// 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/hybrid/hybrid_decrypt_wrapper.h"
#include <string>
#include <utility>
#include "absl/status/status.h"
#include "tink/crypto_format.h"
#include "tink/hybrid_decrypt.h"
#include "tink/internal/monitoring_util.h"
#include "tink/internal/registry_impl.h"
#include "tink/internal/util.h"
#include "tink/monitoring/monitoring.h"
#include "tink/primitive_set.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
namespace {
constexpr absl::string_view kPrimitive = "hybrid_decrypt";
constexpr absl::string_view kDecryptApi = "decrypt";
class HybridDecryptSetWrapper : public HybridDecrypt {
public:
explicit HybridDecryptSetWrapper(
std::unique_ptr<PrimitiveSet<HybridDecrypt>> hybrid_decrypt_set,
std::unique_ptr<MonitoringClient> monitoring_decryption_client = nullptr)
: hybrid_decrypt_set_(std::move(hybrid_decrypt_set)),
monitoring_decryption_client_(std::move(monitoring_decryption_client)) {
}
crypto::tink::util::StatusOr<std::string> Decrypt(
absl::string_view ciphertext,
absl::string_view context_info) const override;
~HybridDecryptSetWrapper() override {}
private:
std::unique_ptr<PrimitiveSet<HybridDecrypt>> hybrid_decrypt_set_;
std::unique_ptr<MonitoringClient> monitoring_decryption_client_;
};
util::StatusOr<std::string> HybridDecryptSetWrapper::Decrypt(
absl::string_view ciphertext, absl::string_view context_info) const {
// BoringSSL expects a non-null pointer for context_info,
// regardless of whether the size is 0.
context_info = internal::EnsureStringNonNull(context_info);
if (ciphertext.length() > CryptoFormat::kNonRawPrefixSize) {
absl::string_view key_id =
ciphertext.substr(0, CryptoFormat::kNonRawPrefixSize);
auto primitives_result = hybrid_decrypt_set_->get_primitives(key_id);
if (primitives_result.ok()) {
absl::string_view raw_ciphertext =
ciphertext.substr(CryptoFormat::kNonRawPrefixSize);
for (auto& hybrid_decrypt_entry : *(primitives_result.value())) {
HybridDecrypt& hybrid_decrypt = hybrid_decrypt_entry->get_primitive();
auto decrypt_result =
hybrid_decrypt.Decrypt(raw_ciphertext, context_info);
if (decrypt_result.ok()) {
if (monitoring_decryption_client_ != nullptr) {
monitoring_decryption_client_->Log(
hybrid_decrypt_entry->get_key_id(), ciphertext.size());
}
return std::move(decrypt_result.value());
} else {
// LOG that a matching key didn't decrypt the ciphertext.
}
}
}
}
// No matching key succeeded with decryption, try all RAW keys.
auto raw_primitives_result = hybrid_decrypt_set_->get_raw_primitives();
if (raw_primitives_result.ok()) {
for (auto& hybrid_decrypt_entry : *(raw_primitives_result.value())) {
HybridDecrypt& hybrid_decrypt = hybrid_decrypt_entry->get_primitive();
auto decrypt_result = hybrid_decrypt.Decrypt(ciphertext, context_info);
if (decrypt_result.ok()) {
return std::move(decrypt_result.value());
}
}
}
if (monitoring_decryption_client_ != nullptr) {
monitoring_decryption_client_->LogFailure();
}
return util::Status(absl::StatusCode::kInvalidArgument, "decryption failed");
}
util::Status Validate(PrimitiveSet<HybridDecrypt>* hybrid_decrypt_set) {
if (hybrid_decrypt_set == nullptr) {
return util::Status(absl::StatusCode::kInternal,
"hybrid_decrypt_set must be non-NULL");
}
if (hybrid_decrypt_set->get_primary() == nullptr) {
return util::Status(absl::StatusCode::kInvalidArgument,
"hybrid_decrypt_set has no primary");
}
return util::OkStatus();
}
} // anonymous namespace
// static
util::StatusOr<std::unique_ptr<HybridDecrypt>> HybridDecryptWrapper::Wrap(
std::unique_ptr<PrimitiveSet<HybridDecrypt>> primitive_set) const {
util::Status status = Validate(primitive_set.get());
if (!status.ok()) return status;
MonitoringClientFactory* const monitoring_factory =
internal::RegistryImpl::GlobalInstance().GetMonitoringClientFactory();
// Monitoring is not enabled. Create a wrapper without monitoring clients.
if (monitoring_factory == nullptr) {
return {
absl::make_unique<HybridDecryptSetWrapper>(std::move(primitive_set))};
}
util::StatusOr<MonitoringKeySetInfo> keyset_info =
internal::MonitoringKeySetInfoFromPrimitiveSet(*primitive_set);
if (!keyset_info.ok()) {
return keyset_info.status();
}
util::StatusOr<std::unique_ptr<MonitoringClient>>
monitoring_decryption_client = monitoring_factory->New(
MonitoringContext(kPrimitive, kDecryptApi, *keyset_info));
if (!monitoring_decryption_client.ok()) {
return monitoring_decryption_client.status();
}
return {absl::make_unique<HybridDecryptSetWrapper>(
std::move(primitive_set), *std::move(monitoring_decryption_client))};
}
} // namespace tink
} // namespace crypto