samples: crypto: Add PBKDF2 sample

Add sample to demonstrate PBKDF2 use-case.

Signed-off-by: Joakim Andersson <[email protected]>

samples/crypto/pbkdf2/CMakeLists.txt

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+#
+# Copyright (c) 2023 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(pbkdf2)
+
+target_sources(app PRIVATE
+        src/main.c)

samples/crypto/pbkdf2/README.rst

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+.. _crypto_pbkdf2:
+
+Crypto: PBKDF2
+##############
+
+.. contents::
+   :local:
+   :depth: 2
+
+The Password Based Key Derivation Function (PBKDF2) sample shows how to derive keys with the PBKDF2 algorithm, using a sample password salt, and iteration count.
+The underlying pseudorandom function (PRF) used in this sample is HMAC with SHA-256.
+
+Requirements
+************
+
+The sample supports the following development kits:
+
+.. table-from-sample-yaml::
+
+.. include:: /includes/tfm.txt
+
+Overview
+********
+
+The sample performs the following operations:
+
+1. Initialization of the Platform Security Architecture (PSA) API.
+
+#. Key derivation:
+
+   a. Imports the input password into the PSA crypto keystore.
+   #. Derives the output key.
+
+#. Cleanup:
+
+   a. The input password is removed from the PSA crypto keystore.
+
+Building and running
+********************
+
+.. |sample path| replace:: :file:`samples/crypto/pbkdf2`
+
+.. include:: /includes/build_and_run_ns.txt
+
+Testing
+=======
+
+After programming the sample to your development kit, complete the following steps to test it:
+
+1. |connect_terminal|
+#. Compile and program the application.
+#. Observe the logs from the application using a terminal emulator.

samples/crypto/pbkdf2/boards/nrf52840dk_nrf52840.conf

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+# Enable both oberon driver and hardware crypto accelerator
+# Key derivation is only supported in software driver but is using chained
+# driver to accelerate sub-operations.
+CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y
+CONFIG_PSA_CRYPTO_DRIVER_OBERON=y

samples/crypto/pbkdf2/boards/nrf5340dk_nrf5340_cpuapp.conf

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+# Enable both oberon driver and hardware crypto accelerator
+# Key derivation is only supported in software driver but is using chained
+# driver to accelerate sub-operations.
+CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y
+CONFIG_PSA_CRYPTO_DRIVER_OBERON=y

samples/crypto/pbkdf2/boards/nrf5340dk_nrf5340_cpuapp_ns.conf

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+CONFIG_TFM_PROFILE_TYPE_NOT_SET=y
+
+# Using hardware crypto accelerator
+CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y

samples/crypto/pbkdf2/boards/nrf9160dk_nrf9160.conf

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+# Enable both oberon driver and hardware crypto accelerator
+# Key derivation is only supported in software driver but is using chained
+# driver to accelerate sub-operations.
+CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y
+CONFIG_PSA_CRYPTO_DRIVER_OBERON=y

samples/crypto/pbkdf2/boards/nrf9160dk_nrf9160_ns.conf

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+CONFIG_TFM_PROFILE_TYPE_NOT_SET=y
+
+# Using hardware crypto accelerator
+CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y

samples/crypto/pbkdf2/boards/nrf9160dk_nrf9160_ns.overlay

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+/*
+ * Copyright (c) 2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/* Disable uart1 in nonsecure since it is used by the TFM secure app. */
+&uart1 {
+	status = "disabled";
+};

samples/crypto/pbkdf2/prj.conf

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+# The Zephyr CMSIS emulation assumes that ticks are ms, currently
+CONFIG_SYS_CLOCK_TICKS_PER_SEC=1000
+
+CONFIG_MAIN_STACK_SIZE=4096
+CONFIG_HEAP_MEM_POOL_SIZE=4096
+
+# Enable logging
+CONFIG_CONSOLE=y
+CONFIG_LOG=y
+
+# Enable nordic security backend and PSA APIs
+CONFIG_NRF_SECURITY=y
+CONFIG_MBEDTLS_PSA_CRYPTO_C=y
+
+CONFIG_MBEDTLS_ENABLE_HEAP=y
+CONFIG_MBEDTLS_HEAP_SIZE=8192
+
+CONFIG_PSA_WANT_ALG_SHA_256=y
+CONFIG_PSA_WANT_ALG_HMAC=y
+CONFIG_PSA_WANT_ALG_PBKDF2_HMAC=y

