modules/openthread/platform/crypto_psa.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /*
  * Copyright (c) 2021 Nordic Semiconductor ASA
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #include <openthread/platform/crypto.h>

 #include <psa/crypto.h>

 #if defined(CONFIG_OPENTHREAD_ECDSA)
 #include <string.h>
 #include <zephyr/sys/__assert.h>
 #endif

 static otError psaToOtError(psa_status_t aStatus)
 {
 	switch (aStatus) {
 	case PSA_SUCCESS:
 		return OT_ERROR_NONE;
 	case PSA_ERROR_INVALID_ARGUMENT:
 		return OT_ERROR_INVALID_ARGS;
 	case PSA_ERROR_BUFFER_TOO_SMALL:
 		return OT_ERROR_NO_BUFS;
 	default:
 		return OT_ERROR_FAILED;
 	}
 }

 static psa_key_type_t toPsaKeyType(otCryptoKeyType aType)
 {
 	switch (aType) {
 	case OT_CRYPTO_KEY_TYPE_RAW:
 		return PSA_KEY_TYPE_RAW_DATA;
 	case OT_CRYPTO_KEY_TYPE_AES:
 		return PSA_KEY_TYPE_AES;
 	case OT_CRYPTO_KEY_TYPE_HMAC:
 		return PSA_KEY_TYPE_HMAC;
 	default:
 		return PSA_KEY_TYPE_NONE;
 	}
 }

 static psa_algorithm_t toPsaAlgorithm(otCryptoKeyAlgorithm aAlgorithm)
 {
 	switch (aAlgorithm) {
 	case OT_CRYPTO_KEY_ALG_AES_ECB:
 		return PSA_ALG_ECB_NO_PADDING;
 	case OT_CRYPTO_KEY_ALG_HMAC_SHA_256:
 		return PSA_ALG_HMAC(PSA_ALG_SHA_256);
 	default:
 		/*
 		 * There is currently no constant like PSA_ALG_NONE, but 0 is used
 		 * to indicate an unknown algorithm.
 		 */
 		return (psa_algorithm_t) 0;
 	}
 }

 static psa_key_usage_t toPsaKeyUsage(int aUsage)
 {
 	psa_key_usage_t usage = 0;

 	if (aUsage & OT_CRYPTO_KEY_USAGE_EXPORT) {
 		usage |= PSA_KEY_USAGE_EXPORT;
 	}

 	if (aUsage & OT_CRYPTO_KEY_USAGE_ENCRYPT) {
 		usage |= PSA_KEY_USAGE_ENCRYPT;
 	}

 	if (aUsage & OT_CRYPTO_KEY_USAGE_DECRYPT) {
 		usage |= PSA_KEY_USAGE_DECRYPT;
 	}

 	if (aUsage & OT_CRYPTO_KEY_USAGE_SIGN_HASH) {
 		usage |= PSA_KEY_USAGE_SIGN_HASH;
 	}

 	return usage;
 }

 static bool checkKeyUsage(int aUsage)
 {
 	/* Check if only supported flags have been passed */
 	int supported_flags = OT_CRYPTO_KEY_USAGE_EXPORT |
 			      OT_CRYPTO_KEY_USAGE_ENCRYPT |
 			      OT_CRYPTO_KEY_USAGE_DECRYPT |
 			      OT_CRYPTO_KEY_USAGE_SIGN_HASH;

 	return (aUsage & ~supported_flags) == 0;
 }

 static bool checkContext(otCryptoContext *aContext, size_t aMinSize)
 {
 	/* Verify that the passed context is initialized and points to a big enough buffer */
 	return aContext != NULL && aContext->mContext != NULL && aContext->mContextSize >= aMinSize;
 }

 static void ensureKeyIsLoaded(otCryptoKeyRef aKeyRef)
 {
 	/*
 	 * The workaround below will no longer be need after updating TF-M version used in Zephyr
 	 * to 1.5.0 (see upstream commit 42e77b561fcfe19819ff1e63cb7c0b672ee8ba41).
 	 * In the recent versions of TF-M the concept of key handles and psa_open_key()/
 	 * psa_close_key() APIs have been being deprecated, but the version currently used in Zephyr
 	 * is in the middle of that transition. Consequently, psa_destroy_key() and lots of other
 	 * functions will fail when a key ID that they take as a parameter is not loaded from the
 	 * persistent storage. That may occur when a given persistent key is created via
 	 * psa_generate_key() or psa_import_key(), and then the device reboots.
 	 *
 	 * Use psa_open_key() when the key has not been loaded yet to work around the issue.
 	 */
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_status_t status = psa_get_key_attributes(aKeyRef, &attributes);
 	psa_key_id_t key_handle;

 	if (status == PSA_ERROR_INVALID_HANDLE) {
 		psa_open_key(aKeyRef, &key_handle);
 	}

