STM32: add otp_crypto with mbedTLS

.github/workflows/stm32-build.yaml

@@ -70,6 +70,9 @@ jobs:
             renode_platform: stm32f4.repl
             avm_address: "0x08060000"
             skip_i2c_test: true
+            # No RNG peripheral on F411, so the firmware has no crypto NIFs
+            # (mbedTLS is excluded by STM32_HAS_RNG in CMake).
+            skip_crypto_test: true
           - device: stm32f429zit6
             max_size: 524288
           - device: stm32h743vit6
@@ -100,6 +103,9 @@ jobs:
             # register layout) but the L5 HAL uses the newer I2C registers
             # (TIMINGR, ISR, etc.), causing a complete register mismatch.
             skip_i2c_test: true
+            # 512 KB flash with avm_address=0x08060000 leaves only 128 KB,
+            # but the crypto AVM is 207 KB and gets truncated.
+            skip_crypto_test: true
           - device: stm32f207zgt6
             max_size: 524288
           - device: stm32u375rgt6
@@ -108,6 +114,10 @@ jobs:
             max_size: 393216
             renode_platform: stm32g0b1.repl
             avm_address: "0x08060000"
+            # No RNG peripheral on G0B1 (only G041/G061/G081/G0C1 have one),
+            # so the firmware has no crypto NIFs (mbedTLS is excluded by
+            # STM32_HAS_RNG in CMake).
+            skip_crypto_test: true
 
     steps:
     - uses: erlef/setup-beam@v1
@@ -185,7 +195,7 @@ jobs:
         mkdir build-host
         cd build-host
         cmake .. -G Ninja
-        cmake --build . -t stm32_boot_test stm32_gpio_test stm32_i2c_test stm32_spi_test
+        cmake --build . -t stm32_boot_test stm32_gpio_test stm32_i2c_test stm32_spi_test stm32_crypto_test
 
     - name: Install Renode
       if: matrix.renode_platform
@@ -256,3 +266,21 @@ jobs:
           --variable AVM:@$PWD/build-host/src/platforms/stm32/tests/test_erl_sources/stm32_spi_test.avm \
           --variable AVM_ADDRESS:${{ matrix.avm_address }} \
           --variable PLATFORM:$PLATFORM
+
+    - name: Run Renode crypto test
+      # Devices without RNG hardware (F411 / G0) don't ship mbedTLS at all;
+      # L562 has only 512 KB of flash and the 207 KB crypto AVM is truncated
+      # at AVM_ADDRESS=0x08060000, which kills kernel boot.
+      if: matrix.renode_platform && !matrix.skip_crypto_test
+      run: |
+        LOCAL_REPL="src/platforms/stm32/tests/renode/${{ matrix.renode_platform }}"
+        if [ -f "$LOCAL_REPL" ]; then
+          PLATFORM="@$PWD/$LOCAL_REPL"
+        else
+          PLATFORM="@platforms/cpus/${{ matrix.renode_platform }}"
+        fi
+        renode-test src/platforms/stm32/tests/renode/stm32_crypto_test.robot \
+          --variable ELF:@$PWD/src/platforms/stm32/build/AtomVM-${{ matrix.device }}.elf \
+          --variable AVM:@$PWD/build-host/src/platforms/stm32/tests/test_erl_sources/stm32_crypto_test.avm \
+          --variable AVM_ADDRESS:${{ matrix.avm_address }} \
+          --variable PLATFORM:$PLATFORM

src/platforms/stm32/cmake/stm32_device.cmake

@@ -143,9 +143,22 @@ elseif (STM32_FAMILY_SHORT STREQUAL "wb")
     } >RAM_SHARED AT> FLASH]=])
 endif()
 
+# Per ST AN4230 Rev 13, Table 2:
+# https://www.st.com/resource/en/application_note/dm00073853-stm32-microcontroller-random-number-generation-validation-using-the-nist-statistical-test-suite-stmicroelectronics.pdf
+if (DEVICE_LOWER MATCHES "^stm32(f2|f7|g4|h5|h7|l4|u3|u5|wb)")
+    set(STM32_HAS_RNG TRUE)
+elseif (DEVICE_LOWER MATCHES "^stm32f4(05|15|07|17|10|12|13|23|27|37|29|39|69|79)")
+    set(STM32_HAS_RNG TRUE)
+elseif (DEVICE_LOWER MATCHES "^stm32g0(41|61|81|c1)")
+    set(STM32_HAS_RNG TRUE)
+else()
+    set(STM32_HAS_RNG FALSE)
+endif()
+
 message("-----------Device Info-----------")
 message(STATUS "Device      : ${DEVICE}")
 message(STATUS "Family      : ${STM32_FAMILY}")
 message(STATUS "CPU         : ${STM32_CPU}")
 message(STATUS "FPU         : ${STM32_FPU}")
 message(STATUS "Arch Flags  : ${_arch_flags_str}")
+message(STATUS "Has RNG     : ${STM32_HAS_RNG}")

