src/adaptations/device-layer/EFR32/GroupKeyStoreImpl.cpp - third_party/openweave-core - Git at Google

 /*
  *
  *    Copyright (c) 2019 Nest Labs, Inc.
  *    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.
  */

 /**
  *    @file
  *          Provides an implementation of the Weave GroupKeyStore interface
  *          for platforms based on the Silicon Labs SDK.
  */

 #include <Weave/DeviceLayer/internal/WeaveDeviceLayerInternal.h>
 #include <Weave/DeviceLayer/EFR32/GroupKeyStoreImpl.h>

 using namespace ::nl;
 using namespace ::nl::Weave;
 using namespace ::nl::Weave::Profiles::Security::AppKeys;

 namespace nl {
 namespace Weave {
 namespace DeviceLayer {
 namespace Internal {

 WEAVE_ERROR GroupKeyStoreImpl::RetrieveGroupKey(uint32_t keyId, WeaveGroupKey &key)
 {
     WEAVE_ERROR err;

     // Iterate over all the GroupKey nvm3 records looking for a matching key...
     err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
                         [keyId, &key](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
                             WEAVE_ERROR err2;
                             size_t      keyLen;
                             uint8_t     buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
                             uint32_t    curKeyId;

                             // Read the nvm3 obj binary data data into the buffer.
                             err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);

                             // Decode the Weave key id for the current key.
                             err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
                             SuccessOrExit(err2);

                             // If it matches the key we're looking for...
                             if (curKeyId == keyId)
                             {
                                 // Decode the associated key data.
                                 err2 = DecodeGroupKey(buf, keyLen, key);
                                 SuccessOrExit(err2);

                                 // End the iteration by returning a WEAVE_END_OF_INPUT result.
                                 ExitNow(err2 = WEAVE_END_OF_INPUT);
                             }

                         exit:
                             return err2;
                         });

     // Modify error code for return.
     switch (err)
     {
     case WEAVE_END_OF_INPUT:
         err = WEAVE_NO_ERROR; // Match found.
         break;
     case WEAVE_NO_ERROR:
         err = WEAVE_ERROR_KEY_NOT_FOUND; // Match not found.
         break;
     default:
         break;
     }

     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::StoreGroupKey(const WeaveGroupKey &key)
 {
     WEAVE_ERROR err;

     // Delete any existing group key with the same id (this may or may not exit).
     DeleteGroupKey(key.KeyId); // no error checking here.

     // Iterate over all the GroupKey nvm3 records looking for the first
     // empty nvm3 key where we can store the data. (Note- use arg addNewrecord=true)
     err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, true,
                         [&key](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
                             WEAVE_ERROR err2;
                             size_t      keyLen;
                             uint8_t     buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)

                             // Encode the key for storage in an nvm3 record.
                             err2 = EncodeGroupKey(key, buf, sizeof(buf), keyLen);
                             SuccessOrExit(err2);

                             // Write the encoded binary data into the nvm3 object.
                             err2 = WriteConfigValueBin(nvm3Key, buf, keyLen);
                             SuccessOrExit(err2);

                             // End the iteration by returning a WEAVE_END_OF_INPUT result.
                             ExitNow(err2 = WEAVE_END_OF_INPUT);

                         exit:
                             return err2;
                         });

     // Modify error code for return.
     switch (err)
     {
     case WEAVE_END_OF_INPUT:
         err = WEAVE_NO_ERROR; // Key entry was stored.
         break;
     case WEAVE_NO_ERROR:
         err = WEAVE_ERROR_KEY_NOT_FOUND; // Key entry was not stored.
         break;
     default:
         break;
     }

     if (err == WEAVE_NO_ERROR)
     {
 #if WEAVE_PROGRESS_LOGGING
         {
             char extraKeyInfo[32];
             if (WeaveKeyId::IsAppEpochKey(key.KeyId))
             {
                 snprintf(extraKeyInfo, sizeof(extraKeyInfo), ", start time %" PRId32, key.StartTime);
             }
             else if (WeaveKeyId::IsAppGroupMasterKey(key.KeyId))
             {
                 snprintf(extraKeyInfo, sizeof(extraKeyInfo), ", global id 0x%08" PRIX32, key.GlobalId);
             }
             else
             {
                 extraKeyInfo[0] = 0;
             }