samples/crypto/pbkdf2/sample.yaml

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+sample:
+  description: HMAC key derivation function example
+  name: PBKDF2 example
+tests:
+  sample.pbkdf2:
+    tags: introduction psa cc3xx
+    platform_allow: >
+      nrf5340dk_nrf5340_cpuapp
+      nrf9160dk_nrf9160 nrf52840dk_nrf52840
+    harness: console
+    harness_config:
+      type: multi_line
+      regex:
+        - ".*Example finished successfully!.*"
+    integration_platforms:
+      - nrf5340dk_nrf5340_cpuapp
+      - nrf9160dk_nrf9160
+      - nrf52840dk_nrf52840

samples/crypto/pbkdf2/src/main.c

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+/*
+ * Copyright (c) 2023 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/logging/log.h>
+#include <stdint.h>
+#include <psa/crypto.h>
+
+#ifdef CONFIG_BUILD_WITH_TFM
+#include <tfm_ns_interface.h>
+#endif
+
+#define APP_SUCCESS		(0)
+#define APP_ERROR		(-1)
+#define APP_SUCCESS_MESSAGE "Example finished successfully!"
+#define APP_ERROR_MESSAGE "Example exited with error!"
+
+#define PRINT_HEX(p_label, p_text, len)\
+	({\
+		LOG_INF("---- %s (len: %u): ----", p_label, len);\
+		LOG_HEXDUMP_INF(p_text, len, "Content:");\
+		LOG_INF("---- %s end  ----", p_label);\
+	})
+
+LOG_MODULE_REGISTER(pkbdf2, LOG_LEVEL_DBG);
+
+/* ====================================================================== */
+/*        Global variables/defines for the PBKDF2 example                 */
+
+#define PBKDF2_SAMPLE_INPUT_KEY_SIZE (6)
+#define PBKDF2_SAMPLE_SALT_SIZE (4)
+#define PBKDF2_SAMPLE_OUTPUT_KEY_SIZE (64)
+
+/* Test data from RFC 5869 Test Case 2
+ * https://datatracker.ietf.org/doc/html/rfc7914.html#section-11
+ */
+static const uint8_t m_input_password[PBKDF2_SAMPLE_INPUT_KEY_SIZE] = {
+	'p', 'a', 's', 's', 'w', 'd',
+};
+
+static const uint8_t m_salt[PBKDF2_SAMPLE_SALT_SIZE] = {
+	's', 'a', 'l', 't'
+};
+
+/* (NIST) "Recommendation for Password-Based Key Derivation:
+ * The iteration count shall be  selected as large as possible, as
+ * long as the time required to generate the key using the entered
+ * password is acceptable for the users. [...] A minimum iteration
+ * count of 1,000 is recommended.
+ */
+static uint32_t m_iteration_count = 1;
+
+/* Buffer to hold the output generated from PKBD2S */
+static uint8_t m_output_key[PBKDF2_SAMPLE_OUTPUT_KEY_SIZE];
+
+static const uint8_t m_expected_output_key[PBKDF2_SAMPLE_OUTPUT_KEY_SIZE] = {
+	0x55, 0xac, 0x04, 0x6e, 0x56, 0xe3, 0x08, 0x9f,
+	0xec, 0x16, 0x91, 0xc2, 0x25, 0x44, 0xb6, 0x05,
+	0xf9, 0x41, 0x85, 0x21, 0x6d, 0xde, 0x04, 0x65,
+	0xe6, 0x8b, 0x9d, 0x57, 0xc2, 0x0d, 0xac, 0xbc,
+	0x49, 0xca, 0x9c, 0xcc, 0xf1, 0x79, 0xb6, 0x45,
+	0x99, 0x16, 0x64, 0xb3, 0x9d, 0x77, 0xef, 0x31,
+	0x7c, 0x71, 0xb8, 0x45, 0xb1, 0xe3, 0x0b, 0xd5,
+	0x09, 0x11, 0x20, 0x41, 0xd3, 0xa1, 0x97, 0x83,
+};
+
+static psa_key_id_t m_input_key_id;
+static psa_key_id_t m_output_key_id;
+/* ====================================================================== */
+
+int crypto_init(void)
+{
+	psa_status_t status;
+
+	/* Initialize PSA Crypto */
+	status = psa_crypto_init();
+	if (status != PSA_SUCCESS)
+		return APP_ERROR;
+
+	return APP_SUCCESS;
+}
+
+int crypto_finish(void)
+{
+	psa_status_t status;
+
+	/* Destroy the key handle */
+	status = psa_destroy_key(m_input_key_id);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_destroy_key failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	status = psa_destroy_key(m_output_key_id);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_destroy_key failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	return APP_SUCCESS;
+}
+
+int import_input_password(void)
