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// Copyright 2019 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/streamingaead/decrypting_input_stream.h"
#include <algorithm>
#include <cstdint>
#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "absl/memory/memory.h"
#include "absl/status/status.h"
#include "absl/strings/string_view.h"
#include "tink/input_stream.h"
#include "tink/primitive_set.h"
#include "tink/streaming_aead.h"
#include "tink/streamingaead/buffered_input_stream.h"
#include "tink/streamingaead/shared_input_stream.h"
#include "tink/util/errors.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
namespace crypto {
namespace tink {
namespace streamingaead {
using crypto::tink::PrimitiveSet;
using crypto::tink::StreamingAead;
using util::Status;
using util::StatusOr;
using StreamingAeadEntry = PrimitiveSet<StreamingAead>::Entry<StreamingAead>;
// static
StatusOr<std::unique_ptr<InputStream>> DecryptingInputStream::New(
std::shared_ptr<PrimitiveSet<StreamingAead>> primitives,
std::unique_ptr<crypto::tink::InputStream> ciphertext_source,
absl::string_view associated_data) {
auto dec_stream = absl::WrapUnique(new DecryptingInputStream());
dec_stream->primitives_ = primitives;
dec_stream->buffered_ct_source_ =
std::make_shared<BufferedInputStream>(std::move(ciphertext_source));
dec_stream->associated_data_ = std::string(associated_data);
dec_stream->attempted_matching_ = false;
dec_stream->matching_stream_ = nullptr;
return {std::move(dec_stream)};
}
util::StatusOr<int> DecryptingInputStream::Next(const void** data) {
if (matching_stream_ != nullptr) {
return matching_stream_->Next(data);
}
if (attempted_matching_) {
return Status(absl::StatusCode::kInvalidArgument,
"Could not find a decrypter matching the ciphertext stream.");
}
// Matching has not been attempted yet, so try it now.
attempted_matching_ = true;
std::vector<StreamingAeadEntry*> all_primitives = primitives_->get_all();
for (const StreamingAeadEntry* entry : all_primitives) {
StreamingAead& streaming_aead = entry->get_primitive();
auto shared_ct =
std::make_unique<SharedInputStream>(buffered_ct_source_.get());
auto decrypting_stream_result = streaming_aead.NewDecryptingStream(
std::move(shared_ct), associated_data_);
if (decrypting_stream_result.ok()) {
auto next_result = decrypting_stream_result.value()->Next(data);
if (next_result.status().code() == absl::StatusCode::kOutOfRange ||
next_result.ok()) { // Found a match.
buffered_ct_source_->DisableRewinding();
matching_stream_ = std::move(decrypting_stream_result.value());
return next_result;
}
}
// Not a match, rewind and try the next primitive.
Status s = buffered_ct_source_->Rewind();
if (!s.ok()) {
return s;
}
}
return Status(absl::StatusCode::kInvalidArgument,
"Could not find a decrypter matching the ciphertext stream.");
}
void DecryptingInputStream::BackUp(int count) {
if (matching_stream_ != nullptr) {
matching_stream_->BackUp(count);
}
}
int64_t DecryptingInputStream::Position() const {
if (matching_stream_ != nullptr) {
return matching_stream_->Position();
}
return 0;
}
} // namespace streamingaead
} // namespace tink
} // namespace crypto