diff --git a/etc/adminhtml/system.xml b/etc/adminhtml/system.xml
index cb77751..c095153 100644
--- a/etc/adminhtml/system.xml
+++ b/etc/adminhtml/system.xml
@@ -10,11 +10,13 @@
             <resource>Thai_S3::config_s3</resource>
             <group id="general" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>General</label>
-                <field id="access_key" type="text" showInDefault="1" showInWebsite="1" showInStore="1">
+                <field id="access_key" type="obscure" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                     <label>Access Key</label>
+                    <backend_model>Magento\Config\Model\Config\Backend\Encrypted</backend_model>
                 </field>
-                <field id="secret_key" type="text" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1">
+                <field id="secret_key" type="obscure" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1">
                     <label>Secret Key</label>
+                    <backend_model>Magento\Config\Model\Config\Backend\Encrypted</backend_model>
                 </field>
                 <field id="bucket" type="text" sortOrder="30" showInDefault="1" showInWebsite="1" showInStore="1">
                     <label>Bucket</label>
diff --git a/etc/config.xml b/etc/config.xml
index a91f750..daf9761 100644
--- a/etc/config.xml
+++ b/etc/config.xml
@@ -2,6 +2,12 @@
 <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
     <default>
         <system>
+            <thai_s3>
+                <general>
+                    <access_key backend_model="Magento\Config\Model\Config\Backend\Encrypted" />
+                    <secret_key backend_model="Magento\Config\Model\Config\Backend\Encrypted" />
+                </general>
+            </thai_s3>
             <media_storage_configuration>
                 <allowed_resources>
                     <attribute_image_folder>attribute</attribute_image_folder>
diff --git a/etc/di.xml b/etc/di.xml
index b0f741d..2b8dcd9 100644
--- a/etc/di.xml
+++ b/etc/di.xml
@@ -52,4 +52,12 @@
     <type name="Magento\Captcha\Model\DefaultModel">
         <plugin name="thai_s3_model_captcha_defaultmodel_plugin" type="Thai\S3\Model\Captcha\DefaultModel\Plugin" />
     </type>
+    <type name="Magento\Config\Model\Config\TypePool">
+        <arguments>
+            <argument name="sensitive" xsi:type="array">
+                <item name="thai_s3/general/access_key" xsi:type="string">1</item>
+                <item name="thai_s3/general/secret_key" xsi:type="string">1</item>
+            </argument>
+        </arguments>
+    </type>
 </config>