+{
+	psa_status_t status;
+	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+
+	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_DERIVE);
+	psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_VOLATILE);
+	psa_set_key_algorithm(&attributes, PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256));
+	psa_set_key_type(&attributes, PSA_KEY_TYPE_PASSWORD);
+	psa_set_key_bits(&attributes, PSA_BYTES_TO_BITS(PBKDF2_SAMPLE_INPUT_KEY_SIZE));
+
+	status = psa_import_key(&attributes, m_input_password, PBKDF2_SAMPLE_INPUT_KEY_SIZE,
+				&m_input_key_id);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_import_key failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	return APP_SUCCESS;
+}
+
+int derive_output_key(void)
+{
+	psa_status_t status;
+	int cmp_status;
+	psa_key_derivation_operation_t operation = PSA_KEY_DERIVATION_OPERATION_INIT;
+
+	status = psa_key_derivation_setup(&operation, PSA_ALG_PBKDF2_HMAC(PSA_ALG_SHA_256));
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_key_derivation_setup failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	status = psa_key_derivation_input_integer(&operation, PSA_KEY_DERIVATION_INPUT_COST,
+						  m_iteration_count);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_key_derivation_input_integer failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	status = psa_key_derivation_input_bytes(&operation, PSA_KEY_DERIVATION_INPUT_SALT, m_salt,
+						PBKDF2_SAMPLE_SALT_SIZE);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_key_derivation_input_bytes failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	status = psa_key_derivation_input_key(&operation, PSA_KEY_DERIVATION_INPUT_PASSWORD,
+					      m_input_key_id);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_key_derivation_input_key failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	/* This outputs the derived key as bytes to the application.
+	 * If the derived key is to be used for in cryptographic operations use
+	 * psa_key_derivation_output_key instead.
+	 */
+	status = psa_key_derivation_output_bytes(&operation, m_output_key,
+						 PBKDF2_SAMPLE_OUTPUT_KEY_SIZE);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_key_derivation_output_bytes failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	status = psa_key_derivation_abort(&operation);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_key_derivation_abort failed! (Error: %d)", status);
+		return APP_ERROR;
+	}
+
+	LOG_INF("Compare derived key with expected value...");
+	cmp_status = memcmp(m_expected_output_key, m_output_key, sizeof(m_output_key));
+	if (cmp_status != 0) {
+		LOG_INF("Error, the derived key doesn't match the expected value!");
+		return APP_ERROR;
+	}
+
+	LOG_INF("Key derivation successful!");
+	PRINT_HEX("Password", m_input_password, sizeof(m_input_password));
+	PRINT_HEX("Salt", m_salt, sizeof(m_salt));
+	LOG_INF("Iteration count: %d", m_iteration_count);
+	PRINT_HEX("Derived Key:", m_output_key, sizeof(m_output_key));
+
+	return APP_SUCCESS;
+}
+
+
+int main(void)
+{
+	int status;
+
+	LOG_INF("Starting PBKDF2 example...");
+
+	status = crypto_init();
+	if (status != APP_SUCCESS) {
+		LOG_INF(APP_ERROR_MESSAGE);
+		return APP_ERROR;
+	}
+
+	status = import_input_password();
+	if (status != APP_SUCCESS) {
+		LOG_INF(APP_ERROR_MESSAGE);
+		return APP_ERROR;
+	}
+
+	status = derive_output_key();
+	if (status != APP_SUCCESS) {
+		LOG_INF(APP_ERROR_MESSAGE);
+		return APP_ERROR;
+	}
+
+	status = crypto_finish();
+	if (status != APP_SUCCESS) {
+		LOG_INF(APP_ERROR_MESSAGE);
+		return APP_ERROR;
+	}
+
+	LOG_INF(APP_SUCCESS_MESSAGE);
+
+	return APP_SUCCESS;
+}