pal: add crypto keys module

[KRKNWK-19108]
Add sidewalk pal module to store persistent keys.
It uses secure storage via psa api.

Signed-off-by: Krzysztof Taborowski <[email protected]>

Kconfig

@@ -211,6 +211,10 @@ config SIDEWALK_ON_DEV_CERT
 	bool "Enable Sidewalk on device certification"
 	depends on SHELL
 
+config SIDEWALK_CRYPTO_PSA_KEY_STORAGE
+	bool "Enable psa crypto storage for persistent Sidewalk keys [EXPERIMENTAL]"
+	select EXPERIMENTAL
+
 config SIDEWALK_PAL_RADIO_SOURCE
 	bool "Build sub-GHz radio driver from sources [EXPERIMENTAL]"
 	select EXPERIMENTAL

Kconfig.dependencies

@@ -76,6 +76,8 @@ config SIDEWALK_CRYPTO
 	imply PSA_WANT_KEY_TYPE_HMAC
 	imply PSA_WANT_GENERATE_RANDOM
 	imply MBEDTLS_ENABLE_HEAP
+	imply MBEDTLS_PSA_CRYPTO_STORAGE_C if SIDEWALK_CRYPTO_PSA_KEY_STORAGE
+	imply TRUSTED_STORAGE if SIDEWALK_CRYPTO_PSA_KEY_STORAGE
 	help
 	   Sidewalk security module
 

subsys/sal/sid_pal/include/sid_crypto_keys.h

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#ifndef SID_CRYPTO_KEYS_H
+#define SID_CRYPTO_KEYS_H
+
+#include <psa/crypto.h>
+
+/**
+ * @brief Persistent psa key ids used in Sidewalk.
+ */
+typedef enum {
+    SID_CRYPTO_MFG_ED25519_PRIV_KEY_ID = PSA_KEY_ID_USER_MIN,
+    SID_CRYPTO_MFG_SECP_256R1_PRIV_KEY_ID,
+    SID_CRYPTO_KV_WAN_MASTER_KEY_ID,
+    SID_CRYPTO_KV_APP_KEY_KEY_ID,
+    SID_CRYPTO_KV_PAN_KEY_ID,
+    SID_CRYPTO_KV_D2D_KEY_ID,
+    SID_CRYPTO_KEY_ID_LAST
+} sid_crypto_key_id_t;
+
+/**
+ * @brief Init secure key storage for Sidewalk keys.
+ * 
+ * @return 0 on success, or -errno on failure.
+ */
+int sid_crypto_keys_init(void);
+
+/**
+ * @brief Set key value.
+ * 
+ * @details On success:
+ * The raw key data buffer will be overwritten with key id and zeros.
+ * key value under given key id will be overwritten.
+ * 
+ * @param id [in] Key id to set with the new data.
+ * @param data [in/out] raw key data buffer on input.
+ *  overwrite with key id on output.
+ * @param size [in] size of raw key data buffer.
+ * @return 0 on success, or -errno on failure.
+ */
+int sid_crypto_keys_set(psa_key_id_t id, uint8_t *data, size_t size);
+
+/**
+ * @brief Get key id by data.
+ * 
+ * @param id [out] psa key id from key data buffer.
+ *  If key not found set to PSA_KEY_ID_NULL.
+ * @param data [in] key data buffer.
+ * @param size [in] size of key data buffer.
+ * @return 0 on success, or -errno on failure.
+ *  -ENOENT - if key not found.
+ */
+int sid_crypto_keys_get(psa_key_id_t *id, uint8_t *data, size_t size);
+
+
+/**
+ * @brief Deinit sidewalk key storage.
+ * 
+ * @return 0 on success, or -errno on failure. 
+ */
+int sid_crypto_keys_deinit(void);
+
+#endif /* SID_CRYPTO_KEYS_H */

subsys/sal/sid_pal/src/CMakeLists.txt

@@ -33,6 +33,7 @@ zephyr_library_sources_ifdef(CONFIG_SIDEWALK_VENDOR_SERVICE sid_ble_vnd_service.
 zephyr_library_sources_ifdef(CONFIG_SIDEWALK_LOGGING_SERVICE sid_ble_log_service.c)
 
 zephyr_library_sources_ifdef(CONFIG_SIDEWALK_CRYPTO sid_crypto.c)
+zephyr_library_sources_ifdef(CONFIG_SIDEWALK_CRYPTO_PSA_KEY_STORAGE sid_crypto_keys.c)
 