src/platforms/stm32/cmake/stm32_hal_conf.h.in

@@ -41,6 +41,7 @@ extern "C" {
 #define HAL_DMA_MODULE_ENABLED
 #define HAL_I2C_MODULE_ENABLED
 #define HAL_SPI_MODULE_ENABLED
+#define HAL_RNG_MODULE_ENABLED
 #if defined(STM32H5XX) || defined(STM32L5XX) || defined(STM32U3XX) || defined(STM32U5XX)
 #define HAL_ICACHE_MODULE_ENABLED
 #endif
@@ -204,6 +205,10 @@ extern "C" {
 #include "@STM32_FAMILY@_hal_spi.h"
 #endif
 
+#ifdef HAL_RNG_MODULE_ENABLED
+#include "@STM32_FAMILY@_hal_rng.h"
+#endif
+
 #ifdef HAL_ICACHE_MODULE_ENABLED
 #include "@STM32_FAMILY@_hal_icache.h"
 #endif

src/platforms/stm32/src/CMakeLists.txt

@@ -60,6 +60,13 @@ if (EXISTS "${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_spi_ex.c")
     list(APPEND HAL_SOURCES ${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_spi_ex.c)
 endif()
 
+if (EXISTS "${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_rng.c")
+    list(APPEND HAL_SOURCES ${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_rng.c)
+endif()
+if (EXISTS "${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_rng_ex.c")
+    list(APPEND HAL_SOURCES ${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_rng_ex.c)
+endif()
+
 # ICACHE HAL for families that have it (U5, H5)
 if (EXISTS "${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_icache.c")
     list(APPEND HAL_SOURCES ${HAL_DRIVER_SRC_DIR}/${STM32_FAMILY}_hal_icache.c)

src/platforms/stm32/src/lib/CMakeLists.txt

@@ -21,6 +21,26 @@
 cmake_minimum_required (VERSION 3.13)
 project (libAtomVMPlatformSTM32)
 
+if (STM32_HAS_RNG)
+    # Skip mbedTLS programs/tests that pull in POSIX-only code (sockets,
+    # stdio, etc.) and won't link on bare metal anyway.
+    set(ENABLE_PROGRAMS OFF CACHE BOOL "" FORCE)
+    set(ENABLE_TESTING OFF CACHE BOOL "" FORCE)
+
+    include(FetchMbedTLS)
+
+    # Apply our user config only to the mbedtls targets, not to the rest
+    # of the firmware.
+    set(_mbedtls_stm32_cfg "MBEDTLS_USER_CONFIG_FILE=\"${CMAKE_CURRENT_SOURCE_DIR}/mbedtls_stm32_user_config.h\"")
+    foreach(_tgt mbedcrypto mbedtls mbedx509)
+        if(TARGET ${_tgt})
+            target_compile_definitions(${_tgt} PRIVATE "${_mbedtls_stm32_cfg}")
+        endif()
+    endforeach()
+    unset(_mbedtls_stm32_cfg)
+    unset(_tgt)
+endif()
+
 set(HEADER_FILES
     avm_devcfg.h
     avm_log.h
@@ -41,6 +61,14 @@ set(SOURCE_FILES
     ../../../../libAtomVM/portnifloader.c
 )
 
+if (STM32_HAS_RNG)
+    list(APPEND HEADER_FILES
+        ../../../../libAtomVM/otp_crypto.h)
+    list(APPEND SOURCE_FILES
+        ../../../../libAtomVM/otp_crypto.c
+        otp_crypto_platform.c)
+endif()
+
 set(
     PLATFORM_LIB_SUFFIX
     ${CMAKE_SYSTEM_NAME}-${CMAKE_SYSTEM_PROCESSOR}
@@ -53,6 +81,12 @@ if(CMAKE_COMPILER_IS_GNUCC)
 endif()
 
 target_link_libraries(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC libAtomVM)
+if (STM32_HAS_RNG)
+    target_compile_definitions(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC ATOMVM_HAS_MBEDTLS)
+    target_compile_definitions(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC
+        "MBEDTLS_USER_CONFIG_FILE=\"${CMAKE_CURRENT_SOURCE_DIR}/mbedtls_stm32_user_config.h\"")
+    target_link_libraries(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC MbedTLS::mbedcrypto)
+endif()
 target_link_options(libAtomVM${PLATFORM_LIB_SUFFIX} PUBLIC ${LINK_OPTIONS} -Wl,--whole-archive ${CMAKE_CURRENT_BINARY_DIR}/liblibAtomVMGeneric-arm.a -Wl,--no-whole-archive)
 
