samples: crypto: Add Spake2+

Adds sample demonstrating Spake2+ usage through PSA Crypto APIs. Signed-off-by: Vidar Lillebø <vidar.lillebo@nordicsemi.no>
memfault · Mar 21, 2024 · 88523f2 · 88523f2
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diff --git a/doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst b/doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst
@@ -203,7 +203,7 @@ Cellular samples
 Cryptography samples
 --------------------
 
-|no_changes_yet_note|
+* Added :ref:`crypto_spake2p` sample.
 
 Debug samples
 -------------

diff --git a/samples/crypto/spake2p/CMakeLists.txt b/samples/crypto/spake2p/CMakeLists.txt
@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(spake2p)
+
+target_sources(app PRIVATE src/main.c)
diff --git a/samples/crypto/spake2p/README.rst b/samples/crypto/spake2p/README.rst
@@ -0,0 +1,41 @@
+.. _crypto_spake2p:
+
+Crypto: Spake2+
+###############
+
+.. contents::
+   :local:
+   :depth: 2
+
+The Spake2+ sample demonstrates how to do a password-authenticated key exchange using the Spake2+ protocol.
+
+Requirements
+************
+
+The sample supports the following development kits:
+
+.. table-from-sample-yaml::
+
+Overview
+********
+
+The sample performs the following operations:
+
+1. Initializes the Platform Security Architecture (PSA) API.
+#. Goes through the steps for Spake2+ on server and client sides.
+#. Verifies that the derived keys are the same.
+
+Building and running
+********************
+
+.. |sample path| replace:: :file:`samples/crypto/spake2p`
+
+
+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.
diff --git a/samples/crypto/spake2p/prj.conf b/samples/crypto/spake2p/prj.conf
@@ -0,0 +1,17 @@
+# Enable logging
+CONFIG_LOG=y
+CONFIG_CONSOLE=y
+
+CONFIG_MAIN_STACK_SIZE=16000
+
+# Enable nordic security backend and PSA APIs
+CONFIG_PSA_WANT_GENERATE_RANDOM=y
+CONFIG_NRF_SECURITY=y
+CONFIG_MBEDTLS_ENABLE_HEAP=y
+CONFIG_MBEDTLS_HEAP_SIZE=8192
+CONFIG_PSA_WANT_ALG_SPAKE2P_HMAC=y
+CONFIG_PSA_WANT_ALG_HKDF=y
+CONFIG_PSA_WANT_ALG_HMAC=y
+CONFIG_PSA_WANT_ALG_SHA_256=y
+CONFIG_PSA_WANT_ECC_SECP_R1_256=y
+CONFIG_PSA_WANT_KEY_TYPE_ECC_KEY_PAIR_IMPORT=y
diff --git a/samples/crypto/spake2p/sample.yaml b/samples/crypto/spake2p/sample.yaml
@@ -0,0 +1,24 @@
+sample:
+  description: This app provides an example of Spake2+
+  name: Spake2+ example
+tests:
+  sample.spake2p:
+    tags: introduction psa oberon
+    platform_allow: >
+      nrf5340dk_nrf5340_cpuapp
+      nrf9160dk_nrf9160 nrf52840dk_nrf52840
+      nrf9161dk_nrf9161
+      nrf54l15pdk_nrf54l15_cpuapp
+      nrf54h20pdk_nrf54h20_cpuapp
+    harness: console
+    harness_config:
+      type: multi_line
+      regex:
+        - ".*Example finished successfully!.*"
+    integration_platforms:
+      - nrf5340dk_nrf5340_cpuapp
+      - nrf9160dk_nrf9160
+      - nrf9161dk_nrf9161
+      - nrf52840dk_nrf52840
+      - nrf54l15pdk_nrf54l15_cpuapp
+      - nrf54h20pdk_nrf54h20_cpuapp
diff --git a/samples/crypto/spake2p/src/main.c b/samples/crypto/spake2p/src/main.c
@@ -0,0 +1,287 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#include <psa/crypto.h>
+#include <stdint.h>
+#include <zephyr/kernel.h>
+#include <zephyr/sys/printk.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/sys/util.h>
+
+LOG_MODULE_REGISTER(spake2p, LOG_LEVEL_DBG);
+
+#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);                                             \
+	})
+
+#define APP_SUCCESS	    (0)
+#define APP_ERROR	    (-1)
+#define APP_SUCCESS_MESSAGE "Example finished successfully!"