 	psa_reset_key_attributes(&attributes);
 }

 void otPlatCryptoInit(void)
 {
 	psa_crypto_init();
 }

 otError otPlatCryptoImportKey(otCryptoKeyRef *aKeyRef,
 			      otCryptoKeyType aKeyType,
 			      otCryptoKeyAlgorithm aKeyAlgorithm,
 			      int aKeyUsage,
 			      otCryptoKeyStorage aKeyPersistence,
 			      const uint8_t *aKey,
 			      size_t aKeyLen)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_status_t status;

 	if (aKeyRef == NULL || aKey == NULL || !checkKeyUsage(aKeyUsage)) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	psa_set_key_type(&attributes, toPsaKeyType(aKeyType));
 	psa_set_key_algorithm(&attributes, toPsaAlgorithm(aKeyAlgorithm));
 	psa_set_key_usage_flags(&attributes, toPsaKeyUsage(aKeyUsage));

 	switch (aKeyPersistence) {
 	case OT_CRYPTO_KEY_STORAGE_PERSISTENT:
 		psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_PERSISTENT);
 		psa_set_key_id(&attributes, *aKeyRef);
 		break;
 	case OT_CRYPTO_KEY_STORAGE_VOLATILE:
 		psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_VOLATILE);
 		break;
 	}

 	status = psa_import_key(&attributes, aKey, aKeyLen, aKeyRef);
 	psa_reset_key_attributes(&attributes);

 	return psaToOtError(status);
 }

 otError otPlatCryptoExportKey(otCryptoKeyRef aKeyRef,
 			      uint8_t *aBuffer,
 			      size_t aBufferLen,
 			      size_t *aKeyLen)
 {
 	if (aBuffer == NULL) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	ensureKeyIsLoaded(aKeyRef);

 	return psaToOtError(psa_export_key(aKeyRef, aBuffer, aBufferLen, aKeyLen));
 }

 otError otPlatCryptoDestroyKey(otCryptoKeyRef aKeyRef)
 {
 	ensureKeyIsLoaded(aKeyRef);

 	return psaToOtError(psa_destroy_key(aKeyRef));
 }

 bool otPlatCryptoHasKey(otCryptoKeyRef aKeyRef)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_status_t status;

 	ensureKeyIsLoaded(aKeyRef);
 	status = psa_get_key_attributes(aKeyRef, &attributes);
 	psa_reset_key_attributes(&attributes);

 	return status == PSA_SUCCESS;
 }

 otError otPlatCryptoHmacSha256Init(otCryptoContext *aContext)
 {
 	psa_mac_operation_t *operation;

 	if (!checkContext(aContext, sizeof(psa_mac_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;
 	*operation = psa_mac_operation_init();

 	return OT_ERROR_NONE;
 }

 otError otPlatCryptoHmacSha256Deinit(otCryptoContext *aContext)
 {
 	psa_mac_operation_t *operation;

 	if (!checkContext(aContext, sizeof(psa_mac_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_mac_abort(operation));
 }

 otError otPlatCryptoHmacSha256Start(otCryptoContext *aContext, const otCryptoKey *aKey)
 {
 	psa_mac_operation_t *operation;
 	psa_status_t status;

 	if (aKey == NULL || !checkContext(aContext, sizeof(psa_mac_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	ensureKeyIsLoaded(aKey->mKeyRef);
 	operation = aContext->mContext;
 	status = psa_mac_sign_setup(operation, aKey->mKeyRef, PSA_ALG_HMAC(PSA_ALG_SHA_256));

 	return psaToOtError(status);
 }

 otError otPlatCryptoHmacSha256Update(otCryptoContext *aContext,
 				     const void *aBuf,
 				     uint16_t aBufLength)
 {
 	psa_mac_operation_t *operation;

 	if (aBuf == NULL || !checkContext(aContext, sizeof(psa_mac_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_mac_update(operation, (const uint8_t *) aBuf, aBufLength));
 }

 otError otPlatCryptoHmacSha256Finish(otCryptoContext *aContext, uint8_t *aBuf, size_t aBufLength)
 {
 	psa_mac_operation_t *operation;
 	size_t mac_length;

 	if (aBuf == NULL || !checkContext(aContext, sizeof(psa_mac_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_mac_sign_finish(operation, aBuf, aBufLength, &mac_length));
 }

 otError otPlatCryptoAesInit(otCryptoContext *aContext)
 {
 	psa_key_id_t *key_ref;

 	if (!checkContext(aContext, sizeof(psa_key_id_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	key_ref = aContext->mContext;
 	*key_ref = (psa_key_id_t) 0; /* In TF-M 1.5.0 this can be replaced with PSA_KEY_ID_NULL */

