src/platform/silabs/efr32/Efr32PsaOpaqueKeypair.cpp - third_party/github/project-chip/connectedhomeip - Git at Google

 /*
  *    Copyright (c) 2022 Project CHIP Authors
  *    All rights reserved.
  *
  *    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.
  */

 #include "Efr32OpaqueKeypair.h"
 #include "em_device.h"
 #include <psa/crypto.h>

 #include <lib/core/CHIPSafeCasts.h>
 #include <lib/support/CHIPMem.h>
 #include <lib/support/SafeInt.h>
 using chip::Platform::MemoryCalloc;
 using chip::Platform::MemoryFree;

 using chip::Crypto::P256ECDHDerivedSecret;
 using chip::Crypto::P256ECDSASignature;
 using chip::Crypto::P256Keypair;
 using chip::Crypto::P256PublicKey;
 using chip::Crypto::P256SerializedKeypair;

 namespace chip {
 namespace DeviceLayer {
 namespace Internal {

 /*******************************************************************************
  *
  * PSA key ID range for storing Matter Opaque keys
  *
  ******************************************************************************/
 #define PSA_KEY_ID_FOR_MATTER_MIN (0x00004400)
 #define PSA_KEY_ID_FOR_MATTER_MAX (0x000045FF)
 #define PSA_KEY_ID_FOR_MATTER_SIZE (PSA_KEY_ID_FOR_MATTER_MAX - PSA_KEY_ID_FOR_MATTER_MIN + 1)

 static_assert((kEFR32OpaqueKeyIdPersistentMax - kEFR32OpaqueKeyIdPersistentMin) < PSA_KEY_ID_FOR_MATTER_SIZE,
               "Not enough PSA range to store all allowed opaque key IDs");

 #if defined(SEMAILBOX_PRESENT) && (_SILICON_LABS_SECURITY_FEATURE == _SILICON_LABS_SECURITY_FEATURE_VAULT)
 #define PSA_CRYPTO_LOCATION_FOR_DEVICE PSA_KEY_LOCATION_SL_SE_OPAQUE
 #elif defined(CRYPTOACC_PRESENT) && defined(SEPUF_PRESENT) && defined(SL_TRUSTZONE_NONSECURE)
 #define PSA_CRYPTO_LOCATION_FOR_DEVICE PSA_KEY_LOCATION_SL_CRYPTOACC_OPAQUE
 #else
 #define PSA_CRYPTO_LOCATION_FOR_DEVICE PSA_KEY_LOCATION_LOCAL_STORAGE
 #endif

 static void _log_PSA_error(psa_status_t status)
 {
     if (status != PSA_SUCCESS)
     {
         ChipLogError(Crypto, "PSA error: %ld", status);
     }
 }

 /*******************************************************************************
  *
  * PSA Crypto backed implementation of EFR32OpaqueKeypair
  *
  ******************************************************************************/

 static bool is_opaque_key_valid(EFR32OpaqueKeyId id)
 {
     if (id == kEFR32OpaqueKeyIdVolatile)
     {
         return true;
     }
     else if (id >= kEFR32OpaqueKeyIdPersistentMin && id <= (kEFR32OpaqueKeyIdPersistentMin + PSA_KEY_ID_FOR_MATTER_SIZE))
     {
         return true;
     }

     return false;
 }

 static mbedtls_svc_key_id_t psa_key_id_from_opaque(EFR32OpaqueKeyId id)
 {
     if (id == kEFR32OpaqueKeyIdVolatile || !is_opaque_key_valid(id))
     {
         return 0;
     }

     return PSA_KEY_ID_FOR_MATTER_MIN + (id - kEFR32OpaqueKeyIdPersistentMin);
 }

 static EFR32OpaqueKeyId opaque_key_id_from_psa(mbedtls_svc_key_id_t id)
 {
     if (id == 0)
     {
         return kEFR32OpaqueKeyIdVolatile;
     }
     else if (id >= PSA_KEY_ID_FOR_MATTER_MIN && id <= PSA_KEY_ID_FOR_MATTER_MAX)
     {
         return (id + kEFR32OpaqueKeyIdPersistentMin) - PSA_KEY_ID_FOR_MATTER_MIN;
     }
     else
     {
         return kEFR32OpaqueKeyIdUnknown;
     }
 }

