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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_random_access_stream.h"
#include <memory>
#include <utility>
#include <vector>
#include "absl/memory/memory.h"
#include "absl/status/status.h"
#include "absl/synchronization/mutex.h"
#include "tink/primitive_set.h"
#include "tink/random_access_stream.h"
#include "tink/streaming_aead.h"
#include "tink/streamingaead/shared_random_access_stream.h"
#include "tink/util/buffer.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<RandomAccessStream>> DecryptingRandomAccessStream::New(
std::shared_ptr<PrimitiveSet<StreamingAead>> primitives,
std::unique_ptr<crypto::tink::RandomAccessStream> ciphertext_source,
absl::string_view associated_data) {
if (primitives == nullptr) {
return Status(absl::StatusCode::kInvalidArgument,
"primitives must be non-null.");
}
if (ciphertext_source == nullptr) {
return Status(absl::StatusCode::kInvalidArgument,
"ciphertext_source must be non-null.");
}
return {absl::WrapUnique(new DecryptingRandomAccessStream(
primitives, std::move(ciphertext_source), associated_data))};
}
util::Status DecryptingRandomAccessStream::PRead(
int64_t position, int count,
crypto::tink::util::Buffer* dest_buffer) {
{ // "fast-track": quickly proceed if matching has been attempted/found.
if (dest_buffer == nullptr) {
return util::Status(absl::StatusCode::kInvalidArgument,
"dest_buffer must be non-null");
}
if (count < 0) {
return util::Status(absl::StatusCode::kInvalidArgument,
"count cannot be negative");
}
if (count > dest_buffer->allocated_size()) {
return util::Status(absl::StatusCode::kInvalidArgument,
"buffer too small");
}
if (position < 0) {
return util::Status(absl::StatusCode::kInvalidArgument,
"position cannot be negative");
}
absl::ReaderMutexLock lock(&matching_mutex_);
if (matching_stream_ != nullptr) {
return matching_stream_->PRead(position, count, dest_buffer);
}
if (attempted_matching_) {
return Status(absl::StatusCode::kInvalidArgument,
"Did not find a decrypter matching the ciphertext stream.");
}
}
// Matching has not been attempted yet, so try it now.
absl::MutexLock lock(&matching_mutex_);
// Re-check that matching hasn't been attempted in the meantime.
if (matching_stream_ != nullptr) {
return matching_stream_->PRead(position, count, dest_buffer);
}
if (attempted_matching_) {
return Status(absl::StatusCode::kInvalidArgument,
"Did not find a decrypter matching the ciphertext stream.");
}
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 = absl::make_unique<SharedRandomAccessStream>(
ciphertext_source_.get());
auto decrypting_stream_result =
streaming_aead.NewDecryptingRandomAccessStream(
std::move(shared_ct), associated_data_);
if (decrypting_stream_result.ok()) {
auto status =
decrypting_stream_result.value()->PRead(position, count, dest_buffer);
if (status.ok() || status.code() == absl::StatusCode::kOutOfRange) {
// Found a match.
matching_stream_ = std::move(decrypting_stream_result.value());
return status;
}
}
// Not a match, try the next primitive.
}
return Status(absl::StatusCode::kInvalidArgument,
"Could not find a decrypter matching the ciphertext stream.");
}
StatusOr<int64_t> DecryptingRandomAccessStream::size() {
absl::ReaderMutexLock lock(&matching_mutex_);
if (matching_stream_ != nullptr) {
return matching_stream_->size();
}
// TODO(b/139722894): attempt matching here?
return Status(absl::StatusCode::kUnavailable, "no matching found yet");
}
} // namespace streamingaead
} // namespace tink
} // namespace crypto
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