 #if WEAVE_CONFIG_SECURITY_TEST_MODE
             WeaveLogProgress(SecurityManager,
                              "GroupKeyStore: storing key 0x%08" PRIX32 " (%s), len %" PRId8 ", data 0x%02" PRIX8
                              "...%s",
                              key.KeyId, WeaveKeyId::DescribeKey(key.KeyId), key.KeyLen, key.Key[0], extraKeyInfo);
 #else
             WeaveLogProgress(SecurityManager, "GroupKeyStore: storing key 0x%08" PRIX32 " (%s), len %" PRId8 "%s",
                              key.KeyId, WeaveKeyId::DescribeKey(key.KeyId), key.KeyLen, extraKeyInfo);
 #endif
         }

 #endif // WEAVE_PROGRESS_LOGGING
     }

     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::DeleteGroupKey(uint32_t keyId)
 {
     WEAVE_ERROR err;

     // Iterate over all the GroupKey nvm3 records looking for a matching key...
     err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
                         [keyId](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
                             WEAVE_ERROR err2;
                             size_t      keyLen;
                             uint8_t     buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
                             uint32_t    curKeyId;

                             // Read the nvm3 obj binary data data into the buffer.
                             err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);
                             SuccessOrExit(err2);

                             // Decode the Weave key id for the current group key.
                             err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
                             SuccessOrExit(err2);

                             // If it matches the key we are looking for, delete the nvm3 record.
                             if (curKeyId == keyId)
                             {
                                 err2 = ClearConfigValue(nvm3Key);
                                 WeaveLogProgress(DeviceLayer, "GroupKeyStore: deleting key 0x%08" PRIX32, curKeyId);

                                 // End the iteration by returning a WEAVE_END_OF_INPUT result.
                                 ExitNow(err2 = WEAVE_END_OF_INPUT);
                             }

                         exit:
                             return err2;
                         });

     // Modify error code for return.
     switch (err)
     {
     case WEAVE_END_OF_INPUT:
         err = WEAVE_NO_ERROR; // Key entry was deleted.
         break;
     case WEAVE_NO_ERROR:
         err = WEAVE_ERROR_KEY_NOT_FOUND; // Key entry was not deleted.
         break;
     default:
         break;
     }

     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::DeleteGroupKeysOfAType(uint32_t keyType)
 {
     WEAVE_ERROR err;

     // Iterate over all the GroupKey nvm3 records looking for a matching key...
     err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
                         [keyType](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
                             WEAVE_ERROR err2;
                             size_t      keyLen;
                             uint8_t     buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
                             uint32_t    curKeyId;

                             // Read the nvm3 obj binary data data into the buffer.
                             err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);
                             SuccessOrExit(err2);

                             // Decode the Weave key id for the current group key.
                             err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
                             SuccessOrExit(err2);

                             // If the current key matches the type we are looking for, delete the nvm3 record.
                             if (WeaveKeyId::GetType(curKeyId) == keyType)
                             {
                                 err2 = ClearConfigValue(nvm3Key);
                                 WeaveLogProgress(DeviceLayer, "GroupKeyStore: deleting key 0x%08" PRIX32, curKeyId);
                             }

                         exit:
                             return err2;
                         });

     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::EnumerateGroupKeys(uint32_t  keyType,
                                                   uint32_t *keyIds,
                                                   uint8_t   keyIdsArraySize,
                                                   uint8_t & keyCount)
 {
     WEAVE_ERROR err;

     keyCount = 0;

     // Iterate over all the GroupKey records looking for keys of the specified type...
     err = ForEachRecord(
         kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
         [keyType, keyIds, keyIdsArraySize, &keyCount](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
             WEAVE_ERROR err2;
             size_t      keyLen;
             uint8_t     buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
             uint32_t    curKeyId;

             // Read the nvm3 obj binary data data into the buffer.
             err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);
             SuccessOrExit(err2);

             // Decode the Weave key id for the current group key.
             err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
             SuccessOrExit(err2);