 zephyr_library_sources_ifdef(CONFIG_SIDEWALK_MFG_STORAGE sid_mfg_storage.c)
 

subsys/sal/sid_pal/src/sid_crypto_keys.c

@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#include <sid_crypto_keys.h>
+#include <errno.h>
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_REGISTER(sid_crypto_key, CONFIG_SIDEWALK_CRYPTO_LOG_LEVEL);
+#define ESUCCESS (0)
+
+#ifdef CONFIG_TRUSTED_STORAGE_BACKEND_AEAD_KEY_DERIVE_FROM_HUK
+#include <hw_unique_key.h>
+#ifndef HUK_HAS_KMU
+#include <zephyr/sys/reboot.h>
+#endif /* HUK_HAS_KMU */
+
+static int write_huk(void)
+{
+	if (!hw_unique_key_are_any_written()) {
+		int result = hw_unique_key_write_random();
+		if (result != HW_UNIQUE_KEY_SUCCESS) {
+			LOG_ERR("hw_unique_key_write_random error: %d", result);
+			return 0;
+		}
+		LOG_INF("Writing random keys to KMU Success!");
+#if !defined(HUK_HAS_KMU)
+		/* Reboot to allow the bootloader to load the key into CryptoCell. */
+		sys_reboot(0);
+#endif /* !defined(HUK_HAS_KMU) */
+	}
+
+	return 0;
+}
+#endif /* CONFIG_TRUSTED_STORAGE_BACKEND_AEAD_KEY_DERIVE_FROM_HUK */
+
+int sid_crypto_keys_init(void)
+{
+	int err = ESUCCESS;
+#ifdef CONFIG_TRUSTED_STORAGE_BACKEND_AEAD_KEY_DERIVE_FROM_HUK
+	err = write_huk();
+#endif /* CONFIG_TRUSTED_STORAGE_BACKEND_AEAD_KEY_DERIVE_FROM_HUK */
+
+	return err;
+}
+
+int sid_crypto_keys_set(psa_key_id_t id, uint8_t *data, size_t size)
+{
+	/* Check arguments */
+	if (PSA_KEY_ID_NULL == id || !data || !size) {
+		return -EINVAL;
+	}
+
+	/* Remove the key if any exists */
+	psa_status_t status = PSA_ERROR_GENERIC_ERROR;
+	status = psa_destroy_key(id);
+	if (PSA_SUCCESS != status && PSA_ERROR_INVALID_HANDLE != status) {
+		LOG_ERR("psa_destroy_key failed! (err %d id %d)", status, id);
+	}
+
+	/* Configure the key attributes */
+	psa_key_id_t out_id = PSA_KEY_ID_NULL;
+	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+	size_t key_bits = 0;
+	psa_key_usage_t usage_flags = 0;
+	psa_algorithm_t alg = PSA_ALG_NONE;
+	psa_key_type_t type = PSA_KEY_TYPE_NONE;
+
+	switch (id) {
+	case SID_CRYPTO_MFG_ED25519_PRIV_KEY_ID:
+		usage_flags = PSA_KEY_USAGE_SIGN_HASH;
+		alg = PSA_ALG_PURE_EDDSA;
+		type = PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_TWISTED_EDWARDS);
+		key_bits = 255;
+		break;
+	case SID_CRYPTO_MFG_SECP_256R1_PRIV_KEY_ID:
+		usage_flags = PSA_KEY_USAGE_SIGN_HASH;
+		alg = PSA_ALG_ECDSA(PSA_ALG_SHA_256);
+		type = PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1);
+		key_bits = 256;
+		break;
+	case SID_CRYPTO_KV_WAN_MASTER_KEY_ID:
+	case SID_CRYPTO_KV_APP_KEY_KEY_ID:
+	case SID_CRYPTO_KV_PAN_KEY_ID:
+	case SID_CRYPTO_KV_D2D_KEY_ID:
+		usage_flags = PSA_KEY_USAGE_SIGN_MESSAGE;
+		alg = PSA_ALG_CMAC;
+		type = PSA_KEY_TYPE_AES;
+		key_bits = 128;
+		/* TODO: What if one key can be used with two algs, eg PSA_ALG_CMAC and PSA_ALG_CTR? Should it be saved twice? */
+		break;
+	default:
+		LOG_ERR("Unknow persistent key id %d", id);
+		return -ENOENT;
+	}
+
+	psa_reset_key_attributes(&attributes);
+	psa_set_key_usage_flags(&attributes, usage_flags);
+	psa_set_key_algorithm(&attributes, alg);
+	psa_set_key_type(&attributes, type);
+	psa_set_key_bits(&attributes, key_bits);
+
+	psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_PERSISTENT);
+	psa_set_key_id(&attributes, id);
+
+	/* Import key to secure storage */
+	status = psa_import_key(&attributes, data, size, &out_id);
+	if (PSA_SUCCESS == status && out_id == id) {
+		LOG_HEXDUMP_DBG(data, size, "found new key: ");
+	} else {
+		LOG_ERR("psa_import_key failed! (err %d id %d)", status, out_id);
+		return -EACCES;
+	}
+
+	/* Clear key data other then key id*/
+	memset(data, 0, size);
+	psa_key_id_t *data_id = (psa_key_id_t *)data;
+	*data_id = id;
+	LOG_HEXDUMP_DBG(data, size, "saved new key: ");
+
+	status = psa_purge_key(id);
+	if (status != PSA_SUCCESS) {
+		LOG_ERR("psa_purge_key failed! (err %d id %d)", status, id);
+		return -EFAULT;
+	}
+
+	psa_reset_key_attributes(&attributes);
+
+	return ESUCCESS;
+}
+
+int sid_crypto_keys_get(psa_key_id_t *id, uint8_t *data, size_t size)
+{
+	if (!id || !data || !size) {
+		return -EINVAL;
+	}
+
+	/* if key not found, assign null id */
+	*id = PSA_KEY_ID_NULL;
+
+	/* Check if a key data cosists only of key id and zeros */
+	psa_key_id_t *data_id = (psa_key_id_t *)data;
+	if (SID_CRYPTO_KEY_ID_LAST <= *data_id || PSA_KEY_ID_USER_MIN > *data_id) {
+		return -ENOENT;
+	}
+
+	for (size_t i = sizeof(psa_key_id_t); i < size; i++) {
+		if (0x00 != data[i]) {
+			return -ENOENT;
+		}
+	}
+
+	memcpy(id, data_id, sizeof(psa_key_id_t));
+	LOG_DBG("found persistent key: %d", *id);
+	return ESUCCESS;
+}
+
+int sid_crypto_keys_deinit(void)
+{
+	/* Nothing to do, left for stable api for future features */
+	return ESUCCESS;
+}

