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/*
* Copyright 2014 The Android Open Source Project
*
* 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 <keymaster/km_openssl/aes_key.h>
#include <assert.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "aes_operation.h"
namespace keymaster {
static AesOperationFactory encrypt_factory(KM_PURPOSE_ENCRYPT);
static AesOperationFactory decrypt_factory(KM_PURPOSE_DECRYPT);
OperationFactory* AesKeyFactory::GetOperationFactory(keymaster_purpose_t purpose) const {
switch (purpose) {
case KM_PURPOSE_ENCRYPT:
return &encrypt_factory;
case KM_PURPOSE_DECRYPT:
return &decrypt_factory;
default:
return nullptr;
}
}
keymaster_error_t AesKeyFactory::LoadKey(KeymasterKeyBlob&& key_material,
const AuthorizationSet& /* additional_params */,
AuthorizationSet&& hw_enforced,
AuthorizationSet&& sw_enforced,
UniquePtr<Key>* key) const {
if (!key) return KM_ERROR_OUTPUT_PARAMETER_NULL;
uint32_t min_mac_length = 0;
if (hw_enforced.Contains(TAG_BLOCK_MODE, KM_MODE_GCM) ||
sw_enforced.Contains(TAG_BLOCK_MODE, KM_MODE_GCM)) {
if (!hw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length) &&
!sw_enforced.GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length)) {
LOG_E("AES-GCM key must have KM_TAG_MIN_MAC_LENGTH", 0);
return KM_ERROR_INVALID_KEY_BLOB;
}
}
keymaster_error_t error = KM_ERROR_OK;
key->reset(new (std::nothrow)
AesKey(move(key_material), move(hw_enforced), move(sw_enforced), this));
if (!key->get()) error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
return error;
}
keymaster_error_t AesKeyFactory::validate_algorithm_specific_new_key_params(
const AuthorizationSet& key_description) const {
if (key_description.Contains(TAG_BLOCK_MODE, KM_MODE_GCM)) {
uint32_t min_tag_length;
if (!key_description.GetTagValue(TAG_MIN_MAC_LENGTH, &min_tag_length))
return KM_ERROR_MISSING_MIN_MAC_LENGTH;
if (min_tag_length % 8 != 0) return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
if (min_tag_length < kMinGcmTagLength || min_tag_length > kMaxGcmTagLength)
return KM_ERROR_UNSUPPORTED_MIN_MAC_LENGTH;
} else {
// Not GCM
if (key_description.find(TAG_MIN_MAC_LENGTH) != -1) {
LOG_W("KM_TAG_MIN_MAC_LENGTH found for non AES-GCM key", 0);
return KM_ERROR_INVALID_TAG;
}
}
return KM_ERROR_OK;
}
} // namespace keymaster