             // If the current key matches the type we're looking for, add it to the keyIds array.
             if ((keyType == WeaveKeyId::kType_None) || (WeaveKeyId::GetType(curKeyId) == keyType))
             {
                 keyIds[keyCount++] = curKeyId;

                 // Stop iterating if there's no more room in the keyIds array.
                 VerifyOrExit(keyCount < keyIdsArraySize, err2 = WEAVE_ERROR_BUFFER_TOO_SMALL);
             }

         exit:
             return err2;
         });

     // Simply return a truncated list if there are more matching keys than will fit in the array.
     if (err == WEAVE_ERROR_BUFFER_TOO_SMALL)
     {
         err = WEAVE_NO_ERROR;
     }

     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::Clear(void)
 {
     WEAVE_ERROR err;

     // Iterate over all the GroupKey nvm3 records deleting each one...
     err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
                         [](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
                             WEAVE_ERROR err2;

                             err2 = ClearConfigValue(nvm3Key);
                             SuccessOrExit(err2);

                         exit:
                             return err2;
                         });

     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::RetrieveLastUsedEpochKeyId(void)
 {
     WEAVE_ERROR err;

     err = ReadConfigValue(kConfigKey_LastUsedEpochKeyId, LastUsedEpochKeyId);
     if (err == WEAVE_DEVICE_ERROR_CONFIG_NOT_FOUND)
     {
         LastUsedEpochKeyId = WeaveKeyId::kNone;
         err                = WEAVE_NO_ERROR;
     }
     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::StoreLastUsedEpochKeyId(void)
 {
     return WriteConfigValue(kConfigKey_LastUsedEpochKeyId, LastUsedEpochKeyId);
 }

 WEAVE_ERROR GroupKeyStoreImpl::Init()
 {
     // Nothing to do
     return WEAVE_NO_ERROR;
 }

 WEAVE_ERROR GroupKeyStoreImpl::EncodeGroupKey(const WeaveGroupKey &key,
                                               uint8_t *            buf,
                                               size_t               bufSize,
                                               size_t &             encodedKeyLen)
 {
     WEAVE_ERROR err = WEAVE_NO_ERROR;
     uint8_t *   p   = buf;

     VerifyOrExit(bufSize >= kFixedEncodedKeySize + key.KeyLen, err = WEAVE_ERROR_BUFFER_TOO_SMALL);

     Encoding::LittleEndian::Write32(p, key.KeyId);
     Encoding::LittleEndian::Write32(p, key.StartTime);
     Encoding::Write8(p, key.KeyLen);
     memcpy(p, key.Key, key.KeyLen);
     p += key.KeyLen;

     encodedKeyLen = p - buf;

 exit:
     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::DecodeGroupKeyId(const uint8_t *encodedKey, size_t encodedKeyLen, uint32_t &keyId)
 {
     WEAVE_ERROR err = WEAVE_NO_ERROR;

     VerifyOrExit(encodedKeyLen >= kFixedEncodedKeySize, err = WEAVE_ERROR_INVALID_ARGUMENT);

     keyId = Encoding::LittleEndian::Get32(encodedKey);

 exit:
     return err;
 }

 WEAVE_ERROR GroupKeyStoreImpl::DecodeGroupKey(const uint8_t *encodedKey, size_t encodedKeyLen, WeaveGroupKey &key)
 {
     WEAVE_ERROR    err = WEAVE_NO_ERROR;
     const uint8_t *p   = encodedKey;

     VerifyOrExit(encodedKeyLen >= kFixedEncodedKeySize, err = WEAVE_ERROR_INVALID_ARGUMENT);

     key.KeyId     = Encoding::LittleEndian::Read32(p);
     key.StartTime = Encoding::LittleEndian::Read32(p);
     key.KeyLen    = Encoding::Read8(p);

     VerifyOrExit(encodedKeyLen >= kFixedEncodedKeySize + key.KeyLen, err = WEAVE_ERROR_INVALID_ARGUMENT);

     memcpy(key.Key, p, key.KeyLen);

 exit:
     return err;
 }

 } // namespace Internal
 } // namespace DeviceLayer
 } // namespace Weave
 } // namespace nl
	/*
	*
	* Copyright (c) 2019 Nest Labs, Inc.
	* 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.
	*/