 	return OT_ERROR_NONE;
 }

 otError otPlatCryptoAesSetKey(otCryptoContext *aContext, const otCryptoKey *aKey)
 {
 	psa_key_id_t *key_ref;

 	if (aKey == NULL || !checkContext(aContext, sizeof(psa_key_id_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	key_ref = aContext->mContext;
 	*key_ref = aKey->mKeyRef;

 	return OT_ERROR_NONE;
 }

 otError otPlatCryptoAesEncrypt(otCryptoContext *aContext, const uint8_t *aInput, uint8_t *aOutput)
 {
 	const size_t block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(PSA_KEY_TYPE_AES);
 	psa_status_t status = PSA_SUCCESS;
 	psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
 	psa_key_id_t *key_ref;
 	size_t cipher_length;

 	if (aInput == NULL || aOutput == NULL || !checkContext(aContext, sizeof(psa_key_id_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	/*
 	 * The code below can be simplified after updating TF-M version used in Zephyr to 1.5.0
 	 * (see upstream commit: 045ec4abfc73152a0116684ba9127d0a97cc8d34), using
 	 * psa_cipher_encrypt() function which will replace the setup-update-finish sequence below.
 	 */
 	key_ref = aContext->mContext;
 	ensureKeyIsLoaded(*key_ref);
 	status = psa_cipher_encrypt_setup(&operation, *key_ref, PSA_ALG_ECB_NO_PADDING);

 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	status = psa_cipher_update(&operation,
 				   aInput,
 				   block_size,
 				   aOutput,
 				   block_size,
 				   &cipher_length);

 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	status = psa_cipher_finish(&operation,
 				   aOutput + cipher_length,
 				   block_size - cipher_length,
 				   &cipher_length);

 out:
 	psa_cipher_abort(&operation);
 	return psaToOtError(status);
 }

 otError otPlatCryptoAesFree(otCryptoContext *aContext)
 {
 	return OT_ERROR_NONE;
 }

 otError otPlatCryptoSha256Init(otCryptoContext *aContext)
 {
 	psa_hash_operation_t *operation;

 	if (!checkContext(aContext, sizeof(psa_hash_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;
 	*operation = psa_hash_operation_init();

 	return OT_ERROR_NONE;
 }

 otError otPlatCryptoSha256Deinit(otCryptoContext *aContext)
 {
 	psa_hash_operation_t *operation;

 	if (!checkContext(aContext, sizeof(psa_hash_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_hash_abort(operation));
 }

 otError otPlatCryptoSha256Start(otCryptoContext *aContext)
 {
 	psa_hash_operation_t *operation;

 	if (!checkContext(aContext, sizeof(psa_hash_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_hash_setup(operation, PSA_ALG_SHA_256));
 }

 otError otPlatCryptoSha256Update(otCryptoContext *aContext, const void *aBuf, uint16_t aBufLength)
 {
 	psa_hash_operation_t *operation;

 	if (aBuf == NULL || !checkContext(aContext, sizeof(psa_hash_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_hash_update(operation, (const uint8_t *) aBuf, aBufLength));
 }

 otError otPlatCryptoSha256Finish(otCryptoContext *aContext, uint8_t *aHash, uint16_t aHashSize)
 {
 	psa_hash_operation_t *operation;
 	size_t hash_size;

 	if (aHash == NULL || !checkContext(aContext, sizeof(psa_hash_operation_t))) {
 		return OT_ERROR_INVALID_ARGS;
 	}

 	operation = aContext->mContext;

 	return psaToOtError(psa_hash_finish(operation, aHash, aHashSize, &hash_size));
 }

 void otPlatCryptoRandomInit(void)
 {
 }

 void otPlatCryptoRandomDeinit(void)
 {
 }

 otError otPlatCryptoRandomGet(uint8_t *aBuffer, uint16_t aSize)
 {
 	return psaToOtError(psa_generate_random(aBuffer, aSize));
 }

 #if defined(CONFIG_OPENTHREAD_ECDSA)

 otError otPlatCryptoEcdsaGenerateKey(otPlatCryptoEcdsaKeyPair *aKeyPair)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_key_id_t key_id = 0;
 	psa_status_t status;
 	size_t exported_length;

 	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_EXPORT);
 	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
 	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
 	psa_set_key_bits(&attributes, 256);

 	status = psa_generate_key(&attributes, &key_id);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	status = psa_export_key(key_id, aKeyPair->mDerBytes, OT_CRYPTO_ECDSA_MAX_DER_SIZE,
 				&exported_length);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}
 	aKeyPair->mDerLength = exported_length;

 out:
 	psa_reset_key_attributes(&attributes);
 	psa_destroy_key(key_id);

