cc/signature/ecdsa_sign_key_manager.cc

// 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.
//
///////////////////////////////////////////////////////////////////////////////

#include "tink/signature/ecdsa_sign_key_manager.h"

#include "absl/strings/string_view.h"
#include "absl/memory/memory.h"
#include "tink/core/key_manager_base.h"
#include "tink/public_key_sign.h"
#include "tink/key_manager.h"
#include "tink/signature/ecdsa_verify_key_manager.h"
#include "tink/subtle/ecdsa_sign_boringssl.h"
#include "tink/subtle/subtle_util_boringssl.h"
#include "tink/util/enums.h"
#include "tink/util/errors.h"
#include "tink/util/protobuf_helper.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
#include "tink/util/validation.h"
#include "proto/ecdsa.pb.h"
#include "proto/tink.pb.h"

namespace crypto {
namespace tink {

using google::crypto::tink::EcdsaKeyFormat;
using google::crypto::tink::EcdsaPrivateKey;
using google::crypto::tink::EcdsaPublicKey;
using google::crypto::tink::KeyData;
using portable_proto::MessageLite;
using crypto::tink::util::Enums;
using crypto::tink::util::Status;
using crypto::tink::util::StatusOr;

class EcdsaPrivateKeyFactory
    : public PrivateKeyFactory,
      public KeyFactoryBase<EcdsaPrivateKey, EcdsaKeyFormat> {
 public:
  EcdsaPrivateKeyFactory() {}

  KeyData::KeyMaterialType key_material_type() const override {
    return KeyData::ASYMMETRIC_PRIVATE;
  }

  // Returns KeyData proto that contains EcdsaPublicKey
  // extracted from the given serialized_private_key, which must contain
  // EcdsaPrivateKey-proto.
  crypto::tink::util::StatusOr<std::unique_ptr<google::crypto::tink::KeyData>>
  GetPublicKeyData(absl::string_view serialized_private_key) const override;

 protected:
  StatusOr<std::unique_ptr<EcdsaPrivateKey>> NewKeyFromFormat(
      const EcdsaKeyFormat& ecdsa_key_format) const override;
};

StatusOr<std::unique_ptr<EcdsaPrivateKey>>
EcdsaPrivateKeyFactory::NewKeyFromFormat(
    const EcdsaKeyFormat& ecdsa_key_format) const {
  Status status = EcdsaVerifyKeyManager::Validate(ecdsa_key_format);
  if (!status.ok()) return status;

  // Generate new EC key.
  auto ec_key_result = subtle::SubtleUtilBoringSSL::GetNewEcKey(
      util::Enums::ProtoToSubtle(ecdsa_key_format.params().curve()));
  if (!ec_key_result.ok()) return ec_key_result.status();
  auto ec_key = ec_key_result.ValueOrDie();

  // Build EcdsaPrivateKey.
  std::unique_ptr<EcdsaPrivateKey> ecdsa_private_key(
      new EcdsaPrivateKey());
  ecdsa_private_key->set_version(EcdsaSignKeyManager::kVersion);
  ecdsa_private_key->set_key_value(ec_key.priv);
  auto ecdsa_public_key = ecdsa_private_key->mutable_public_key();
  ecdsa_public_key->set_version(EcdsaSignKeyManager::kVersion);
  ecdsa_public_key->set_x(ec_key.pub_x);
  ecdsa_public_key->set_y(ec_key.pub_y);
  *(ecdsa_public_key->mutable_params()) = ecdsa_key_format.params();

  return absl::implicit_cast<StatusOr<std::unique_ptr<EcdsaPrivateKey>>>(
        std::move(ecdsa_private_key));
}

StatusOr<std::unique_ptr<KeyData>>
EcdsaPrivateKeyFactory::GetPublicKeyData(
    absl::string_view serialized_private_key) const {
  EcdsaPrivateKey private_key;
  if (!private_key.ParseFromString(std::string(serialized_private_key))) {
    return Status(util::error::INVALID_ARGUMENT,
                  absl::StrCat("Could not parse the passed string as proto '",
                               EcdsaVerifyKeyManager::static_key_type(), "'."));
  }
  auto status = EcdsaSignKeyManager::Validate(private_key);
  if (!status.ok()) return status;
  auto key_data = absl::make_unique<KeyData>();
  key_data->set_type_url(EcdsaVerifyKeyManager::static_key_type());
  key_data->set_value(private_key.public_key().SerializeAsString());
  key_data->set_key_material_type(KeyData::ASYMMETRIC_PUBLIC);
  return std::move(key_data);
}

constexpr uint32_t EcdsaSignKeyManager::kVersion;

EcdsaSignKeyManager::EcdsaSignKeyManager()
    : key_factory_(absl::make_unique<EcdsaPrivateKeyFactory>()) {}

const KeyFactory& EcdsaSignKeyManager::get_key_factory() const {
  return *key_factory_;
}

uint32_t EcdsaSignKeyManager::get_version() const {
  return kVersion;
}

StatusOr<std::unique_ptr<PublicKeySign>>
EcdsaSignKeyManager::GetPrimitiveFromKey(
    const EcdsaPrivateKey& ecdsa_private_key) const {
  Status status = Validate(ecdsa_private_key);
  if (!status.ok()) return status;
  const EcdsaPublicKey& public_key = ecdsa_private_key.public_key();
  subtle::SubtleUtilBoringSSL::EcKey ec_key;
  ec_key.curve = Enums::ProtoToSubtle(public_key.params().curve());
  ec_key.pub_x = public_key.x();
  ec_key.pub_y = public_key.y();
  ec_key.priv = ecdsa_private_key.key_value();
  auto ecdsa_result = subtle::EcdsaSignBoringSsl::New(
      ec_key, Enums::ProtoToSubtle(public_key.params().hash_type()),
      Enums::ProtoToSubtle(public_key.params().encoding()));
  if (!ecdsa_result.ok()) return ecdsa_result.status();
  std::unique_ptr<PublicKeySign> ecdsa(ecdsa_result.ValueOrDie().release());
  return std::move(ecdsa);
}

// static
Status EcdsaSignKeyManager::Validate(
    const EcdsaPrivateKey& key) {
  Status status = ValidateVersion(key.version(), kVersion);
  if (!status.ok()) return status;
  return EcdsaVerifyKeyManager::Validate(key.public_key().params());
}

}  // namespace tink
}  // namespace crypto