	/**
	* @file
	* Provides an implementation of the Weave GroupKeyStore interface
	* for platforms based on the Silicon Labs SDK.
	*/

	#include <Weave/DeviceLayer/internal/WeaveDeviceLayerInternal.h>
	#include <Weave/DeviceLayer/EFR32/GroupKeyStoreImpl.h>

	using namespace ::nl;
	using namespace ::nl::Weave;
	using namespace ::nl::Weave::Profiles::Security::AppKeys;

	namespace nl {
	namespace Weave {
	namespace DeviceLayer {
	namespace Internal {

	WEAVE_ERROR GroupKeyStoreImpl::RetrieveGroupKey(uint32_t keyId, WeaveGroupKey &key)
	{
	WEAVE_ERROR err;

	// Iterate over all the GroupKey nvm3 records looking for a matching key...
	err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
	[keyId, &key](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
	WEAVE_ERROR err2;
	size_t keyLen;
	uint8_t buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
	uint32_t curKeyId;

	// Read the nvm3 obj binary data data into the buffer.
	err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);

	// Decode the Weave key id for the current key.
	err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
	SuccessOrExit(err2);

	// If it matches the key we're looking for...
	if (curKeyId == keyId)
	{
	// Decode the associated key data.
	err2 = DecodeGroupKey(buf, keyLen, key);
	SuccessOrExit(err2);

	// End the iteration by returning a WEAVE_END_OF_INPUT result.
	ExitNow(err2 = WEAVE_END_OF_INPUT);
	}

	exit:
	return err2;
	});

	// Modify error code for return.
	switch (err)
	{
	case WEAVE_END_OF_INPUT:
	err = WEAVE_NO_ERROR; // Match found.
	break;
	case WEAVE_NO_ERROR:
	err = WEAVE_ERROR_KEY_NOT_FOUND; // Match not found.
	break;
	default:
	break;
	}

	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::StoreGroupKey(const WeaveGroupKey &key)
	{
	WEAVE_ERROR err;

	// Delete any existing group key with the same id (this may or may not exit).
	DeleteGroupKey(key.KeyId); // no error checking here.

	// Iterate over all the GroupKey nvm3 records looking for the first
	// empty nvm3 key where we can store the data. (Note- use arg addNewrecord=true)
	err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, true,
	[&key](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
	WEAVE_ERROR err2;
	size_t keyLen;
	uint8_t buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)

	// Encode the key for storage in an nvm3 record.
	err2 = EncodeGroupKey(key, buf, sizeof(buf), keyLen);
	SuccessOrExit(err2);

	// Write the encoded binary data into the nvm3 object.
	err2 = WriteConfigValueBin(nvm3Key, buf, keyLen);
	SuccessOrExit(err2);

	// End the iteration by returning a WEAVE_END_OF_INPUT result.
	ExitNow(err2 = WEAVE_END_OF_INPUT);

	exit:
	return err2;
	});

	// Modify error code for return.
	switch (err)
	{
	case WEAVE_END_OF_INPUT:
	err = WEAVE_NO_ERROR; // Key entry was stored.
	break;
	case WEAVE_NO_ERROR:
	err = WEAVE_ERROR_KEY_NOT_FOUND; // Key entry was not stored.
	break;
	default:
	break;
	}

	if (err == WEAVE_NO_ERROR)
	{
	#if WEAVE_PROGRESS_LOGGING
	{
	char extraKeyInfo[32];
	if (WeaveKeyId::IsAppEpochKey(key.KeyId))
	{
	snprintf(extraKeyInfo, sizeof(extraKeyInfo), ", start time %" PRId32, key.StartTime);
	}
	else if (WeaveKeyId::IsAppGroupMasterKey(key.KeyId))
	{
	snprintf(extraKeyInfo, sizeof(extraKeyInfo), ", global id 0x%08" PRIX32, key.GlobalId);
	}
	else
	{
	extraKeyInfo[0] = 0;
	}