 EFR32OpaqueKeypair::EFR32OpaqueKeypair()
 {
     psa_crypto_init();
     // Avoid having a reference to PSA datatypes in the signature of this class
     mContext = MemoryCalloc(1, sizeof(mbedtls_svc_key_id_t));
 }

 EFR32OpaqueKeypair::~EFR32OpaqueKeypair()
 {
     // Free key resources
     if (mContext != nullptr)
     {
         // Delete volatile keys, since nobody else can after we drop the key ID.
         if (!mIsPersistent)
         {
             DestroyKey();
         }

         MemoryFree(mContext);
         mContext = nullptr;
     }
 }

 CHIP_ERROR EFR32OpaqueKeypair::Load(EFR32OpaqueKeyId opaque_id)
 {
     CHIP_ERROR error            = CHIP_NO_ERROR;
     psa_status_t status         = PSA_ERROR_BAD_STATE;
     mbedtls_svc_key_id_t key_id = 0;

     VerifyOrExit(opaque_id != kEFR32OpaqueKeyIdVolatile, error = CHIP_ERROR_INVALID_ARGUMENT);
     VerifyOrExit(is_opaque_key_valid(opaque_id), error = CHIP_ERROR_INVALID_ARGUMENT);
     VerifyOrExit(mContext, error = CHIP_ERROR_INCORRECT_STATE);

     // If the object contains a volatile key, clean it up before reusing the object storage
     if (mHasKey && !mIsPersistent)
     {
         DestroyKey();
     }

     key_id = psa_key_id_from_opaque(opaque_id);

     status = psa_export_public_key(key_id, mPubkeyRef, mPubkeySize, &mPubkeyLength);

     if (status == PSA_ERROR_DOES_NOT_EXIST)
     {
         error = CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND;
         goto exit;
     }

     VerifyOrExit(status == PSA_SUCCESS, {
         _log_PSA_error(status);
         error = CHIP_ERROR_INTERNAL;
     });

     // Store the key ID and mark the key as valid
     *(mbedtls_svc_key_id_t *) mContext = key_id;
     mHasKey                            = true;
     mIsPersistent                      = true;

 exit:
     if (error != CHIP_NO_ERROR)
     {
         memset(mPubkeyRef, 0, mPubkeySize);
     }

     return error;
 }

 CHIP_ERROR EFR32OpaqueKeypair::Create(EFR32OpaqueKeyId opaque_id, EFR32OpaqueKeyUsages usage)
 {
     CHIP_ERROR error            = CHIP_NO_ERROR;
     psa_status_t status         = PSA_ERROR_BAD_STATE;
     psa_key_attributes_t attr   = PSA_KEY_ATTRIBUTES_INIT;
     mbedtls_svc_key_id_t key_id = 0;

     VerifyOrExit(is_opaque_key_valid(opaque_id), error = CHIP_ERROR_INVALID_ARGUMENT);
     VerifyOrExit(mContext, error = CHIP_ERROR_INCORRECT_STATE);

     if (opaque_id == kEFR32OpaqueKeyIdVolatile)
     {
         psa_set_key_lifetime(
             &attr, PSA_KEY_LIFETIME_FROM_PERSISTENCE_AND_LOCATION(PSA_KEY_LIFETIME_VOLATILE, PSA_CRYPTO_LOCATION_FOR_DEVICE));
     }
     else
     {
         psa_key_handle_t key_handle;

         key_id = psa_key_id_from_opaque(opaque_id);

         // Check if the key already exists
         int ret = psa_open_key(key_id, &key_handle);
         if (PSA_SUCCESS == ret)
         {
             // WARNING: Existing key! This is caused by a problem in the key store.
             // The key must be destroyed, otherwhise the device won't recover.
             ChipLogError(Crypto, "WARNING: PSA key recycled: %d / %ld", opaque_id, key_id);
             psa_destroy_key(key_id);
         }

         psa_set_key_id(&attr, key_id);
         psa_set_key_lifetime(
             &attr, PSA_KEY_LIFETIME_FROM_PERSISTENCE_AND_LOCATION(PSA_KEY_LIFETIME_PERSISTENT, PSA_CRYPTO_LOCATION_FOR_DEVICE));
     }