 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaGetPublicKey(const otPlatCryptoEcdsaKeyPair *aKeyPair,
 				      otPlatCryptoEcdsaPublicKey *aPublicKey)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_key_id_t key_id = 0;
 	psa_status_t status;
 	size_t exported_length;
 	uint8_t buffer[1 + OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE];

 	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
 	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
 	psa_set_key_bits(&attributes, 256);

 	status = psa_import_key(&attributes, aKeyPair->mDerBytes, aKeyPair->mDerLength, &key_id);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	status = psa_export_public_key(key_id, buffer, sizeof(buffer), &exported_length);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}
 	__ASSERT_NO_MSG(exported_length == sizeof(buffer));
 	memcpy(aPublicKey->m8, buffer + 1, OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE);

 out:
 	psa_reset_key_attributes(&attributes);
 	psa_destroy_key(key_id);

 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaSign(const otPlatCryptoEcdsaKeyPair *aKeyPair,
 			      const otPlatCryptoSha256Hash *aHash,
 			      otPlatCryptoEcdsaSignature *aSignature)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_key_id_t key_id;
 	psa_status_t status;
 	size_t signature_length;

 	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_HASH);
 	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
 	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
 	psa_set_key_bits(&attributes, 256);

 	status = psa_import_key(&attributes, aKeyPair->mDerBytes, aKeyPair->mDerLength, &key_id);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	status = psa_sign_hash(key_id, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
 			       OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
 			       OT_CRYPTO_ECDSA_SIGNATURE_SIZE, &signature_length);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 out:
 	psa_reset_key_attributes(&attributes);
 	psa_destroy_key(key_id);

 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaVerify(const otPlatCryptoEcdsaPublicKey *aPublicKey,
 				const otPlatCryptoSha256Hash *aHash,
 				const otPlatCryptoEcdsaSignature *aSignature)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_key_id_t key_id;
 	psa_status_t status;
 	uint8_t buffer[1 + OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE];

 	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_HASH);
 	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
 	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_FAMILY_SECP_R1));
 	psa_set_key_bits(&attributes, 256);

 	/*
 	 * `psa_import_key` expects a key format as specified by SEC1 &sect;2.3.3 for the
 	 * uncompressed representation of the ECPoint.
 	 */
 	buffer[0] = 0x04;
 	memcpy(buffer + 1, aPublicKey->m8, OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE);
 	status = psa_import_key(&attributes, buffer, sizeof(buffer), &key_id);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	status = psa_verify_hash(key_id, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
 				 OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
 				 OT_CRYPTO_ECDSA_SIGNATURE_SIZE);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 out:
 	psa_reset_key_attributes(&attributes);
 	psa_destroy_key(key_id);

 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaSignUsingKeyRef(otCryptoKeyRef aKeyRef,
 					 const otPlatCryptoSha256Hash *aHash,
 					 otPlatCryptoEcdsaSignature *aSignature)
 {
 	psa_status_t status;
 	size_t signature_length;

 	status = psa_sign_hash(aKeyRef, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
 			       OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
 			       OT_CRYPTO_ECDSA_SIGNATURE_SIZE, &signature_length);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	__ASSERT_NO_MSG(signature_length == OT_CRYPTO_ECDSA_SIGNATURE_SIZE);
 out:
 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaVerifyUsingKeyRef(otCryptoKeyRef aKeyRef,
 					   const otPlatCryptoSha256Hash *aHash,
 					   const otPlatCryptoEcdsaSignature *aSignature)
 {
 	psa_status_t status;

 	status = psa_verify_hash(aKeyRef, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
 				 OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
 				 OT_CRYPTO_ECDSA_SIGNATURE_SIZE);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 out:
 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaExportPublicKey(otCryptoKeyRef aKeyRef,
 					 otPlatCryptoEcdsaPublicKey *aPublicKey)
 {
 	psa_status_t status;
 	size_t exported_length;
 	uint8_t buffer[1 + OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE];

 	status = psa_export_public_key(aKeyRef, buffer, sizeof(buffer), &exported_length);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 	__ASSERT_NO_MSG(exported_length == sizeof(buffer));
 	memcpy(aPublicKey->m8, buffer + 1, OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE);

 out:
 	return psaToOtError(status);
 }

 otError otPlatCryptoEcdsaGenerateAndImportKey(otCryptoKeyRef aKeyRef)
 {
 	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 	psa_status_t status;
 	psa_key_id_t key_id = (psa_key_id_t)aKeyRef;

 	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_HASH | PSA_KEY_USAGE_SIGN_HASH);
 	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
 	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
 	psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_PERSISTENT);
 	psa_set_key_id(&attributes, key_id);
 	psa_set_key_bits(&attributes, 256);

 	status = psa_generate_key(&attributes, &key_id);
 	if (status != PSA_SUCCESS) {
 		goto out;
 	}

 out:
 	psa_reset_key_attributes(&attributes);

 	return psaToOtError(status);
 }

 #endif /* #if CONFIG_OPENTHREAD_ECDSA */
	/*
	* Copyright (c) 2021 Nordic Semiconductor ASA
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#include <openthread/platform/crypto.h>

