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// Copyright 2017 Google LLC
//
// 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.google.crypto.tink.daead;
import com.google.crypto.tink.DeterministicAead;
import com.google.crypto.tink.Key;
import com.google.crypto.tink.daead.internal.LegacyFullDeterministicAead;
import com.google.crypto.tink.internal.KeysetHandleInterface;
import com.google.crypto.tink.internal.LegacyProtoKey;
import com.google.crypto.tink.internal.MonitoringClient;
import com.google.crypto.tink.internal.MonitoringUtil;
import com.google.crypto.tink.internal.MutableMonitoringRegistry;
import com.google.crypto.tink.internal.MutablePrimitiveRegistry;
import com.google.crypto.tink.internal.PrefixMap;
import com.google.crypto.tink.internal.PrimitiveConstructor;
import com.google.crypto.tink.internal.PrimitiveRegistry;
import com.google.crypto.tink.internal.PrimitiveSet;
import com.google.crypto.tink.internal.PrimitiveWrapper;
import com.google.crypto.tink.util.Bytes;
import java.security.GeneralSecurityException;
/**
* The implementation of {@code PrimitiveWrapper}.
*
* The created primitive works with a keyset (rather than a single key). To encrypt a plaintext,
* it uses the primary key in the keyset, and prepends to the ciphertext a certain prefix associated
* with the primary key. To decrypt, the primitive uses the prefix of the ciphertext to efficiently
* select the right key in the set. If the keys associated with the prefix do not work, the
* primitive tries all keys with {@link com.google.crypto.tink.proto.OutputPrefixType#RAW}.
*/
public class DeterministicAeadWrapper
implements PrimitiveWrapper {
private static class DeterministicAeadWithId {
public DeterministicAeadWithId(DeterministicAead daead, int id) {
this.daead = daead;
this.id = id;
}
public final DeterministicAead daead;
public final int id;
}
private static final DeterministicAeadWrapper WRAPPER = new DeterministicAeadWrapper();
private static final PrimitiveConstructor
LEGACY_FULL_DAEAD_PRIMITIVE_CONSTRUCTOR =
PrimitiveConstructor.create(
LegacyFullDeterministicAead::create, LegacyProtoKey.class, DeterministicAead.class);
private static Bytes getOutputPrefix(Key key) throws GeneralSecurityException {
if (key instanceof DeterministicAeadKey) {
return ((DeterministicAeadKey) key).getOutputPrefix();
}
if (key instanceof LegacyProtoKey) {
return ((LegacyProtoKey) key).getOutputPrefix();
}
throw new GeneralSecurityException(
"Cannot get output prefix for key of class "
+ key.getClass().getName()
+ " with parameters "
+ key.getParameters());
}
private static class WrappedDeterministicAead implements DeterministicAead {
private final DeterministicAeadWithId primary;
private final PrefixMap allDaeads;
private final MonitoringClient.Logger encLogger;
private final MonitoringClient.Logger decLogger;
public WrappedDeterministicAead(
DeterministicAeadWithId primary,
PrefixMap allDaeads,
MonitoringClient.Logger encLogger,
MonitoringClient.Logger decLogger) {
this.primary = primary;
this.allDaeads = allDaeads;
this.encLogger = encLogger;
this.decLogger = decLogger;
}
@Override
public byte[] encryptDeterministically(final byte[] plaintext, final byte[] associatedData)
throws GeneralSecurityException {
try {
byte[] result = primary.daead.encryptDeterministically(plaintext, associatedData);
encLogger.log(primary.id, plaintext.length);
return result;
} catch (GeneralSecurityException e) {
encLogger.logFailure();
throw e;
}
}
@Override
public byte[] decryptDeterministically(final byte[] ciphertext, final byte[] associatedData)
throws GeneralSecurityException {
for (DeterministicAeadWithId aeadWithId : allDaeads.getAllWithMatchingPrefix(ciphertext)) {
try {
byte[] result = aeadWithId.daead.decryptDeterministically(ciphertext, associatedData);
decLogger.log(aeadWithId.id, ciphertext.length);
return result;
} catch (GeneralSecurityException ignored) {
// ignore and continue trying
}
}
decLogger.logFailure();
// nothing works.
throw new GeneralSecurityException("decryption failed");
}
}
DeterministicAeadWrapper() {}
@Override
public DeterministicAead wrap(final PrimitiveSet primitives)
throws GeneralSecurityException {
PrefixMap.Builder builder = new PrefixMap.Builder<>();
KeysetHandleInterface handle = primitives.getKeysetHandle();
for (int i = 0; i < handle.size(); i++) {
KeysetHandleInterface.Entry entry = handle.getAt(i);
DeterministicAead deterministicAead = primitives.getPrimitiveForEntry(entry);
builder.put(
getOutputPrefix(entry.getKey()),
new DeterministicAeadWithId(deterministicAead, entry.getId()));
}
MonitoringClient.Logger encLogger;
MonitoringClient.Logger decLogger;
if (!primitives.getAnnotations().isEmpty()) {
MonitoringClient client = MutableMonitoringRegistry.globalInstance().getMonitoringClient();
encLogger = client.createLogger(handle, primitives.getAnnotations(), "daead", "encrypt");
decLogger = client.createLogger(handle, primitives.getAnnotations(), "daead", "decrypt");
} else {
encLogger = MonitoringUtil.DO_NOTHING_LOGGER;
decLogger = MonitoringUtil.DO_NOTHING_LOGGER;
}
return new WrappedDeterministicAead(
new DeterministicAeadWithId(
primitives.getPrimitiveForEntry(handle.getPrimary()), handle.getPrimary().getId()),
builder.build(),
encLogger,
decLogger);
}
@Override
public Class getPrimitiveClass() {
return DeterministicAead.class;
}
@Override
public Class getInputPrimitiveClass() {
return DeterministicAead.class;
}
public static void register() throws GeneralSecurityException {
MutablePrimitiveRegistry.globalInstance().registerPrimitiveWrapper(WRAPPER);
MutablePrimitiveRegistry.globalInstance()
.registerPrimitiveConstructor(LEGACY_FULL_DAEAD_PRIMITIVE_CONSTRUCTOR);
}
/**
* registerToInternalPrimitiveRegistry is a non-public method (it takes an argument of an
* internal-only type) registering an instance of {@code DeterministicAeadWrapper} to the provided
* {@code PrimitiveRegistry.Builder}.
*/
public static void registerToInternalPrimitiveRegistry(
PrimitiveRegistry.Builder primitiveRegistryBuilder) throws GeneralSecurityException {
primitiveRegistryBuilder.registerPrimitiveWrapper(WRAPPER);
}
}