 # Include HAL/CMSIS headers

src/platforms/stm32/src/lib/mbedtls_stm32_user_config.h

@@ -0,0 +1,67 @@
+/*
+ * This file is part of AtomVM.
+ *
+ * Copyright 2026 Paul Guyot <pguyot@kallisys.net>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+ */
+
+#ifndef MBEDTLS_STM32_USER_CONFIG_H
+#define MBEDTLS_STM32_USER_CONFIG_H
+
+#define MBEDTLS_NO_PLATFORM_ENTROPY
+#define MBEDTLS_PLATFORM_MS_TIME_ALT
+
+#undef MBEDTLS_HAVE_TIME_DATE
+#undef MBEDTLS_TIMING_C
+
+#undef MBEDTLS_PSA_CRYPTO_C
+#undef MBEDTLS_PSA_CRYPTO_STORAGE_C
+#undef MBEDTLS_PSA_ITS_FILE_C
+#undef MBEDTLS_PSA_CRYPTO_CLIENT
+#undef MBEDTLS_PSA_INJECT_ENTROPY
+#undef MBEDTLS_LMS_C
+
+#undef MBEDTLS_FS_IO
+
+#undef MBEDTLS_NET_C
+#undef MBEDTLS_SSL_TLS_C
+#undef MBEDTLS_SSL_CLI_C
+#undef MBEDTLS_SSL_SRV_C
+#undef MBEDTLS_SSL_SERVER_NAME_INDICATION
+#undef MBEDTLS_SSL_DTLS_HELLO_VERIFY
+#undef MBEDTLS_SSL_DTLS_ANTI_REPLAY
+#undef MBEDTLS_SSL_DTLS_CONNECTION_ID
+#undef MBEDTLS_SSL_PROTO_DTLS
+#undef MBEDTLS_SSL_PROTO_TLS1_2
+#undef MBEDTLS_SSL_PROTO_TLS1_3
+#undef MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
+#undef MBEDTLS_SSL_KEEP_PEER_CERTIFICATE
+#undef MBEDTLS_SSL_RENEGOTIATION
+#undef MBEDTLS_SSL_TICKET_C
+#undef MBEDTLS_SSL_COOKIE_C
+#undef MBEDTLS_SSL_CACHE_C
+#undef MBEDTLS_X509_USE_C
+#undef MBEDTLS_X509_CREATE_C
+#undef MBEDTLS_X509_CRT_PARSE_C
+#undef MBEDTLS_X509_CRL_PARSE_C
+#undef MBEDTLS_X509_CSR_PARSE_C
+#undef MBEDTLS_X509_CRT_WRITE_C
+#undef MBEDTLS_X509_CSR_WRITE_C
+#undef MBEDTLS_PKCS7_C
+
+#undef MBEDTLS_SELF_TEST
+
+#endif /* MBEDTLS_STM32_USER_CONFIG_H */

src/platforms/stm32/src/lib/otp_crypto_platform.c

@@ -0,0 +1,26 @@
+/*
+ * This file is part of AtomVM.
+ *
+ * Copyright 2026 by Paul Guyot <pguyot@kallisys.net>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
+ */
+
+#include <nifs.h>
+#include <otp_crypto.h>
+
+#include "stm_sys.h"
+
+REGISTER_NIF_COLLECTION(otp_crypto, NULL, NULL, otp_crypto_nif_get_nif)

src/platforms/stm32/src/lib/platform_nifs.c

@@ -23,6 +23,10 @@
 #include <platform_nifs.h>
 #include <term.h>
 
+#ifdef ATOMVM_HAS_MBEDTLS
+#include <otp_crypto.h>
+#endif
+
 // #define ENABLE_TRACE
 #include <trace.h>
 
@@ -47,9 +51,5 @@ const struct Nif *platform_nifs_get_nif(const char *nifname)
         TRACE("Resolved platform nif %s ...\n", nifname);
         return &atomvm_platform_nif;
     }
-    const struct Nif *nif = nif_collection_resolve_nif(nifname);
-    if (nif) {
-        return nif;
-    }
-    return NULL;
+    return nif_collection_resolve_nif(nifname);
 }

src/platforms/stm32/src/lib/stm_sys.h

@@ -26,6 +26,11 @@
 
 #include "stm32_hal_platform.h"
 
+#ifdef ATOMVM_HAS_MBEDTLS
+#include <mbedtls/ctr_drbg.h>
+#include <mbedtls/entropy.h>
+#endif
+
 #define STM32_ATOM globalcontext_make_atom(ctx->global, ATOM_STR("\x5", "stm32"))
 
 /* Define macros for data and instruction barriers for sys_init_icache() */
@@ -46,6 +51,13 @@ struct LockedPin
 struct STM32PlatformData
 {
     struct ListHead locked_pins;
+#ifdef ATOMVM_HAS_MBEDTLS
+    RNG_HandleTypeDef rng;
+    mbedtls_entropy_context entropy_ctx;
+    mbedtls_ctr_drbg_context random_ctx;
+    bool entropy_is_initialized;
+    bool random_is_initialized;
+#endif
 };
 
 void sys_init_icache(void);