+#define APP_ERROR_MESSAGE   "Example exited with error!"
+
+/* w0 || w1 */
+static const uint8_t key_pair[] = {0x54, 0x8E, 0xC1, 0x42, 0xE2, 0x27, 0x90, 0x23, 0x7C, 0x67, 0xA8,
+				   0x88, 0x49, 0xE8, 0x61, 0xD3, 0x77, 0x00, 0x5F, 0x0A, 0x5C, 0x33,
+				   0x88, 0xF9, 0xAF, 0xA1, 0xC2, 0xFA, 0x58, 0xC7, 0xDA, 0x51, 0x35,
+				   0x99, 0xF8, 0x67, 0x1D, 0xBB, 0x67, 0x04, 0xA2, 0xC6, 0x3A, 0x78,
+				   0x4F, 0xC9, 0x5C, 0xD2, 0x8E, 0xBC, 0x55, 0x2E, 0xA4, 0x79, 0x98,
+				   0xB9, 0x18, 0x69, 0x9A, 0xB9, 0x3F, 0x4F, 0x7A, 0xD7};
+
+/* w0 || L */
+static const uint8_t public_key[] = {
+	0x54, 0x8E, 0xC1, 0x42, 0xE2, 0x27, 0x90, 0x23, 0x7C, 0x67, 0xA8, 0x88, 0x49, 0xE8,
+	0x61, 0xD3, 0x77, 0x00, 0x5F, 0x0A, 0x5C, 0x33, 0x88, 0xF9, 0xAF, 0xA1, 0xC2, 0xFA,
+	0x58, 0xC7, 0xDA, 0x51, 0x04, 0x81, 0x43, 0x3D, 0xC5, 0x93, 0xC9, 0x46, 0xC9, 0x37,
+	0xD9, 0x90, 0x26, 0xDD, 0x42, 0x14, 0x40, 0xE1, 0xC8, 0x7D, 0x0E, 0xC4, 0x94, 0x8B,
+	0xFF, 0x59, 0xEA, 0xF4, 0x77, 0xE3, 0x35, 0xE5, 0x52, 0x49, 0x66, 0xB2, 0x03, 0x31,
+	0x37, 0xD8, 0x4C, 0x65, 0x56, 0xDE, 0x07, 0x31, 0x57, 0x5C, 0xD2, 0x95, 0xC9, 0x75,
+	0x12, 0x4F, 0x52, 0x13, 0x25, 0xF7, 0x80, 0x01, 0xEC, 0xBE, 0x67, 0xE8, 0xB7};
+
+static psa_status_t send_message(psa_pake_operation_t *from, psa_pake_operation_t *to,
+				 psa_pake_step_t step)
+{
+	uint8_t data[1024];
+	size_t length;
+
+	psa_status_t status = psa_pake_output(from, step, data, sizeof(data), &length);
+
+	if (status) {
+		return status;
+	}
+	PRINT_HEX("send_message", data, length);
+	status = psa_pake_input(to, step, data, length);
+	return status;
+}
+
+static psa_status_t pake_setup(psa_pake_operation_t *op, psa_pake_role_t role, psa_key_id_t key,
+			       psa_pake_cipher_suite_t *cipher_suite)
+{
+	psa_status_t status;
+
+	status = psa_pake_setup(op, key, cipher_suite);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_pake_setup failed. (Error: %d)", status);
+		return status;
+	}
+
+	status = psa_pake_set_role(op, role);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_pake_set_role failed. (Error: %d)", status);
+		return status;
+	}
+
+	if (role == PSA_PAKE_ROLE_SERVER) {
+		status = psa_pake_set_user(op, "client", strlen("client"));
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_pake_set_user failed. (Error: %d)", status);
+			return status;
+		}
+
+		status = psa_pake_set_peer(op, "server", strlen("server"));
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_pake_set_peer failed. (Error: %d)", status);
+			return status;
+		}
+	} else {
+		status = psa_pake_set_user(op, "server", strlen("server"));
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_pake_set_user failed. (Error: %d)", status);
+			return status;
+		}
+
+		status = psa_pake_set_peer(op, "client", strlen("client"));
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_pake_set_peer failed. (Error: %d)", status);
+			return status;
+		}
+	}
+
+	return status;