     switch (usage)
     {
     case EFR32OpaqueKeyUsages::ECDSA_P256_SHA256:
         psa_set_key_type(&attr, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
         psa_set_key_bits(&attr, 256);
         psa_set_key_algorithm(&attr, PSA_ALG_ECDSA(PSA_ALG_SHA_256));
         // Need hash signing permissions because the CSR generation uses sign_hash internally
         psa_set_key_usage_flags(&attr, PSA_KEY_USAGE_SIGN_MESSAGE | PSA_KEY_USAGE_SIGN_HASH);
         break;
     case EFR32OpaqueKeyUsages::ECDH_P256:
         psa_set_key_type(&attr, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
         psa_set_key_bits(&attr, 256);
         psa_set_key_algorithm(&attr, PSA_ALG_ECDH);
         psa_set_key_usage_flags(&attr, PSA_KEY_USAGE_DERIVE);
         break;
     }

     status = psa_generate_key(&attr, &key_id);
     VerifyOrExit(status == PSA_SUCCESS, {
         _log_PSA_error(status);
         error = CHIP_ERROR_INTERNAL;
     });

     // Export the public key
     status = psa_export_public_key(key_id, mPubkeyRef, mPubkeySize, &mPubkeyLength);
     if (PSA_SUCCESS != status)
     {
         _log_PSA_error(status);
         // Key generation succeeded, but pubkey export did not. To avoid
         // memory leaks, delete the generated key before returning the error
         psa_destroy_key(key_id);
         error = CHIP_ERROR_INTERNAL;
         goto exit;
     }

     // Store the key ID and mark the key as valid
     mHasKey       = true;
     mIsPersistent = opaque_id != kEFR32OpaqueKeyIdVolatile;

 exit:
     psa_reset_key_attributes(&attr);
     if (mContext)
     {
         if (CHIP_NO_ERROR == error)
         {
             *(mbedtls_svc_key_id_t *) mContext = key_id;
         }
         else
         {
             *(mbedtls_svc_key_id_t *) mContext = 0;
         }
     }
     return error;
 }

 CHIP_ERROR EFR32OpaqueKeypair::GetPublicKey(uint8_t * output, size_t output_size, size_t * output_length) const
 {
     CHIP_ERROR error = CHIP_NO_ERROR;
     VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

     if (output_size >= mPubkeyLength)
     {
         memcpy(output, mPubkeyRef, mPubkeyLength);
         *output_length = mPubkeyLength;
     }
     else
     {
         error = CHIP_ERROR_BUFFER_TOO_SMALL;
     }
 exit:
     return error;
 }

 EFR32OpaqueKeyId EFR32OpaqueKeypair::GetKeyId() const
 {
     if (!mHasKey)
     {
         return kEFR32OpaqueKeyIdUnknown;
     }

     if (!mIsPersistent)
     {
         return kEFR32OpaqueKeyIdVolatile;
     }

     return opaque_key_id_from_psa(*(mbedtls_svc_key_id_t *) mContext);
 }

 CHIP_ERROR EFR32OpaqueKeypair::Sign(const uint8_t * msg, size_t msg_len, uint8_t * output, size_t output_size,
                                     size_t * output_length) const
 {
     CHIP_ERROR error    = CHIP_NO_ERROR;
     psa_status_t status = PSA_ERROR_BAD_STATE;

     VerifyOrExit(mContext, error = CHIP_ERROR_INCORRECT_STATE);
     VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

     status = psa_sign_message(*(mbedtls_svc_key_id_t *) mContext, PSA_ALG_ECDSA(PSA_ALG_SHA_256), msg, msg_len, output, output_size,
                               output_length);

     VerifyOrExit(status == PSA_SUCCESS, {
         _log_PSA_error(status);
         error = CHIP_ERROR_INTERNAL;
     });

 exit:
     return error;
 }

 CHIP_ERROR EFR32OpaqueKeypair::Derive(const uint8_t * their_key, size_t their_key_len, uint8_t * output, size_t output_size,
                                       size_t * output_length) const
 {
     CHIP_ERROR error    = CHIP_NO_ERROR;
     psa_status_t status = PSA_ERROR_BAD_STATE;

     VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

     status = psa_raw_key_agreement(PSA_ALG_ECDH, *(mbedtls_svc_key_id_t *) mContext, their_key, their_key_len, output, output_size,
                                    output_length);

     VerifyOrExit(status == PSA_SUCCESS, {
         _log_PSA_error(status);
         error = CHIP_ERROR_INTERNAL;
     });

 exit:
     return error;
 }

 CHIP_ERROR EFR32OpaqueKeypair::DestroyKey()
 {
     CHIP_ERROR error    = CHIP_NO_ERROR;
     psa_status_t status = PSA_ERROR_BAD_STATE;

     VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

     status = psa_destroy_key(*(mbedtls_svc_key_id_t *) mContext);
     VerifyOrExit(status == PSA_SUCCESS, {
         _log_PSA_error(status);
         error = CHIP_ERROR_INTERNAL;
     });

 exit:
     mHasKey       = false;
     mIsPersistent = false;
     memset(mPubkeyRef, 0, mPubkeySize);
     if (mContext)
     {
         *(mbedtls_svc_key_id_t *) mContext = 0;
     }
     return error;
 }

 /*******************************************************************************
  *
  * PSA Crypto backed implementation of EFR32OpaqueP256Keypair
  *
  ******************************************************************************/
 EFR32OpaqueP256Keypair::EFR32OpaqueP256Keypair()
 {
     mPubkeyRef    = mPubKey.Bytes();
     mPubkeySize   = mPubKey.Length();
     mPubkeyLength = 0;
 }

 EFR32OpaqueP256Keypair::~EFR32OpaqueP256Keypair() {}

 CHIP_ERROR EFR32OpaqueP256Keypair::Initialize(chip::Crypto::ECPKeyTarget key_target)
 {
     if (mPubkeyLength > 0)
     {
         // already have a key - ECDH use case where CASESession is calling Initialize()
         return CHIP_NO_ERROR;
     }

     ChipLogError(Crypto, "Initialize() is invalid on opaque keys, use Create() instead");
     return CHIP_ERROR_NOT_IMPLEMENTED;
 }

 CHIP_ERROR EFR32OpaqueP256Keypair::Serialize(P256SerializedKeypair & output) const
 {
     ChipLogError(Crypto, "Serialisation is invalid on opaque keys, share the object instead");
     return CHIP_ERROR_NOT_IMPLEMENTED;
 }

 CHIP_ERROR EFR32OpaqueP256Keypair::Deserialize(P256SerializedKeypair & input)
 {
     ChipLogError(Crypto, "Serialisation is invalid on opaque keys");
     return CHIP_ERROR_NOT_IMPLEMENTED;
 }

 CHIP_ERROR EFR32OpaqueP256Keypair::NewCertificateSigningRequest(uint8_t * out_csr, size_t & csr_length) const
 {
     MutableByteSpan csr(out_csr, csr_length);
     CHIP_ERROR err = GenerateCertificateSigningRequest(this, csr);
     csr_length     = (CHIP_NO_ERROR == err) ? csr.size() : 0;
     return err;
 }

 CHIP_ERROR EFR32OpaqueP256Keypair::ECDSA_sign_msg(const uint8_t * msg, size_t msg_length, P256ECDSASignature & out_signature) const
 {
     CHIP_ERROR error     = CHIP_NO_ERROR;
     size_t output_length = 0;

     VerifyOrExit((msg != nullptr) && (msg_length > 0), error = CHIP_ERROR_INVALID_ARGUMENT);

     error = Sign(msg, msg_length, out_signature.Bytes(), out_signature.Capacity(), &output_length);

     SuccessOrExit(error);
     SuccessOrExit(error = out_signature.SetLength(output_length));
 exit:
     return error;
 }

 CHIP_ERROR EFR32OpaqueP256Keypair::ECDH_derive_secret(const P256PublicKey & remote_public_key,
                                                       P256ECDHDerivedSecret & out_secret) const
 {
     CHIP_ERROR error     = CHIP_NO_ERROR;
     size_t output_length = 0;

     error = Derive(Uint8::to_const_uchar(remote_public_key), remote_public_key.Length(), out_secret.Bytes(),
                    (out_secret.Length() == 0) ? out_secret.Capacity() : out_secret.Length(), &output_length);