	#include <psa/crypto.h>

	#if defined(CONFIG_OPENTHREAD_ECDSA)
	#include <string.h>
	#include <zephyr/sys/__assert.h>
	#endif

	static otError psaToOtError(psa_status_t aStatus)
	{
	switch (aStatus) {
	case PSA_SUCCESS:
	return OT_ERROR_NONE;
	case PSA_ERROR_INVALID_ARGUMENT:
	return OT_ERROR_INVALID_ARGS;
	case PSA_ERROR_BUFFER_TOO_SMALL:
	return OT_ERROR_NO_BUFS;
	default:
	return OT_ERROR_FAILED;
	}
	}

	static psa_key_type_t toPsaKeyType(otCryptoKeyType aType)
	{
	switch (aType) {
	case OT_CRYPTO_KEY_TYPE_RAW:
	return PSA_KEY_TYPE_RAW_DATA;
	case OT_CRYPTO_KEY_TYPE_AES:
	return PSA_KEY_TYPE_AES;
	case OT_CRYPTO_KEY_TYPE_HMAC:
	return PSA_KEY_TYPE_HMAC;
	default:
	return PSA_KEY_TYPE_NONE;
	}
	}

	static psa_algorithm_t toPsaAlgorithm(otCryptoKeyAlgorithm aAlgorithm)
	{
	switch (aAlgorithm) {
	case OT_CRYPTO_KEY_ALG_AES_ECB:
	return PSA_ALG_ECB_NO_PADDING;
	case OT_CRYPTO_KEY_ALG_HMAC_SHA_256:
	return PSA_ALG_HMAC(PSA_ALG_SHA_256);
	default:
	/*
	* There is currently no constant like PSA_ALG_NONE, but 0 is used
	* to indicate an unknown algorithm.
	*/
	return (psa_algorithm_t) 0;
	}
	}

	static psa_key_usage_t toPsaKeyUsage(int aUsage)
	{
	psa_key_usage_t usage = 0;

	if (aUsage & OT_CRYPTO_KEY_USAGE_EXPORT) {
	usage \|= PSA_KEY_USAGE_EXPORT;
	}

	if (aUsage & OT_CRYPTO_KEY_USAGE_ENCRYPT) {
	usage \|= PSA_KEY_USAGE_ENCRYPT;
	}

	if (aUsage & OT_CRYPTO_KEY_USAGE_DECRYPT) {
	usage \|= PSA_KEY_USAGE_DECRYPT;
	}

	if (aUsage & OT_CRYPTO_KEY_USAGE_SIGN_HASH) {
	usage \|= PSA_KEY_USAGE_SIGN_HASH;
	}

	return usage;
	}

	static bool checkKeyUsage(int aUsage)
	{
	/* Check if only supported flags have been passed */
	int supported_flags = OT_CRYPTO_KEY_USAGE_EXPORT \|
	OT_CRYPTO_KEY_USAGE_ENCRYPT \|
	OT_CRYPTO_KEY_USAGE_DECRYPT \|
	OT_CRYPTO_KEY_USAGE_SIGN_HASH;

	return (aUsage & ~supported_flags) == 0;
	}

	static bool checkContext(otCryptoContext *aContext, size_t aMinSize)
	{
	/* Verify that the passed context is initialized and points to a big enough buffer */
	return aContext != NULL && aContext->mContext != NULL && aContext->mContextSize >= aMinSize;
	}

	static void ensureKeyIsLoaded(otCryptoKeyRef aKeyRef)
	{
	/*
	* The workaround below will no longer be need after updating TF-M version used in Zephyr
	* to 1.5.0 (see upstream commit 42e77b561fcfe19819ff1e63cb7c0b672ee8ba41).
	* In the recent versions of TF-M the concept of key handles and psa_open_key()/
	* psa_close_key() APIs have been being deprecated, but the version currently used in Zephyr
	* is in the middle of that transition. Consequently, psa_destroy_key() and lots of other
	* functions will fail when a key ID that they take as a parameter is not loaded from the
	* persistent storage. That may occur when a given persistent key is created via
	* psa_generate_key() or psa_import_key(), and then the device reboots.
	*
	* Use psa_open_key() when the key has not been loaded yet to work around the issue.
	*/
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_status_t status = psa_get_key_attributes(aKeyRef, &attributes);
	psa_key_id_t key_handle;

	if (status == PSA_ERROR_INVALID_HANDLE) {
	psa_open_key(aKeyRef, &key_handle);
	}

