| // Copyright 2021 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. |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #include "tink/experimental/pqcrypto/kem/cecpq2_aead_hkdf_dem_helper.h" |
| |
| #include <string> |
| #include <utility> |
| |
| #include "absl/memory/memory.h" |
| #include "absl/status/status.h" |
| #include "tink/aead.h" |
| #include "tink/deterministic_aead.h" |
| #include "tink/registry.h" |
| #include "tink/util/errors.h" |
| #include "tink/util/istream_input_stream.h" |
| #include "tink/util/protobuf_helper.h" |
| #include "tink/util/secret_data.h" |
| #include "tink/util/statusor.h" |
| #include "proto/tink.pb.h" |
| |
| namespace crypto { |
| namespace tink { |
| namespace { |
| |
| using ::crypto::tink::subtle::AeadOrDaead; |
| using ::google::crypto::tink::KeyTemplate; |
| |
| // Internal implementaton of the Cecpq2AeadHkdfDemHelper class, parametrized by |
| // the Primitive used for data encapsulation (i.e Aead or DeterministicAead). |
| template <class EncryptionPrimitive> |
| class Cecpq2AeadHkdfDemHelperImpl : public Cecpq2AeadHkdfDemHelper { |
| public: |
| explicit Cecpq2AeadHkdfDemHelperImpl( |
| const google::crypto::tink::KeyTemplate& key_template) |
| : key_template_(key_template) {} |
| |
| crypto::tink::util::StatusOr< |
| std::unique_ptr<crypto::tink::subtle::AeadOrDaead>> |
| GetAeadOrDaead(const util::SecretData& seed) const override { |
| if (seed.size() < 32) { |
| return util::Status(absl::StatusCode::kInternal, |
| "Seed length is smaller than 32 bytes " |
| "and thus not post-quantum secure."); |
| } |
| std::string seed_str(util::SecretDataAsStringView(seed)); |
| util::IstreamInputStream input_stream{ |
| absl::make_unique<std::stringstream>(seed_str)}; |
| auto key_or = internal::RegistryImpl::GlobalInstance().DeriveKey( |
| key_template_, &input_stream); |
| if (!key_or.ok()) return key_or.status(); |
| auto key = std::move(key_or).value(); |
| util::StatusOr<std::unique_ptr<EncryptionPrimitive>> primitive_or = |
| Registry::GetPrimitive<EncryptionPrimitive>(key); |
| if (!primitive_or.ok()) return primitive_or.status(); |
| return absl::make_unique<AeadOrDaead>(std::move(primitive_or.value())); |
| } |
| |
| crypto::tink::util::StatusOr<uint32_t> GetKeyMaterialSize() const override { |
| absl::string_view dem_type_url = key_template_.type_url(); |
| // For AES-SIV, two keys of 32 bytes each are needed |
| if (dem_type_url == "type.googleapis.com/google.crypto.tink.AesSivKey") { |
| return 64; |
| } else if ( |
| dem_type_url == "type.googleapis.com/google.crypto.tink.AesGcmKey" || |
| dem_type_url == |
| "type.googleapis.com/google.crypto.tink.XChaCha20Poly1305Key") { |
| return 32; |
| } else { |
| return ToStatusF(absl::StatusCode::kInvalidArgument, |
| "Unsupported DEM key type '%s'.", dem_type_url); |
| } |
| } |
| |
| private: |
| const google::crypto::tink::KeyTemplate key_template_; |
| }; |
| } // namespace |
| |
| // static |
| util::StatusOr<std::unique_ptr<const Cecpq2AeadHkdfDemHelper>> |
| Cecpq2AeadHkdfDemHelper::New(const KeyTemplate& dem_key_template) { |
| const std::string& dem_type_url = dem_key_template.type_url(); |
| if (dem_type_url == "type.googleapis.com/google.crypto.tink.AesGcmKey" || |
| dem_type_url == |
| "type.googleapis.com/google.crypto.tink.XChaCha20Poly1305Key") { |
| return { |
| absl::make_unique<Cecpq2AeadHkdfDemHelperImpl<Aead>>(dem_key_template)}; |
| } else if (dem_type_url == |
| "type.googleapis.com/google.crypto.tink.AesSivKey") { |
| return {absl::make_unique<Cecpq2AeadHkdfDemHelperImpl<DeterministicAead>>( |
| dem_key_template)}; |
| } |
| return ToStatusF(absl::StatusCode::kInvalidArgument, |
| "Unsupported DEM key type '%s'.", dem_type_url); |
| } |
| |
| } // namespace tink |
| } // namespace crypto |