     SuccessOrExit(error);
     SuccessOrExit(error = out_secret.SetLength(output_length));
 exit:
     return error;
 }

 const P256PublicKey & EFR32OpaqueP256Keypair::Pubkey() const
 {
     return mPubKey;
 }

 } // namespace Internal
 } // namespace DeviceLayer
 } // namespace chip
	/*
	* Copyright (c) 2022 Project CHIP Authors
	* All rights reserved.
	*
	* 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.
	*/

	#include "Efr32OpaqueKeypair.h"
	#include "em_device.h"
	#include <psa/crypto.h>

	#include <lib/core/CHIPSafeCasts.h>
	#include <lib/support/CHIPMem.h>
	#include <lib/support/SafeInt.h>
	using chip::Platform::MemoryCalloc;
	using chip::Platform::MemoryFree;

	using chip::Crypto::P256ECDHDerivedSecret;
	using chip::Crypto::P256ECDSASignature;
	using chip::Crypto::P256Keypair;
	using chip::Crypto::P256PublicKey;
	using chip::Crypto::P256SerializedKeypair;

	namespace chip {
	namespace DeviceLayer {
	namespace Internal {

	/*******************************************************************************
	*
	* PSA key ID range for storing Matter Opaque keys
	*
	******************************************************************************/
	#define PSA_KEY_ID_FOR_MATTER_MIN (0x00004400)
	#define PSA_KEY_ID_FOR_MATTER_MAX (0x000045FF)
	#define PSA_KEY_ID_FOR_MATTER_SIZE (PSA_KEY_ID_FOR_MATTER_MAX - PSA_KEY_ID_FOR_MATTER_MIN + 1)

	static_assert((kEFR32OpaqueKeyIdPersistentMax - kEFR32OpaqueKeyIdPersistentMin) < PSA_KEY_ID_FOR_MATTER_SIZE,
	"Not enough PSA range to store all allowed opaque key IDs");

	#if defined(SEMAILBOX_PRESENT) && (_SILICON_LABS_SECURITY_FEATURE == _SILICON_LABS_SECURITY_FEATURE_VAULT)
	#define PSA_CRYPTO_LOCATION_FOR_DEVICE PSA_KEY_LOCATION_SL_SE_OPAQUE
	#elif defined(CRYPTOACC_PRESENT) && defined(SEPUF_PRESENT) && defined(SL_TRUSTZONE_NONSECURE)
	#define PSA_CRYPTO_LOCATION_FOR_DEVICE PSA_KEY_LOCATION_SL_CRYPTOACC_OPAQUE
	#else
	#define PSA_CRYPTO_LOCATION_FOR_DEVICE PSA_KEY_LOCATION_LOCAL_STORAGE
	#endif

	static void _log_PSA_error(psa_status_t status)
	{
	if (status != PSA_SUCCESS)
	{
	ChipLogError(Crypto, "PSA error: %ld", status);
	}
	}

	/*******************************************************************************
	*
	* PSA Crypto backed implementation of EFR32OpaqueKeypair
	*
	******************************************************************************/

	static bool is_opaque_key_valid(EFR32OpaqueKeyId id)
	{
	if (id == kEFR32OpaqueKeyIdVolatile)
	{
	return true;
	}
	else if (id >= kEFR32OpaqueKeyIdPersistentMin && id <= (kEFR32OpaqueKeyIdPersistentMin + PSA_KEY_ID_FOR_MATTER_SIZE))
	{
	return true;
	}

	return false;
	}

	static mbedtls_svc_key_id_t psa_key_id_from_opaque(EFR32OpaqueKeyId id)
	{
	if (id == kEFR32OpaqueKeyIdVolatile \|\| !is_opaque_key_valid(id))
	{
	return 0;
	}

	return PSA_KEY_ID_FOR_MATTER_MIN + (id - kEFR32OpaqueKeyIdPersistentMin);
	}

	static EFR32OpaqueKeyId opaque_key_id_from_psa(mbedtls_svc_key_id_t id)
	{
	if (id == 0)
	{
	return kEFR32OpaqueKeyIdVolatile;
	}
	else if (id >= PSA_KEY_ID_FOR_MATTER_MIN && id <= PSA_KEY_ID_FOR_MATTER_MAX)
	{
	return (id + kEFR32OpaqueKeyIdPersistentMin) - PSA_KEY_ID_FOR_MATTER_MIN;
	}
	else
	{
	return kEFR32OpaqueKeyIdUnknown;
	}
	}