	psa_reset_key_attributes(&attributes);
	}

	void otPlatCryptoInit(void)
	{
	psa_crypto_init();
	}

	otError otPlatCryptoImportKey(otCryptoKeyRef *aKeyRef,
	otCryptoKeyType aKeyType,
	otCryptoKeyAlgorithm aKeyAlgorithm,
	int aKeyUsage,
	otCryptoKeyStorage aKeyPersistence,
	const uint8_t *aKey,
	size_t aKeyLen)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_status_t status;

	if (aKeyRef == NULL \|\| aKey == NULL \|\| !checkKeyUsage(aKeyUsage)) {
	return OT_ERROR_INVALID_ARGS;
	}

	psa_set_key_type(&attributes, toPsaKeyType(aKeyType));
	psa_set_key_algorithm(&attributes, toPsaAlgorithm(aKeyAlgorithm));
	psa_set_key_usage_flags(&attributes, toPsaKeyUsage(aKeyUsage));

	switch (aKeyPersistence) {
	case OT_CRYPTO_KEY_STORAGE_PERSISTENT:
	psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_PERSISTENT);
	psa_set_key_id(&attributes, *aKeyRef);
	break;
	case OT_CRYPTO_KEY_STORAGE_VOLATILE:
	psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_VOLATILE);
	break;
	}

	status = psa_import_key(&attributes, aKey, aKeyLen, aKeyRef);
	psa_reset_key_attributes(&attributes);

	return psaToOtError(status);
	}

	otError otPlatCryptoExportKey(otCryptoKeyRef aKeyRef,
	uint8_t *aBuffer,
	size_t aBufferLen,
	size_t *aKeyLen)
	{
	if (aBuffer == NULL) {
	return OT_ERROR_INVALID_ARGS;
	}

	ensureKeyIsLoaded(aKeyRef);

	return psaToOtError(psa_export_key(aKeyRef, aBuffer, aBufferLen, aKeyLen));
	}

	otError otPlatCryptoDestroyKey(otCryptoKeyRef aKeyRef)
	{
	ensureKeyIsLoaded(aKeyRef);

	return psaToOtError(psa_destroy_key(aKeyRef));
	}

	bool otPlatCryptoHasKey(otCryptoKeyRef aKeyRef)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_status_t status;

	ensureKeyIsLoaded(aKeyRef);
	status = psa_get_key_attributes(aKeyRef, &attributes);
	psa_reset_key_attributes(&attributes);

	return status == PSA_SUCCESS;
	}

	otError otPlatCryptoHmacSha256Init(otCryptoContext *aContext)
	{
	psa_mac_operation_t *operation;

	if (!checkContext(aContext, sizeof(psa_mac_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;
	*operation = psa_mac_operation_init();

	return OT_ERROR_NONE;
	}

	otError otPlatCryptoHmacSha256Deinit(otCryptoContext *aContext)
	{
	psa_mac_operation_t *operation;

	if (!checkContext(aContext, sizeof(psa_mac_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_mac_abort(operation));
	}

	otError otPlatCryptoHmacSha256Start(otCryptoContext aContext, const otCryptoKey aKey)
	{
	psa_mac_operation_t *operation;
	psa_status_t status;

	if (aKey == NULL \|\| !checkContext(aContext, sizeof(psa_mac_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	ensureKeyIsLoaded(aKey->mKeyRef);
	operation = aContext->mContext;
	status = psa_mac_sign_setup(operation, aKey->mKeyRef, PSA_ALG_HMAC(PSA_ALG_SHA_256));

	return psaToOtError(status);
	}

	otError otPlatCryptoHmacSha256Update(otCryptoContext *aContext,
	const void *aBuf,
	uint16_t aBufLength)
	{
	psa_mac_operation_t *operation;

	if (aBuf == NULL \|\| !checkContext(aContext, sizeof(psa_mac_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_mac_update(operation, (const uint8_t *) aBuf, aBufLength));
	}

	otError otPlatCryptoHmacSha256Finish(otCryptoContext aContext, uint8_t aBuf, size_t aBufLength)
	{
	psa_mac_operation_t *operation;
	size_t mac_length;

	if (aBuf == NULL \|\| !checkContext(aContext, sizeof(psa_mac_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_mac_sign_finish(operation, aBuf, aBufLength, &mac_length));
	}

	otError otPlatCryptoAesInit(otCryptoContext *aContext)
	{
	psa_key_id_t *key_ref;

	if (!checkContext(aContext, sizeof(psa_key_id_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	key_ref = aContext->mContext;
	key_ref = (psa_key_id_t) 0; / In TF-M 1.5.0 this can be replaced with PSA_KEY_ID_NULL */

	return OT_ERROR_NONE;
	}

	otError otPlatCryptoAesSetKey(otCryptoContext aContext, const otCryptoKey aKey)
	{
	psa_key_id_t *key_ref;

