// Copyright 2017 Google Inc.
//
// 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.hybrid;

import com.google.crypto.tink.HybridEncrypt;
import com.google.crypto.tink.KeyTypeManager;
import com.google.crypto.tink.proto.EciesAeadHkdfParams;
import com.google.crypto.tink.proto.EciesAeadHkdfPublicKey;
import com.google.crypto.tink.proto.EciesHkdfKemParams;
import com.google.crypto.tink.proto.KeyData.KeyMaterialType;
import com.google.crypto.tink.subtle.EciesAeadHkdfDemHelper;
import com.google.crypto.tink.subtle.EciesAeadHkdfHybridEncrypt;
import com.google.crypto.tink.subtle.EllipticCurves;
import com.google.crypto.tink.subtle.Validators;
import com.google.protobuf.ByteString;
import com.google.protobuf.ExtensionRegistryLite;
import com.google.protobuf.InvalidProtocolBufferException;
import java.security.GeneralSecurityException;
import java.security.interfaces.ECPublicKey;

/**
 * This key manager produces new instances of {@code EciesAeadHkdfHybridEncrypt}. It doesn't support
 * key generation.
 */
class EciesAeadHkdfPublicKeyManager extends KeyTypeManager<EciesAeadHkdfPublicKey> {
  public EciesAeadHkdfPublicKeyManager() {
    super(
        EciesAeadHkdfPublicKey.class,
        new PrimitiveFactory<HybridEncrypt, EciesAeadHkdfPublicKey>(HybridEncrypt.class) {
          @Override
          public HybridEncrypt getPrimitive(EciesAeadHkdfPublicKey recipientKeyProto)
              throws GeneralSecurityException {
            EciesAeadHkdfParams eciesParams = recipientKeyProto.getParams();
            EciesHkdfKemParams kemParams = eciesParams.getKemParams();
            ECPublicKey recipientPublicKey =
                EllipticCurves.getEcPublicKey(
                    HybridUtil.toCurveType(kemParams.getCurveType()),
                    recipientKeyProto.getX().toByteArray(),
                    recipientKeyProto.getY().toByteArray());
            EciesAeadHkdfDemHelper demHelper =
                new RegistryEciesAeadHkdfDemHelper(eciesParams.getDemParams().getAeadDem());
            return new EciesAeadHkdfHybridEncrypt(
                recipientPublicKey,
                kemParams.getHkdfSalt().toByteArray(),
                HybridUtil.toHmacAlgo(kemParams.getHkdfHashType()),
                HybridUtil.toPointFormatType(eciesParams.getEcPointFormat()),
                demHelper);
          }
        });
  }

  @Override
  public String getKeyType() {
    return "type.googleapis.com/google.crypto.tink.EciesAeadHkdfPublicKey";
  }

  @Override
  public int getVersion() {
    return 0;
  }

  @Override
  public KeyMaterialType keyMaterialType() {
    return KeyMaterialType.ASYMMETRIC_PUBLIC;
  }

  @Override
  public EciesAeadHkdfPublicKey parseKey(ByteString byteString)
      throws InvalidProtocolBufferException {
    return EciesAeadHkdfPublicKey.parseFrom(byteString, ExtensionRegistryLite.getEmptyRegistry());
  }

  @Override
  public void validateKey(EciesAeadHkdfPublicKey key) throws GeneralSecurityException {
    // TODO(b/74251423): add more checks.
    Validators.validateVersion(key.getVersion(), getVersion());
    HybridUtil.validate(key.getParams());
  }
}