+}
+
+int main(void)
+{
+	/* For Matter-compatible Spake2+, this will be PSA_ALG_SPAKE2P_MATTER */
+	psa_algorithm_t psa_spake_alg = PSA_ALG_SPAKE2P_HMAC(PSA_ALG_SHA_256);
+	psa_status_t status = psa_crypto_init();
+
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_crypto_init failed. (Error: %d)", status);
+	}
+
+	psa_pake_cipher_suite_t cipher_suite = PSA_PAKE_CIPHER_SUITE_INIT;
+
+	psa_pake_cs_set_algorithm(&cipher_suite, psa_spake_alg);
+	psa_pake_cs_set_primitive(&cipher_suite, PSA_PAKE_PRIMITIVE(PSA_PAKE_PRIMITIVE_TYPE_ECC,
+								    PSA_ECC_FAMILY_SECP_R1, 256));
+	psa_pake_cs_set_key_confirmation(&cipher_suite, PSA_PAKE_CONFIRMED_KEY);
+
+	psa_key_attributes_t key_attributes = PSA_KEY_ATTRIBUTES_INIT;
+
+	psa_set_key_usage_flags(&key_attributes, PSA_KEY_USAGE_DERIVE);
+	psa_set_key_algorithm(&key_attributes, psa_spake_alg);
+	psa_set_key_type(&key_attributes, PSA_KEY_TYPE_SPAKE2P_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
+	psa_set_key_bits(&key_attributes, 256);
+
+	psa_key_id_t key;
+
+	status = psa_import_key(&key_attributes, key_pair, sizeof(key_pair), &key);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_import_key failed. (Error: %d)", status);
+		goto error;
+	}
+
+	psa_set_key_usage_flags(&key_attributes, PSA_KEY_USAGE_DERIVE);
+	psa_set_key_algorithm(&key_attributes, psa_spake_alg);
+	psa_set_key_type(&key_attributes, PSA_KEY_TYPE_SPAKE2P_PUBLIC_KEY(PSA_ECC_FAMILY_SECP_R1));
+	psa_set_key_bits(&key_attributes, 256);
+
+	psa_key_id_t key_server;
+
+	status = psa_import_key(&key_attributes, public_key, sizeof(public_key), &key_server);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("psa_import_key failed. (Error: %d)", status);
+		goto error;
+	}
+
+	psa_reset_key_attributes(&key_attributes);
+
+	psa_pake_operation_t client_op = PSA_PAKE_OPERATION_INIT;
+
+	status = pake_setup(&client_op, PSA_PAKE_ROLE_CLIENT, key, &cipher_suite);
+	if (status != PSA_SUCCESS) {
+		goto error;
+	}
+
+	psa_pake_operation_t server_op = PSA_PAKE_OPERATION_INIT;
+
+	status = pake_setup(&server_op, PSA_PAKE_ROLE_SERVER, key, &cipher_suite);
+	if (status != PSA_SUCCESS) {
+		goto error;
+	}
+
+	/* Share P */
+	status = send_message(&client_op, &server_op, PSA_PAKE_STEP_KEY_SHARE);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("send_message failed. (Error: %d, step: %d)", status,
+			PSA_PAKE_STEP_KEY_SHARE);
+		goto error;
+	}
+
+	/* Share V */
+	status = send_message(&server_op, &client_op, PSA_PAKE_STEP_KEY_SHARE);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("send_message failed. (Error: %d, step: %d)", status,
+			PSA_PAKE_STEP_KEY_SHARE);
+		goto error;
+	}
+
+	/* Confirm P */
+	status = send_message(&server_op, &client_op, PSA_PAKE_STEP_CONFIRM);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("send_message failed. (Error: %d, step: %d)", status,
+			PSA_PAKE_STEP_CONFIRM);
+		goto error;
+	}
+
+	/* Confirm V */
