
   if ($arb) {
 
     // Compare our expected MD5 Hash against what was received.
-    $md5 = strtoupper(md5($login_data['md5_hash'] . $_POST['x_trans_id'] . $_POST['x_amount']));
+    $sha2 = strtoupper(hash('sha256', $login_data['sha2_hash'] . $_POST['x_trans_id'] . $_POST['x_amount']));
 
     // Post an error message if the MD5 hash does not validate.
-    if ($_POST['x_MD5_Hash'] != $md5) {
+    if ($_POST['x_SHA2_Hash'] != $sha2) {
       watchdog('uc_authorizenet', 'Invalid ARB payment notification received.', array(), WATCHDOG_ERROR);
     }
     // Otherwise, let other modules act on the data.