	#if WEAVE_CONFIG_SECURITY_TEST_MODE
	WeaveLogProgress(SecurityManager,
	"GroupKeyStore: storing key 0x%08" PRIX32 " (%s), len %" PRId8 ", data 0x%02" PRIX8
	"...%s",
	key.KeyId, WeaveKeyId::DescribeKey(key.KeyId), key.KeyLen, key.Key[0], extraKeyInfo);
	#else
	WeaveLogProgress(SecurityManager, "GroupKeyStore: storing key 0x%08" PRIX32 " (%s), len %" PRId8 "%s",
	key.KeyId, WeaveKeyId::DescribeKey(key.KeyId), key.KeyLen, extraKeyInfo);
	#endif
	}

	#endif // WEAVE_PROGRESS_LOGGING
	}

	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::DeleteGroupKey(uint32_t keyId)
	{
	WEAVE_ERROR err;

	// Iterate over all the GroupKey nvm3 records looking for a matching key...
	err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
	[keyId](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
	WEAVE_ERROR err2;
	size_t keyLen;
	uint8_t buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
	uint32_t curKeyId;

	// Read the nvm3 obj binary data data into the buffer.
	err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);
	SuccessOrExit(err2);

	// Decode the Weave key id for the current group key.
	err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
	SuccessOrExit(err2);

	// If it matches the key we are looking for, delete the nvm3 record.
	if (curKeyId == keyId)
	{
	err2 = ClearConfigValue(nvm3Key);
	WeaveLogProgress(DeviceLayer, "GroupKeyStore: deleting key 0x%08" PRIX32, curKeyId);

	// End the iteration by returning a WEAVE_END_OF_INPUT result.
	ExitNow(err2 = WEAVE_END_OF_INPUT);
	}

	exit:
	return err2;
	});

	// Modify error code for return.
	switch (err)
	{
	case WEAVE_END_OF_INPUT:
	err = WEAVE_NO_ERROR; // Key entry was deleted.
	break;
	case WEAVE_NO_ERROR:
	err = WEAVE_ERROR_KEY_NOT_FOUND; // Key entry was not deleted.
	break;
	default:
	break;
	}

	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::DeleteGroupKeysOfAType(uint32_t keyType)
	{
	WEAVE_ERROR err;

	// Iterate over all the GroupKey nvm3 records looking for a matching key...
	err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
	[keyType](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
	WEAVE_ERROR err2;
	size_t keyLen;
	uint8_t buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
	uint32_t curKeyId;

	// Read the nvm3 obj binary data data into the buffer.
	err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);
	SuccessOrExit(err2);

	// Decode the Weave key id for the current group key.
	err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
	SuccessOrExit(err2);

	// If the current key matches the type we are looking for, delete the nvm3 record.
	if (WeaveKeyId::GetType(curKeyId) == keyType)
	{
	err2 = ClearConfigValue(nvm3Key);
	WeaveLogProgress(DeviceLayer, "GroupKeyStore: deleting key 0x%08" PRIX32, curKeyId);
	}

	exit:
	return err2;
	});

	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::EnumerateGroupKeys(uint32_t keyType,
	uint32_t *keyIds,
	uint8_t keyIdsArraySize,
	uint8_t & keyCount)
	{
	WEAVE_ERROR err;

	keyCount = 0;

	// Iterate over all the GroupKey records looking for keys of the specified type...
	err = ForEachRecord(
	kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
	[keyType, keyIds, keyIdsArraySize, &keyCount](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
	WEAVE_ERROR err2;
	size_t keyLen;
	uint8_t buf[kMaxEncodedKeySize]; // (buf length == 45 bytes)
	uint32_t curKeyId;

	// Read the nvm3 obj binary data data into the buffer.
	err2 = ReadConfigValueBin(nvm3Key, buf, sizeof(buf), keyLen);
	SuccessOrExit(err2);

	// Decode the Weave key id for the current group key.
	err2 = DecodeGroupKeyId(buf, keyLen, curKeyId);
	SuccessOrExit(err2);

	// If the current key matches the type we're looking for, add it to the keyIds array.
	if ((keyType == WeaveKeyId::kType_None) \|\| (WeaveKeyId::GetType(curKeyId) == keyType))
	{
	keyIds[keyCount++] = curKeyId;

