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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 2023 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.internal;

import static com.google.crypto.tink.internal.Util.toBytesFromPrintableAscii;

import com.google.crypto.tink.AccessesPartialKey;
import com.google.crypto.tink.SecretKeyAccess;
import com.google.crypto.tink.daead.AesSivKey;
import com.google.crypto.tink.daead.AesSivParameters;
import com.google.crypto.tink.internal.KeyParser;
import com.google.crypto.tink.internal.KeySerializer;
import com.google.crypto.tink.internal.MutableSerializationRegistry;
import com.google.crypto.tink.internal.ParametersParser;
import com.google.crypto.tink.internal.ParametersSerializer;
import com.google.crypto.tink.internal.ProtoKeySerialization;
import com.google.crypto.tink.internal.ProtoParametersSerialization;
import com.google.crypto.tink.proto.KeyData.KeyMaterialType;
import com.google.crypto.tink.proto.KeyTemplate;
import com.google.crypto.tink.proto.OutputPrefixType;
import com.google.crypto.tink.util.Bytes;
import com.google.crypto.tink.util.SecretBytes;
import com.google.protobuf.ByteString;
import com.google.protobuf.ExtensionRegistryLite;
import com.google.protobuf.InvalidProtocolBufferException;
import java.security.GeneralSecurityException;
import java.util.Collections;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.Nullable;

/** Methods to serialize and parse {@link AesSivKey} objects and {@link AesSivParameters} objects */
@AccessesPartialKey
@SuppressWarnings("UnnecessarilyFullyQualified") // Fully specifying proto types is more readable
public final class AesSivProtoSerialization {
  private static final String TYPE_URL = "type.googleapis.com/google.crypto.tink.AesSivKey";
  private static final Bytes TYPE_URL_BYTES = toBytesFromPrintableAscii(TYPE_URL);

  private static final ParametersSerializer
      PARAMETERS_SERIALIZER =
          ParametersSerializer.create(
              AesSivProtoSerialization::serializeParameters,
              AesSivParameters.class,
              ProtoParametersSerialization.class);

  private static final ParametersParser PARAMETERS_PARSER =
      ParametersParser.create(
          AesSivProtoSerialization::parseParameters,
          TYPE_URL_BYTES,
          ProtoParametersSerialization.class);

  private static final KeySerializer KEY_SERIALIZER =
      KeySerializer.create(
          AesSivProtoSerialization::serializeKey, AesSivKey.class, ProtoKeySerialization.class);

  private static final KeyParser KEY_PARSER =
      KeyParser.create(
          AesSivProtoSerialization::parseKey, TYPE_URL_BYTES, ProtoKeySerialization.class);

  private static Map createVariantToOutputPrefixMap() {
    Map result = new HashMap<>();
    result.put(AesSivParameters.Variant.NO_PREFIX, OutputPrefixType.RAW);
    result.put(AesSivParameters.Variant.TINK, OutputPrefixType.TINK);
    result.put(AesSivParameters.Variant.CRUNCHY, OutputPrefixType.CRUNCHY);
    return Collections.unmodifiableMap(result);
  }

  private static Map createOutputPrefixToVariantMap() {
    Map result = new EnumMap<>(OutputPrefixType.class);
    result.put(OutputPrefixType.RAW, AesSivParameters.Variant.NO_PREFIX);
    result.put(OutputPrefixType.TINK, AesSivParameters.Variant.TINK);
    result.put(OutputPrefixType.CRUNCHY, AesSivParameters.Variant.CRUNCHY);
    /** Parse LEGACY prefix to CRUNCHY, since they act the same for this type of key */
    result.put(OutputPrefixType.LEGACY, AesSivParameters.Variant.CRUNCHY);
    return Collections.unmodifiableMap(result);
  }

  // This map is constructed using Collections.unmodifiableMap
  @SuppressWarnings("Immutable")
  private static final Map variantsToOutputPrefixMap =
      createVariantToOutputPrefixMap();

