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Tink is a small cryptographic library that provides a safe, simple, agile and fast way to accomplish some common cryptographic tasks.
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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.streamingaead;

import com.google.crypto.tink.StreamingAead;
import com.google.crypto.tink.internal.KeysetHandleInterface;
import com.google.crypto.tink.internal.LegacyProtoKey;
import com.google.crypto.tink.internal.MutablePrimitiveRegistry;
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.streamingaead.internal.LegacyFullStreamingAead;
import java.security.GeneralSecurityException;
import java.util.ArrayList;
import java.util.List;

/**
 * StreamingAeadWrapper is the implementation of PrimitiveWrapper for the StreamingAead primitive.
 *
 * The returned primitive works with a keyset (rather than a single key). To encrypt a plaintext,
 * it uses the primary key in the keyset. To decrypt, the primitive tries the enabled keys from the
 * keyset to select the right key for decryption. All keys in a keyset of StreamingAead have type
 * {@link com.google.crypto.tink.proto.OutputPrefixType#RAW}.
 */
public class StreamingAeadWrapper implements PrimitiveWrapper {

  private static final StreamingAeadWrapper WRAPPER = new StreamingAeadWrapper();
  private static final PrimitiveConstructor
      LEGACY_FULL_STREAMING_AEAD_PRIMITIVE_CONSTRUCTOR =
          PrimitiveConstructor.create(
              LegacyFullStreamingAead::create, LegacyProtoKey.class, StreamingAead.class);

  StreamingAeadWrapper() {}

  /**
   * @return a StreamingAead primitive from a {@code keysetHandle}.
   * @throws GeneralSecurityException
   */
  @Override
  public StreamingAead wrap(final PrimitiveSet primitives)
      throws GeneralSecurityException {
    List allStreamingAeads = new ArrayList<>();
    KeysetHandleInterface handle = primitives.getKeysetHandle();
    for (int i = 0; i < handle.size(); i++) {
      KeysetHandleInterface.Entry entry = handle.getAt(i);
      StreamingAead streamingAead = primitives.getPrimitiveForEntry(entry);
      allStreamingAeads.add(streamingAead);
    }
    KeysetHandleInterface.Entry primaryEntry = handle.getPrimary();
    if (primaryEntry == null) {
      throw new GeneralSecurityException("No primary set");
    }
    StreamingAead primaryStreamingAead = primitives.getPrimitiveForEntry(primaryEntry);
    if (primaryStreamingAead == null) {
      throw new GeneralSecurityException("No primary set");
    }

    return new StreamingAeadHelper(allStreamingAeads, primaryStreamingAead);
  }

  @Override
  public Class getPrimitiveClass() {
    return StreamingAead.class;
  }

  @Override
  public Class getInputPrimitiveClass() {
    return StreamingAead.class;
  }

  public static void register() throws GeneralSecurityException {
    MutablePrimitiveRegistry.globalInstance().registerPrimitiveWrapper(WRAPPER);
    MutablePrimitiveRegistry.globalInstance()
        .registerPrimitiveConstructor(LEGACY_FULL_STREAMING_AEAD_PRIMITIVE_CONSTRUCTOR);
  }

  /**
   * registerToInternalPrimitiveRegistry is a non-public method (it takes an argument of an
   * internal-only type) registering an instance of {@code StreamingAeadWrapper} to the provided
   * {@code PrimitiveRegistry.Builder}.
   */
  public static void registerToInternalPrimitiveRegistry(
      PrimitiveRegistry.Builder primitiveRegistryBuilder) throws GeneralSecurityException {
    primitiveRegistryBuilder.registerPrimitiveWrapper(WRAPPER);
  }
}