+	status = send_message(&client_op, &server_op, PSA_PAKE_STEP_CONFIRM);
+	if (status != PSA_SUCCESS) {
+		LOG_INF("send_message failed. (Error: %d, step: %d)", status,
+			PSA_PAKE_STEP_CONFIRM);
+		goto error;
+	}
+
+	psa_key_derivation_operation_t kdf = PSA_KEY_DERIVATION_OPERATION_INIT;
+	uint8_t client_secret[32] = {0};
+	uint8_t server_secret[32] = {0};
+
+	psa_key_attributes_t shared_key_attributes = PSA_KEY_ATTRIBUTES_INIT;
+
+	psa_set_key_type(&shared_key_attributes, PSA_KEY_TYPE_DERIVE);
+	psa_set_key_usage_flags(&shared_key_attributes, PSA_KEY_USAGE_DERIVE);
+	psa_set_key_algorithm(&shared_key_attributes, PSA_ALG_HKDF(PSA_ALG_SHA_256));
+
+	struct {
+		psa_pake_operation_t *op;
+		uint8_t *secret;
+	} client_server[] = {{&client_op, client_secret}, {&server_op, server_secret}};
+
+	for (size_t i = 0; i < ARRAY_SIZE(client_server); i++) {
+		psa_key_id_t key;
+
+		status = psa_pake_get_shared_key(client_server[i].op, &shared_key_attributes, &key);
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_pake_get_shared_key failed. (Error: %d)", status);
+			goto error;
+		}
+
+		status = psa_key_derivation_setup(&kdf, PSA_ALG_HKDF(PSA_ALG_SHA_256));
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_key_derivation_setup failed. (Error: %d)", status);
+			goto error;
+		}
+
+		status = psa_key_derivation_input_key(&kdf, PSA_KEY_DERIVATION_INPUT_SECRET, key);
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_key_derivation_input_key failed. (Error: %d)", status);
+			goto error;
+		}
+
+		status = psa_key_derivation_input_bytes(&kdf, PSA_KEY_DERIVATION_INPUT_INFO, "Info",
+							4);
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_key_derivation_input_bytes failed. (Error: %d)", status);
+			goto error;
+		}
+
+		status = psa_key_derivation_output_bytes(&kdf, client_server[i].secret,
+							 sizeof(client_secret));
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_key_derivation_output_bytes failed. (Error: %d)", status);
+			goto error;
+		}
+
+		status = psa_key_derivation_abort(&kdf);
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_key_derivation_abort failed. (Error: %d)", status);
+			goto error;
+		}
+
+		status = psa_destroy_key(key);
+		if (status != PSA_SUCCESS) {
+			LOG_INF("psa_destroy_key failed. (Error: %d)", status);
+			goto error;
+		}
+	}
+
+	psa_reset_key_attributes(&shared_key_attributes);
+	PRINT_HEX("server_secret", client_secret, sizeof(client_secret));
+	PRINT_HEX("client_secret", server_secret, sizeof(server_secret));
+
+	bool compare_eq = true;
+
+	for (size_t i = 0; i < sizeof(server_secret); i++) {
+		if (server_secret[i] != client_secret[i]) {
+			compare_eq = false;
+		}
+	}
+
+	if (!compare_eq) {
+		LOG_ERR("Derived keys for server and client are not equal.");
+		goto error;
+	}
+
+	LOG_INF(APP_SUCCESS_MESSAGE);
+	return APP_SUCCESS;
+
+error:
+	LOG_INF(APP_ERROR_MESSAGE);
+	return APP_ERROR;
+}