tests/functional/crypto_keys/CMakeLists.txt

@@ -0,0 +1,15 @@
+#
+# Copyright (c) 2022 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(sidewalk_functional_test)
+
+# add test file
+FILE(GLOB app_sources src/*.c)
+target_sources(app PRIVATE ${app_sources})
+target_include_directories(app PRIVATE . src)

tests/functional/crypto_keys/Kconfig

@@ -0,0 +1,38 @@
+#
+# Copyright (c) 2022 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+config SIDEWALK_BUILD
+	default y
+
+config SIDEWALK_CRYPTO
+	default y
+
+config SIDEWALK_STORAGE
+	default y
+
+config SIDEWALK_CRYPTO_PSA_KEY_STORAGE
+	default y
+
+config SIDEWALK_CRYPTO_LOG_LEVEL
+	default 0
+
+config SIDEWALK_LOG_LEVEL
+	default 0
+
+# Stacks
+config MAIN_STACK_SIZE
+	default 8192
+
+config ZTEST_STACK_SIZE
+	default 8192
+
+config HEAP_MEM_POOL_SIZE
+	default 4096
+
+config MBEDTLS_HEAP_SIZE
+	default 4096
+
+source "Kconfig.zephyr"
+source "${ZEPHYR_BASE}/../sidewalk/Kconfig.dependencies"

tests/functional/crypto_keys/boards/nrf52840dk_nrf52840.conf

@@ -0,0 +1,7 @@
+#
+# Copyright (c) 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_REBOOT=y

tests/functional/crypto_keys/boards/nrf5340dk_nrf5340_cpuapp_ns.conf

@@ -0,0 +1,11 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_TFM_PROFILE_TYPE_NOT_SET=y
+
+# Using hardware crypto accelerator
+CONFIG_PSA_CRYPTO_DRIVER_OBERON=n
+CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y

tests/functional/crypto_keys/prj.conf

@@ -0,0 +1,8 @@
+#
+# Copyright (c) 2022 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+CONFIG_ZTEST=y
+CONFIG_MAIN_THREAD_PRIORITY=14
+CONFIG_NVS_LOG_LEVEL_WRN=y