| // 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. |
| // |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| #ifndef TINK_PRF_HKDF_PRF_KEY_MANAGER_H_ |
| #define TINK_PRF_HKDF_PRF_KEY_MANAGER_H_ |
| |
| #include <string> |
| |
| #include "absl/memory/memory.h" |
| #include "absl/strings/str_cat.h" |
| #include "tink/core/key_type_manager.h" |
| #include "tink/input_stream.h" |
| #include "tink/prf/prf_set.h" |
| #include "tink/subtle/prf/hkdf_streaming_prf.h" |
| #include "tink/subtle/prf/prf_set_util.h" |
| #include "tink/subtle/prf/streaming_prf.h" |
| #include "tink/subtle/random.h" |
| #include "tink/util/constants.h" |
| #include "tink/util/enums.h" |
| #include "tink/util/input_stream_util.h" |
| #include "tink/util/secret_data.h" |
| #include "tink/util/status.h" |
| #include "tink/util/statusor.h" |
| #include "tink/util/validation.h" |
| #include "proto/common.pb.h" |
| #include "proto/hkdf_prf.pb.h" |
| #include "proto/tink.pb.h" |
| |
| namespace crypto { |
| namespace tink { |
| |
| class HkdfPrfKeyManager |
| : public KeyTypeManager<google::crypto::tink::HkdfPrfKey, |
| google::crypto::tink::HkdfPrfKeyFormat, |
| List<StreamingPrf, PrfSet>> { |
| public: |
| class StreamingPrfFactory : public PrimitiveFactory<StreamingPrf> { |
| crypto::tink::util::StatusOr<std::unique_ptr<StreamingPrf>> Create( |
| const google::crypto::tink::HkdfPrfKey& key) const override { |
| return subtle::HkdfStreamingPrf::New( |
| crypto::tink::util::Enums::ProtoToSubtle(key.params().hash()), |
| util::SecretDataFromStringView(key.key_value()), key.params().salt()); |
| } |
| }; |
| |
| class PrfSetFactory : public PrimitiveFactory<PrfSet> { |
| crypto::tink::util::StatusOr<std::unique_ptr<PrfSet>> Create( |
| const google::crypto::tink::HkdfPrfKey& key) const override { |
| auto hkdf_result = subtle::HkdfStreamingPrf::New( |
| crypto::tink::util::Enums::ProtoToSubtle(key.params().hash()), |
| util::SecretDataFromStringView(key.key_value()), key.params().salt()); |
| if (!hkdf_result.ok()) { |
| return hkdf_result.status(); |
| } |
| return subtle::CreatePrfSetFromPrf(subtle::CreatePrfFromStreamingPrf( |
| std::move(hkdf_result.ValueOrDie()))); |
| } |
| }; |
| |
| HkdfPrfKeyManager() |
| : KeyTypeManager(absl::make_unique<StreamingPrfFactory>(), |
| absl::make_unique<PrfSetFactory>()) {} |
| |
| uint32_t get_version() const override { return 0; } |
| |
| google::crypto::tink::KeyData::KeyMaterialType key_material_type() |
| const override { |
| return google::crypto::tink::KeyData::SYMMETRIC; |
| } |
| |
| const std::string& get_key_type() const override { return key_type_; } |
| |
| crypto::tink::util::Status ValidateKey( |
| const google::crypto::tink::HkdfPrfKey& key) const override { |
| crypto::tink::util::Status status = |
| ValidateVersion(key.version(), get_version()); |
| if (!status.ok()) return status; |
| status = ValidateKeySize(key.key_value().size()); |
| if (!status.ok()) return status; |
| return ValidateParams(key.params()); |
| } |
| |
| crypto::tink::util::Status ValidateKeyFormat( |
| const google::crypto::tink::HkdfPrfKeyFormat& key_format) const override { |
| crypto::tink::util::Status status = |
| ValidateVersion(key_format.version(), get_version()); |
| if (!status.ok()) return status; |
| status = ValidateKeySize(key_format.key_size()); |
| if (!status.ok()) return status; |
| return ValidateParams(key_format.params()); |
| } |
| |
| crypto::tink::util::StatusOr<google::crypto::tink::HkdfPrfKey> CreateKey( |
| const google::crypto::tink::HkdfPrfKeyFormat& key_format) const override { |
| google::crypto::tink::HkdfPrfKey key; |
| key.set_version(get_version()); |
| *key.mutable_params() = key_format.params(); |
| key.set_key_value( |
| crypto::tink::subtle::Random::GetRandomBytes(key_format.key_size())); |
| return key; |
| } |
| |
| crypto::tink::util::StatusOr<google::crypto::tink::HkdfPrfKey> DeriveKey( |
| const google::crypto::tink::HkdfPrfKeyFormat& key_format, |
| InputStream* input_stream) const override { |
| auto status = ValidateKeyFormat(key_format); |
| if (!status.ok()) { |
| return status; |
| } |
| crypto::tink::util::StatusOr<std::string> randomness = |
| ReadBytesFromStream(key_format.key_size(), input_stream); |
| if (!randomness.ok()) { |
| return randomness.status(); |
| } |
| google::crypto::tink::HkdfPrfKey key; |
| key.set_version(get_version()); |
| *key.mutable_params() = key_format.params(); |
| key.set_key_value(randomness.ValueOrDie()); |
| return key; |
| } |
| |
| private: |
| crypto::tink::util::Status ValidateKeySize(int key_size) const { |
| if (key_size < kMinKeySizeBytes) { |
| return crypto::tink::util::Status( |
| util::error::INVALID_ARGUMENT, |
| "Invalid HkdfPrfKey: key_value is too short."); |
| } |
| return crypto::tink::util::Status::OK; |
| } |
| |
| crypto::tink::util::Status ValidateParams( |
| const google::crypto::tink::HkdfPrfParams& params) const { |
| // Omitting SHA1 for the moment; there seems to be no reason to allow it. |
| if (params.hash() != google::crypto::tink::HashType::SHA256 && |
| params.hash() != google::crypto::tink::HashType::SHA512) { |
| return crypto::tink::util::Status( |
| util::error::INVALID_ARGUMENT, |
| "Invalid HkdfPrfKey: unsupported hash."); |
| } |
| return crypto::tink::util::Status::OK; |
| } |
| |
| // We use a somewhat larger minimum key size than usual, because PRFs might be |
| // used by many users, in which case the security can degrade by a factor |
| // depending on the number of users. (Discussed for example in |
| // https://eprint.iacr.org/2012/159) |
| const int kMinKeySizeBytes = 32; |
| const std::string key_type_ = absl::StrCat( |
| kTypeGoogleapisCom, google::crypto::tink::HkdfPrfKey().GetTypeName()); |
| }; |
| |
| } // namespace tink |
| } // namespace crypto |
| |
| #endif // TINK_PRF_HKDF_PRF_KEY_MANAGER_H_ |