	EFR32OpaqueKeypair::EFR32OpaqueKeypair()
	{
	psa_crypto_init();
	// Avoid having a reference to PSA datatypes in the signature of this class
	mContext = MemoryCalloc(1, sizeof(mbedtls_svc_key_id_t));
	}

	EFR32OpaqueKeypair::~EFR32OpaqueKeypair()
	{
	// Free key resources
	if (mContext != nullptr)
	{
	// Delete volatile keys, since nobody else can after we drop the key ID.
	if (!mIsPersistent)
	{
	DestroyKey();
	}

	MemoryFree(mContext);
	mContext = nullptr;
	}
	}

	CHIP_ERROR EFR32OpaqueKeypair::Load(EFR32OpaqueKeyId opaque_id)
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	psa_status_t status = PSA_ERROR_BAD_STATE;
	mbedtls_svc_key_id_t key_id = 0;

	VerifyOrExit(opaque_id != kEFR32OpaqueKeyIdVolatile, error = CHIP_ERROR_INVALID_ARGUMENT);
	VerifyOrExit(is_opaque_key_valid(opaque_id), error = CHIP_ERROR_INVALID_ARGUMENT);
	VerifyOrExit(mContext, error = CHIP_ERROR_INCORRECT_STATE);

	// If the object contains a volatile key, clean it up before reusing the object storage
	if (mHasKey && !mIsPersistent)
	{
	DestroyKey();
	}

	key_id = psa_key_id_from_opaque(opaque_id);

	status = psa_export_public_key(key_id, mPubkeyRef, mPubkeySize, &mPubkeyLength);

	if (status == PSA_ERROR_DOES_NOT_EXIST)
	{
	error = CHIP_DEVICE_ERROR_CONFIG_NOT_FOUND;
	goto exit;
	}

	VerifyOrExit(status == PSA_SUCCESS, {
	_log_PSA_error(status);
	error = CHIP_ERROR_INTERNAL;
	});

	// Store the key ID and mark the key as valid
	(mbedtls_svc_key_id_t ) mContext = key_id;
	mHasKey = true;
	mIsPersistent = true;

	exit:
	if (error != CHIP_NO_ERROR)
	{
	memset(mPubkeyRef, 0, mPubkeySize);
	}

	return error;
	}

	CHIP_ERROR EFR32OpaqueKeypair::Create(EFR32OpaqueKeyId opaque_id, EFR32OpaqueKeyUsages usage)
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	psa_status_t status = PSA_ERROR_BAD_STATE;
	psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT;
	mbedtls_svc_key_id_t key_id = 0;

	VerifyOrExit(is_opaque_key_valid(opaque_id), error = CHIP_ERROR_INVALID_ARGUMENT);
	VerifyOrExit(mContext, error = CHIP_ERROR_INCORRECT_STATE);

	if (opaque_id == kEFR32OpaqueKeyIdVolatile)
	{
	psa_set_key_lifetime(
	&attr, PSA_KEY_LIFETIME_FROM_PERSISTENCE_AND_LOCATION(PSA_KEY_LIFETIME_VOLATILE, PSA_CRYPTO_LOCATION_FOR_DEVICE));
	}
	else
	{
	psa_key_handle_t key_handle;

	key_id = psa_key_id_from_opaque(opaque_id);

	// Check if the key already exists
	int ret = psa_open_key(key_id, &key_handle);
	if (PSA_SUCCESS == ret)
	{
	// WARNING: Existing key! This is caused by a problem in the key store.
	// The key must be destroyed, otherwhise the device won't recover.
	ChipLogError(Crypto, "WARNING: PSA key recycled: %d / %ld", opaque_id, key_id);
	psa_destroy_key(key_id);
	}

	psa_set_key_id(&attr, key_id);
	psa_set_key_lifetime(
	&attr, PSA_KEY_LIFETIME_FROM_PERSISTENCE_AND_LOCATION(PSA_KEY_LIFETIME_PERSISTENT, PSA_CRYPTO_LOCATION_FOR_DEVICE));
	}

