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/*
* Copyright (C) 2022 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.
*/
package com.android.adservices.service.measurement.aggregation;
import android.net.Uri;
import com.android.adservices.LogUtil;
import com.android.adservices.data.measurement.DatastoreManager;
import com.android.adservices.service.AdServicesConfig;
import com.android.internal.annotations.VisibleForTesting;
import java.time.Clock;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.Random;
/** A public key used to encrypt aggregatable reports. */
public final class AggregateEncryptionKeyManager {
private final DatastoreManager mDatastoreManager;
private final AggregateEncryptionKeyFetcher mAggregateEncryptionKeyFetcher;
private final Clock mClock;
private final Uri mAggregateEncryptionKeyCoordinatorUrl;
public AggregateEncryptionKeyManager(DatastoreManager datastoreManager) {
mDatastoreManager = datastoreManager;
mAggregateEncryptionKeyFetcher = new AggregateEncryptionKeyFetcher();
mClock = Clock.systemUTC();
mAggregateEncryptionKeyCoordinatorUrl =
Uri.parse(AdServicesConfig.getMeasurementAggregateEncryptionKeyCoordinatorUrl());
}
@VisibleForTesting
AggregateEncryptionKeyManager(DatastoreManager datastoreManager,
AggregateEncryptionKeyFetcher aggregateEncryptionKeyFetcher,
Clock clock,
Uri aggregateEncryptionKeyCoordinatorUrl) {
mDatastoreManager = datastoreManager;
mAggregateEncryptionKeyFetcher = aggregateEncryptionKeyFetcher;
mClock = clock;
mAggregateEncryptionKeyCoordinatorUrl = aggregateEncryptionKeyCoordinatorUrl;
}
/**
* Retrieves a {@link List<AggregateEncryptionKey>} in which the size of the collection matches
* the numKeys specified in the parameters. If no keys are found, the collection would be empty.
*/
public List<AggregateEncryptionKey> getAggregateEncryptionKeys(int numKeys) {
long eventTime = mClock.millis();
Optional<List<AggregateEncryptionKey>> aggregateEncryptionKeysOptional =
mDatastoreManager.runInTransactionWithResult((dao) ->
dao.getNonExpiredAggregateEncryptionKeys(eventTime));
List<AggregateEncryptionKey> aggregateEncryptionKeys =
aggregateEncryptionKeysOptional.orElse(new ArrayList<>());
// If no non-expired keys are available (or the datastore retrieval failed), fetch them
// over the network, insert them in the datastore and delete expired keys.
if (aggregateEncryptionKeys.size() == 0) {
Optional<List<AggregateEncryptionKey>> fetchResult =
mAggregateEncryptionKeyFetcher.fetch(
mAggregateEncryptionKeyCoordinatorUrl, eventTime);
if (fetchResult.isPresent()) {
aggregateEncryptionKeys = fetchResult.get();
for (AggregateEncryptionKey aggregateEncryptionKey : aggregateEncryptionKeys) {
mDatastoreManager.runInTransaction((dao) ->
dao.insertAggregateEncryptionKey(aggregateEncryptionKey));
}
mDatastoreManager.runInTransaction((dao) ->
dao.deleteExpiredAggregateEncryptionKeys(eventTime));
} else {
LogUtil.d("Fetching aggregate encryption keys over the network failed.");
}
}
return getRandomListOfKeys(aggregateEncryptionKeys, numKeys);
}
@VisibleForTesting
List<AggregateEncryptionKey> getRandomListOfKeys(
List<AggregateEncryptionKey> aggregateEncryptionKeys, int numKeys) {
List<AggregateEncryptionKey> result = new ArrayList<>();
Random random = new Random();
int numAvailableKeys = aggregateEncryptionKeys.size();
if (numAvailableKeys > 0) {
for (int i = 0; i < numKeys; i++) {
int index = random.nextInt(numAvailableKeys);
result.add(aggregateEncryptionKeys.get(index));
}
}
return result;
}
}
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