	if (aKey == NULL \|\| !checkContext(aContext, sizeof(psa_key_id_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	key_ref = aContext->mContext;
	*key_ref = aKey->mKeyRef;

	return OT_ERROR_NONE;
	}

	otError otPlatCryptoAesEncrypt(otCryptoContext aContext, const uint8_t aInput, uint8_t *aOutput)
	{
	const size_t block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(PSA_KEY_TYPE_AES);
	psa_status_t status = PSA_SUCCESS;
	psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
	psa_key_id_t *key_ref;
	size_t cipher_length;

	if (aInput == NULL \|\| aOutput == NULL \|\| !checkContext(aContext, sizeof(psa_key_id_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	/*
	* The code below can be simplified after updating TF-M version used in Zephyr to 1.5.0
	* (see upstream commit: 045ec4abfc73152a0116684ba9127d0a97cc8d34), using
	* psa_cipher_encrypt() function which will replace the setup-update-finish sequence below.
	*/
	key_ref = aContext->mContext;
	ensureKeyIsLoaded(*key_ref);
	status = psa_cipher_encrypt_setup(&operation, *key_ref, PSA_ALG_ECB_NO_PADDING);

	if (status != PSA_SUCCESS) {
	goto out;
	}

	status = psa_cipher_update(&operation,
	aInput,
	block_size,
	aOutput,
	block_size,
	&cipher_length);

	if (status != PSA_SUCCESS) {
	goto out;
	}

	status = psa_cipher_finish(&operation,
	aOutput + cipher_length,
	block_size - cipher_length,
	&cipher_length);

	out:
	psa_cipher_abort(&operation);
	return psaToOtError(status);
	}

	otError otPlatCryptoAesFree(otCryptoContext *aContext)
	{
	return OT_ERROR_NONE;
	}

	otError otPlatCryptoSha256Init(otCryptoContext *aContext)
	{
	psa_hash_operation_t *operation;

	if (!checkContext(aContext, sizeof(psa_hash_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;
	*operation = psa_hash_operation_init();

	return OT_ERROR_NONE;
	}

	otError otPlatCryptoSha256Deinit(otCryptoContext *aContext)
	{
	psa_hash_operation_t *operation;

	if (!checkContext(aContext, sizeof(psa_hash_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_hash_abort(operation));
	}

	otError otPlatCryptoSha256Start(otCryptoContext *aContext)
	{
	psa_hash_operation_t *operation;

	if (!checkContext(aContext, sizeof(psa_hash_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_hash_setup(operation, PSA_ALG_SHA_256));
	}

	otError otPlatCryptoSha256Update(otCryptoContext aContext, const void aBuf, uint16_t aBufLength)
	{
	psa_hash_operation_t *operation;

	if (aBuf == NULL \|\| !checkContext(aContext, sizeof(psa_hash_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_hash_update(operation, (const uint8_t *) aBuf, aBufLength));
	}

	otError otPlatCryptoSha256Finish(otCryptoContext aContext, uint8_t aHash, uint16_t aHashSize)
	{
	psa_hash_operation_t *operation;
	size_t hash_size;

	if (aHash == NULL \|\| !checkContext(aContext, sizeof(psa_hash_operation_t))) {
	return OT_ERROR_INVALID_ARGS;
	}

	operation = aContext->mContext;

	return psaToOtError(psa_hash_finish(operation, aHash, aHashSize, &hash_size));
	}

	void otPlatCryptoRandomInit(void)
	{
	}

	void otPlatCryptoRandomDeinit(void)
	{
	}

	otError otPlatCryptoRandomGet(uint8_t *aBuffer, uint16_t aSize)
	{
	return psaToOtError(psa_generate_random(aBuffer, aSize));
	}

	#if defined(CONFIG_OPENTHREAD_ECDSA)

	otError otPlatCryptoEcdsaGenerateKey(otPlatCryptoEcdsaKeyPair *aKeyPair)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_key_id_t key_id = 0;
	psa_status_t status;
	size_t exported_length;

	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_EXPORT);
	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_bits(&attributes, 256);

	status = psa_generate_key(&attributes, &key_id);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	status = psa_export_key(key_id, aKeyPair->mDerBytes, OT_CRYPTO_ECDSA_MAX_DER_SIZE,
	&exported_length);
	if (status != PSA_SUCCESS) {
	goto out;
	}
	aKeyPair->mDerLength = exported_length;

	out:
	psa_reset_key_attributes(&attributes);
	psa_destroy_key(key_id);

	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaGetPublicKey(const otPlatCryptoEcdsaKeyPair *aKeyPair,
	otPlatCryptoEcdsaPublicKey *aPublicKey)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_key_id_t key_id = 0;
	psa_status_t status;
	size_t exported_length;
	uint8_t buffer[1 + OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE];