	switch (usage)
	{
	case EFR32OpaqueKeyUsages::ECDSA_P256_SHA256:
	psa_set_key_type(&attr, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_bits(&attr, 256);
	psa_set_key_algorithm(&attr, PSA_ALG_ECDSA(PSA_ALG_SHA_256));
	// Need hash signing permissions because the CSR generation uses sign_hash internally
	psa_set_key_usage_flags(&attr, PSA_KEY_USAGE_SIGN_MESSAGE \| PSA_KEY_USAGE_SIGN_HASH);
	break;
	case EFR32OpaqueKeyUsages::ECDH_P256:
	psa_set_key_type(&attr, PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_FAMILY_SECP_R1));
	psa_set_key_bits(&attr, 256);
	psa_set_key_algorithm(&attr, PSA_ALG_ECDH);
	psa_set_key_usage_flags(&attr, PSA_KEY_USAGE_DERIVE);
	break;
	}

	status = psa_generate_key(&attr, &key_id);
	VerifyOrExit(status == PSA_SUCCESS, {
	_log_PSA_error(status);
	error = CHIP_ERROR_INTERNAL;
	});

	// Export the public key
	status = psa_export_public_key(key_id, mPubkeyRef, mPubkeySize, &mPubkeyLength);
	if (PSA_SUCCESS != status)
	{
	_log_PSA_error(status);
	// Key generation succeeded, but pubkey export did not. To avoid
	// memory leaks, delete the generated key before returning the error
	psa_destroy_key(key_id);
	error = CHIP_ERROR_INTERNAL;
	goto exit;
	}

	// Store the key ID and mark the key as valid
	mHasKey = true;
	mIsPersistent = opaque_id != kEFR32OpaqueKeyIdVolatile;

	exit:
	psa_reset_key_attributes(&attr);
	if (mContext)
	{
	if (CHIP_NO_ERROR == error)
	{
	(mbedtls_svc_key_id_t ) mContext = key_id;
	}
	else
	{
	(mbedtls_svc_key_id_t ) mContext = 0;
	}
	}
	return error;
	}

	CHIP_ERROR EFR32OpaqueKeypair::GetPublicKey(uint8_t * output, size_t output_size, size_t * output_length) const
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

	if (output_size >= mPubkeyLength)
	{
	memcpy(output, mPubkeyRef, mPubkeyLength);
	*output_length = mPubkeyLength;
	}
	else
	{
	error = CHIP_ERROR_BUFFER_TOO_SMALL;
	}
	exit:
	return error;
	}

	EFR32OpaqueKeyId EFR32OpaqueKeypair::GetKeyId() const
	{
	if (!mHasKey)
	{
	return kEFR32OpaqueKeyIdUnknown;
	}

	if (!mIsPersistent)
	{
	return kEFR32OpaqueKeyIdVolatile;
	}

	return opaque_key_id_from_psa((mbedtls_svc_key_id_t ) mContext);
	}

	CHIP_ERROR EFR32OpaqueKeypair::Sign(const uint8_t * msg, size_t msg_len, uint8_t * output, size_t output_size,
	size_t * output_length) const
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	psa_status_t status = PSA_ERROR_BAD_STATE;

	VerifyOrExit(mContext, error = CHIP_ERROR_INCORRECT_STATE);
	VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

	status = psa_sign_message((mbedtls_svc_key_id_t ) mContext, PSA_ALG_ECDSA(PSA_ALG_SHA_256), msg, msg_len, output, output_size,
	output_length);

	VerifyOrExit(status == PSA_SUCCESS, {
	_log_PSA_error(status);
	error = CHIP_ERROR_INTERNAL;
	});

	exit:
	return error;
	}

	CHIP_ERROR EFR32OpaqueKeypair::Derive(const uint8_t * their_key, size_t their_key_len, uint8_t * output, size_t output_size,
	size_t * output_length) const
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	psa_status_t status = PSA_ERROR_BAD_STATE;

	VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

	status = psa_raw_key_agreement(PSA_ALG_ECDH, (mbedtls_svc_key_id_t ) mContext, their_key, their_key_len, output, output_size,
	output_length);

