diff --git a/.gitignore b/.gitignore
index 4ef7f72..3e9ecf8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -258,3 +258,4 @@ xml/
 ltapi/
 ltambz/
 hashChanges.yaml
+.piopm
diff --git a/arduino/libretuya/libraries/MD5/MD5.h b/arduino/libretuya/libraries/MD5/MD5.h
new file mode 100644
index 0000000..ea0c98f
--- /dev/null
+++ b/arduino/libretuya/libraries/MD5/MD5.h
@@ -0,0 +1,27 @@
+/* Copyright (c) Kuba Szczodrzyński 2022-06-03. */
+
+#pragma once
+
+#include <MD5Impl.h>
+
+// available built-in implementations
+#if LT_MD5_USE_POLARSSL
+#include "MD5PolarSSLImpl.h"
+#endif
+
+// common API
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef LT_MD5_CTX_T
+#define LT_MD5_CTX_T void
+#endif
+
+void MD5Init(LT_MD5_CTX_T *context);
+void MD5Update(LT_MD5_CTX_T *context, const unsigned char *buf, unsigned len);
+void MD5Final(unsigned char digest[16], LT_MD5_CTX_T *context);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/arduino/libretuya/libraries/MD5/MD5PolarSSLImpl.cpp b/arduino/libretuya/libraries/MD5/MD5PolarSSLImpl.cpp
new file mode 100644
index 0000000..f03ddb7
--- /dev/null
+++ b/arduino/libretuya/libraries/MD5/MD5PolarSSLImpl.cpp
@@ -0,0 +1,29 @@
+/* Copyright (c) Kuba Szczodrzyński 2022-06-03. */
+
+// check if impl defines LT_MD5_USE_POLARSSL
+extern "C" {
+#include <MD5Impl.h>
+}
+
+#if LT_MD5_USE_POLARSSL
+
+#include "MD5PolarSSLImpl.h"
+
+extern "C" {
+
+void MD5Init(LT_MD5_CTX_T *context) {
+	md5_init(context);
+	md5_starts(context);
+}
+
+void MD5Update(LT_MD5_CTX_T *context, const unsigned char *buf, unsigned len) {
+	md5_update(context, buf, len);
+}
+
+void MD5Final(unsigned char digest[16], LT_MD5_CTX_T *context) {
+	md5_finish(context, digest);
+}
+
+} // extern "C"
+
+#endif
diff --git a/arduino/libretuya/libraries/MD5/MD5PolarSSLImpl.h b/arduino/libretuya/libraries/MD5/MD5PolarSSLImpl.h
new file mode 100644
index 0000000..7cad1fc
--- /dev/null
+++ b/arduino/libretuya/libraries/MD5/MD5PolarSSLImpl.h
@@ -0,0 +1,16 @@
+/* Copyright (c) Kuba Szczodrzyński 2022-06-03. */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <polarssl/md5.h>
+#define LT_MD5_CTX_T md5_context
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#include "MD5.h"
diff --git a/arduino/realtek-ambz/libraries/MD5/MD5Impl.h b/arduino/realtek-ambz/libraries/MD5/MD5Impl.h
new file mode 100644
index 0000000..ba7753f
--- /dev/null
+++ b/arduino/realtek-ambz/libraries/MD5/MD5Impl.h
@@ -0,0 +1,7 @@
+/* Copyright (c) Kuba Szczodrzyński 2022-06-03. */
+
+#pragma once
+
+#include <sdk_extern.h>
+
+#define LT_MD5_USE_POLARSSL 1
diff --git a/builder/frameworks/realtek-ambz-sdk.py b/builder/frameworks/realtek-ambz-sdk.py
index 6847192..7de8817 100644
--- a/builder/frameworks/realtek-ambz-sdk.py
+++ b/builder/frameworks/realtek-ambz-sdk.py
@@ -180,6 +180,8 @@ env.AddLibrary(
         "+<component/common/mbed/hal_ext>",
         "+<component/common/mbed/targets/cmsis>",
         "+<component/common/mbed/targets/hal/rtl8711b>",
+        # keep PolarSSL for headers for ROM crypto functions
+        "+<component/common/network/ssl/polarssl-1.3.8/include>",
     ],
 )