  // This map is constructed using Collections.unmodifiableMap
  @SuppressWarnings("Immutable")
  private static final Map outputPrefixToVariantMap =
      createOutputPrefixToVariantMap();

  private static OutputPrefixType toProtoOutputPrefixType(AesSivParameters.Variant variant)
      throws GeneralSecurityException {
    if (variantsToOutputPrefixMap.containsKey(variant)) {
      return variantsToOutputPrefixMap.get(variant);
    }
    throw new GeneralSecurityException("Unable to serialize variant: " + variant);
  }

  private static AesSivParameters.Variant toVariant(OutputPrefixType outputPrefixType)
      throws GeneralSecurityException {
    if (outputPrefixToVariantMap.containsKey(outputPrefixType)) {
      return outputPrefixToVariantMap.get(outputPrefixType);
    }
    throw new GeneralSecurityException(
        "Unable to parse OutputPrefixType: " + outputPrefixType.getNumber());
  }

  private static ProtoParametersSerialization serializeParameters(AesSivParameters parameters)
      throws GeneralSecurityException {
    return ProtoParametersSerialization.create(
        KeyTemplate.newBuilder()
            .setTypeUrl(TYPE_URL)
            .setValue(
                com.google.crypto.tink.proto.AesSivKeyFormat.newBuilder()
                    .setKeySize(parameters.getKeySizeBytes())
                    .build()
                    .toByteString())
            .setOutputPrefixType(toProtoOutputPrefixType(parameters.getVariant()))
            .build());
  }

  private static ProtoKeySerialization serializeKey(AesSivKey key, @Nullable SecretKeyAccess access)
      throws GeneralSecurityException {
    return ProtoKeySerialization.create(
        TYPE_URL,
        com.google.crypto.tink.proto.AesSivKey.newBuilder()
            .setKeyValue(
                ByteString.copyFrom(
                    key.getKeyBytes().toByteArray(SecretKeyAccess.requireAccess(access))))
            .build()
            .toByteString(),
        KeyMaterialType.SYMMETRIC,
        toProtoOutputPrefixType(key.getParameters().getVariant()),
        key.getIdRequirementOrNull());
  }

  private static AesSivParameters parseParameters(ProtoParametersSerialization serialization)
      throws GeneralSecurityException {
    if (!serialization.getKeyTemplate().getTypeUrl().equals(TYPE_URL)) {
      throw new IllegalArgumentException(
          "Wrong type URL in call to AesSivParameters.parseParameters: "
              + serialization.getKeyTemplate().getTypeUrl());
    }
    com.google.crypto.tink.proto.AesSivKeyFormat format;
    try {
      format =
          com.google.crypto.tink.proto.AesSivKeyFormat.parseFrom(
              serialization.getKeyTemplate().getValue(), ExtensionRegistryLite.getEmptyRegistry());
      if (format.getVersion() != 0) {
        throw new GeneralSecurityException("Only version 0 keys are accepted");
      }
    } catch (InvalidProtocolBufferException e) {
      throw new GeneralSecurityException("Parsing AesSivParameters failed: ", e);
    }
    return AesSivParameters.builder()
        .setKeySizeBytes(format.getKeySize())
        .setVariant(toVariant(serialization.getKeyTemplate().getOutputPrefixType()))
        .build();
  }

  @SuppressWarnings("UnusedException") // Prevents leaking key material
  private static AesSivKey parseKey(
      ProtoKeySerialization serialization, @Nullable SecretKeyAccess access)
      throws GeneralSecurityException {
    if (!serialization.getTypeUrl().equals(TYPE_URL)) {
      throw new IllegalArgumentException(
          "Wrong type URL in call to AesSivParameters.parseParameters");
    }
    try {
      com.google.crypto.tink.proto.AesSivKey protoKey =
          com.google.crypto.tink.proto.AesSivKey.parseFrom(
              serialization.getValue(), ExtensionRegistryLite.getEmptyRegistry());
      if (protoKey.getVersion() != 0) {
        throw new GeneralSecurityException("Only version 0 keys are accepted");
      }
      AesSivParameters parameters =
          AesSivParameters.builder()
              .setKeySizeBytes(protoKey.getKeyValue().size())
              .setVariant(toVariant(serialization.getOutputPrefixType()))
              .build();
      return AesSivKey.builder()
          .setParameters(parameters)
          .setKeyBytes(
              SecretBytes.copyFrom(
                  protoKey.getKeyValue().toByteArray(), SecretKeyAccess.requireAccess(access)))
          .setIdRequirement(serialization.getIdRequirementOrNull())
          .build();
    } catch (InvalidProtocolBufferException e) {
      throw new GeneralSecurityException("Parsing AesSivKey failed");
    }
  }

  public static void register() throws GeneralSecurityException {
    register(MutableSerializationRegistry.globalInstance());
  }

  public static void register(MutableSerializationRegistry registry)
      throws GeneralSecurityException {
    registry.registerParametersSerializer(PARAMETERS_SERIALIZER);
    registry.registerParametersParser(PARAMETERS_PARSER);
    registry.registerKeySerializer(KEY_SERIALIZER);
    registry.registerKeyParser(KEY_PARSER);
  }

  private AesSivProtoSerialization() {}
}