	// Stop iterating if there's no more room in the keyIds array.
	VerifyOrExit(keyCount < keyIdsArraySize, err2 = WEAVE_ERROR_BUFFER_TOO_SMALL);
	}

	exit:
	return err2;
	});

	// Simply return a truncated list if there are more matching keys than will fit in the array.
	if (err == WEAVE_ERROR_BUFFER_TOO_SMALL)
	{
	err = WEAVE_NO_ERROR;
	}

	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::Clear(void)
	{
	WEAVE_ERROR err;

	// Iterate over all the GroupKey nvm3 records deleting each one...
	err = ForEachRecord(kConfigKey_GroupKeyBase, kConfigKey_GroupKeyMax, false,
	[](const Key &nvm3Key, const size_t &length) -> WEAVE_ERROR {
	WEAVE_ERROR err2;

	err2 = ClearConfigValue(nvm3Key);
	SuccessOrExit(err2);

	exit:
	return err2;
	});

	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::RetrieveLastUsedEpochKeyId(void)
	{
	WEAVE_ERROR err;

	err = ReadConfigValue(kConfigKey_LastUsedEpochKeyId, LastUsedEpochKeyId);
	if (err == WEAVE_DEVICE_ERROR_CONFIG_NOT_FOUND)
	{
	LastUsedEpochKeyId = WeaveKeyId::kNone;
	err = WEAVE_NO_ERROR;
	}
	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::StoreLastUsedEpochKeyId(void)
	{
	return WriteConfigValue(kConfigKey_LastUsedEpochKeyId, LastUsedEpochKeyId);
	}

	WEAVE_ERROR GroupKeyStoreImpl::Init()
	{
	// Nothing to do
	return WEAVE_NO_ERROR;
	}

	WEAVE_ERROR GroupKeyStoreImpl::EncodeGroupKey(const WeaveGroupKey &key,
	uint8_t * buf,
	size_t bufSize,
	size_t & encodedKeyLen)
	{
	WEAVE_ERROR err = WEAVE_NO_ERROR;
	uint8_t * p = buf;

	VerifyOrExit(bufSize >= kFixedEncodedKeySize + key.KeyLen, err = WEAVE_ERROR_BUFFER_TOO_SMALL);

	Encoding::LittleEndian::Write32(p, key.KeyId);
	Encoding::LittleEndian::Write32(p, key.StartTime);
	Encoding::Write8(p, key.KeyLen);
	memcpy(p, key.Key, key.KeyLen);
	p += key.KeyLen;

	encodedKeyLen = p - buf;

	exit:
	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::DecodeGroupKeyId(const uint8_t *encodedKey, size_t encodedKeyLen, uint32_t &keyId)
	{
	WEAVE_ERROR err = WEAVE_NO_ERROR;

	VerifyOrExit(encodedKeyLen >= kFixedEncodedKeySize, err = WEAVE_ERROR_INVALID_ARGUMENT);

	keyId = Encoding::LittleEndian::Get32(encodedKey);

	exit:
	return err;
	}

	WEAVE_ERROR GroupKeyStoreImpl::DecodeGroupKey(const uint8_t *encodedKey, size_t encodedKeyLen, WeaveGroupKey &key)
	{
	WEAVE_ERROR err = WEAVE_NO_ERROR;
	const uint8_t *p = encodedKey;

	VerifyOrExit(encodedKeyLen >= kFixedEncodedKeySize, err = WEAVE_ERROR_INVALID_ARGUMENT);

	key.KeyId = Encoding::LittleEndian::Read32(p);
	key.StartTime = Encoding::LittleEndian::Read32(p);
	key.KeyLen = Encoding::Read8(p);

	VerifyOrExit(encodedKeyLen >= kFixedEncodedKeySize + key.KeyLen, err = WEAVE_ERROR_INVALID_ARGUMENT);

	memcpy(key.Key, p, key.KeyLen);

	exit:
	return err;
	}

	} // namespace Internal
	} // namespace DeviceLayer
	} // namespace Weave
	} // namespace nl