	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_bits(&attributes, 256);

	status = psa_import_key(&attributes, aKeyPair->mDerBytes, aKeyPair->mDerLength, &key_id);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	status = psa_export_public_key(key_id, buffer, sizeof(buffer), &exported_length);
	if (status != PSA_SUCCESS) {
	goto out;
	}
	__ASSERT_NO_MSG(exported_length == sizeof(buffer));
	memcpy(aPublicKey->m8, buffer + 1, OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE);

	out:
	psa_reset_key_attributes(&attributes);
	psa_destroy_key(key_id);

	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaSign(const otPlatCryptoEcdsaKeyPair *aKeyPair,
	const otPlatCryptoSha256Hash *aHash,
	otPlatCryptoEcdsaSignature *aSignature)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_key_id_t key_id;
	psa_status_t status;
	size_t signature_length;

	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_SIGN_HASH);
	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_bits(&attributes, 256);

	status = psa_import_key(&attributes, aKeyPair->mDerBytes, aKeyPair->mDerLength, &key_id);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	status = psa_sign_hash(key_id, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
	OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
	OT_CRYPTO_ECDSA_SIGNATURE_SIZE, &signature_length);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	out:
	psa_reset_key_attributes(&attributes);
	psa_destroy_key(key_id);

	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaVerify(const otPlatCryptoEcdsaPublicKey *aPublicKey,
	const otPlatCryptoSha256Hash *aHash,
	const otPlatCryptoEcdsaSignature *aSignature)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_key_id_t key_id;
	psa_status_t status;
	uint8_t buffer[1 + OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE];

	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_HASH);
	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_bits(&attributes, 256);

	/*
	* `psa_import_key` expects a key format as specified by SEC1 §2.3.3 for the
	* uncompressed representation of the ECPoint.
	*/
	buffer[0] = 0x04;
	memcpy(buffer + 1, aPublicKey->m8, OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE);
	status = psa_import_key(&attributes, buffer, sizeof(buffer), &key_id);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	status = psa_verify_hash(key_id, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
	OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
	OT_CRYPTO_ECDSA_SIGNATURE_SIZE);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	out:
	psa_reset_key_attributes(&attributes);
	psa_destroy_key(key_id);

	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaSignUsingKeyRef(otCryptoKeyRef aKeyRef,
	const otPlatCryptoSha256Hash *aHash,
	otPlatCryptoEcdsaSignature *aSignature)
	{
	psa_status_t status;
	size_t signature_length;

	status = psa_sign_hash(aKeyRef, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
	OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
	OT_CRYPTO_ECDSA_SIGNATURE_SIZE, &signature_length);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	__ASSERT_NO_MSG(signature_length == OT_CRYPTO_ECDSA_SIGNATURE_SIZE);
	out:
	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaVerifyUsingKeyRef(otCryptoKeyRef aKeyRef,
	const otPlatCryptoSha256Hash *aHash,
	const otPlatCryptoEcdsaSignature *aSignature)
	{
	psa_status_t status;

	status = psa_verify_hash(aKeyRef, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256), aHash->m8,
	OT_CRYPTO_SHA256_HASH_SIZE, aSignature->m8,
	OT_CRYPTO_ECDSA_SIGNATURE_SIZE);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	out:
	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaExportPublicKey(otCryptoKeyRef aKeyRef,
	otPlatCryptoEcdsaPublicKey *aPublicKey)
	{
	psa_status_t status;
	size_t exported_length;
	uint8_t buffer[1 + OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE];

	status = psa_export_public_key(aKeyRef, buffer, sizeof(buffer), &exported_length);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	__ASSERT_NO_MSG(exported_length == sizeof(buffer));
	memcpy(aPublicKey->m8, buffer + 1, OT_CRYPTO_ECDSA_PUBLIC_KEY_SIZE);

	out:
	return psaToOtError(status);
	}

	otError otPlatCryptoEcdsaGenerateAndImportKey(otCryptoKeyRef aKeyRef)
	{
	psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
	psa_status_t status;
	psa_key_id_t key_id = (psa_key_id_t)aKeyRef;

	psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_VERIFY_HASH \| PSA_KEY_USAGE_SIGN_HASH);
	psa_set_key_algorithm(&attributes, PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256));
	psa_set_key_type(&attributes, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_lifetime(&attributes, PSA_KEY_LIFETIME_PERSISTENT);
	psa_set_key_id(&attributes, key_id);
	psa_set_key_bits(&attributes, 256);

	status = psa_generate_key(&attributes, &key_id);
	if (status != PSA_SUCCESS) {
	goto out;
	}

	out:
	psa_reset_key_attributes(&attributes);

	return psaToOtError(status);
	}

	#endif /* #if CONFIG_OPENTHREAD_ECDSA */