	VerifyOrExit(status == PSA_SUCCESS, {
	_log_PSA_error(status);
	error = CHIP_ERROR_INTERNAL;
	});

	exit:
	return error;
	}

	CHIP_ERROR EFR32OpaqueKeypair::DestroyKey()
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	psa_status_t status = PSA_ERROR_BAD_STATE;

	VerifyOrExit(mHasKey, error = CHIP_ERROR_INCORRECT_STATE);

	status = psa_destroy_key((mbedtls_svc_key_id_t ) mContext);
	VerifyOrExit(status == PSA_SUCCESS, {
	_log_PSA_error(status);
	error = CHIP_ERROR_INTERNAL;
	});

	exit:
	mHasKey = false;
	mIsPersistent = false;
	memset(mPubkeyRef, 0, mPubkeySize);
	if (mContext)
	{
	(mbedtls_svc_key_id_t ) mContext = 0;
	}
	return error;
	}

	/*******************************************************************************
	*
	* PSA Crypto backed implementation of EFR32OpaqueP256Keypair
	*
	******************************************************************************/
	EFR32OpaqueP256Keypair::EFR32OpaqueP256Keypair()
	{
	mPubkeyRef = mPubKey.Bytes();
	mPubkeySize = mPubKey.Length();
	mPubkeyLength = 0;
	}

	EFR32OpaqueP256Keypair::~EFR32OpaqueP256Keypair() {}

	CHIP_ERROR EFR32OpaqueP256Keypair::Initialize(chip::Crypto::ECPKeyTarget key_target)
	{
	if (mPubkeyLength > 0)
	{
	// already have a key - ECDH use case where CASESession is calling Initialize()
	return CHIP_NO_ERROR;
	}

	ChipLogError(Crypto, "Initialize() is invalid on opaque keys, use Create() instead");
	return CHIP_ERROR_NOT_IMPLEMENTED;
	}

	CHIP_ERROR EFR32OpaqueP256Keypair::Serialize(P256SerializedKeypair & output) const
	{
	ChipLogError(Crypto, "Serialisation is invalid on opaque keys, share the object instead");
	return CHIP_ERROR_NOT_IMPLEMENTED;
	}

	CHIP_ERROR EFR32OpaqueP256Keypair::Deserialize(P256SerializedKeypair & input)
	{
	ChipLogError(Crypto, "Serialisation is invalid on opaque keys");
	return CHIP_ERROR_NOT_IMPLEMENTED;
	}

	CHIP_ERROR EFR32OpaqueP256Keypair::NewCertificateSigningRequest(uint8_t * out_csr, size_t & csr_length) const
	{
	MutableByteSpan csr(out_csr, csr_length);
	CHIP_ERROR err = GenerateCertificateSigningRequest(this, csr);
	csr_length = (CHIP_NO_ERROR == err) ? csr.size() : 0;
	return err;
	}

	CHIP_ERROR EFR32OpaqueP256Keypair::ECDSA_sign_msg(const uint8_t * msg, size_t msg_length, P256ECDSASignature & out_signature) const
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	size_t output_length = 0;

	VerifyOrExit((msg != nullptr) && (msg_length > 0), error = CHIP_ERROR_INVALID_ARGUMENT);

	error = Sign(msg, msg_length, out_signature.Bytes(), out_signature.Capacity(), &output_length);

	SuccessOrExit(error);
	SuccessOrExit(error = out_signature.SetLength(output_length));
	exit:
	return error;
	}

	CHIP_ERROR EFR32OpaqueP256Keypair::ECDH_derive_secret(const P256PublicKey & remote_public_key,
	P256ECDHDerivedSecret & out_secret) const
	{
	CHIP_ERROR error = CHIP_NO_ERROR;
	size_t output_length = 0;

	error = Derive(Uint8::to_const_uchar(remote_public_key), remote_public_key.Length(), out_secret.Bytes(),
	(out_secret.Length() == 0) ? out_secret.Capacity() : out_secret.Length(), &output_length);

	SuccessOrExit(error);
	SuccessOrExit(error = out_secret.SetLength(output_length));
	exit:
	return error;
	}

	const P256PublicKey & EFR32OpaqueP256Keypair::Pubkey() const
	{
	return mPubKey;
	}

	} // namespace Internal
	} // namespace DeviceLayer
	} // namespace chip