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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/reporting/encryption/decryption.h"
#include <limits>
#include <memory>
#include <string>
#include <string_view>
#include <utility>
#include "base/containers/span.h"
#include "base/hash/hash.h"
#include "base/memory/ptr_util.h"
#include "base/rand_util.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "base/task/task_runner.h"
#include "base/task/thread_pool.h"
#include "base/types/expected.h"
#include "components/reporting/encryption/encryption.h"
#include "components/reporting/encryption/primitives.h"
#include "components/reporting/encryption/testing_primitives.h"
#include "components/reporting/util/status.h"
#include "components/reporting/util/statusor.h"
namespace reporting {
namespace test {
Decryptor::Handle::Handle(std::string_view shared_secret,
scoped_refptr<Decryptor> decryptor)
: shared_secret_(shared_secret), decryptor_(decryptor) {}
Decryptor::Handle::~Handle() = default;
void Decryptor::Handle::AddToRecord(std::string_view data,
base::OnceCallback<void(Status)> cb) {
// Add piece of data to the record.
record_.append(data);
std::move(cb).Run(Status::StatusOK());
}
void Decryptor::Handle::CloseRecord(
base::OnceCallback<void(StatusOr<std::string_view>)> cb) {
// Make sure the record self-destructs when returning from this method.
const auto self_destruct = base::WrapUnique(this);
// Produce symmetric key from shared secret using HKDF.
// Since the original keys were only used once, no salt and context is needed.
uint8_t out_symmetric_key[kKeySize];
if (!ProduceSymmetricKey(
reinterpret_cast<const uint8_t*>(shared_secret_.data()),
out_symmetric_key)) {
std::move(cb).Run(base::unexpected(
Status(error::INTERNAL, "Symmetric key extraction failed")));
return;
}
std::string decrypted;
PerformSymmetricDecryption(out_symmetric_key, record_, &decrypted);
record_.clear();
// Return decrypted record.
std::move(cb).Run(decrypted);
}
void Decryptor::OpenRecord(std::string_view shared_secret,
base::OnceCallback<void(StatusOr<Handle*>)> cb) {
std::move(cb).Run(new Handle(shared_secret, this));
}
StatusOr<std::string> Decryptor::DecryptSecret(
std::string_view private_key,
std::string_view peer_public_value) {
// Verify the keys.
if (private_key.size() != kKeySize) {
return base::unexpected(Status(
error::FAILED_PRECONDITION,
base::StrCat({"Private key size mismatch, expected=",
base::NumberToString(kKeySize),
" actual=", base::NumberToString(private_key.size())})));
}
if (peer_public_value.size() != kKeySize) {
return base::unexpected(
Status(error::FAILED_PRECONDITION,
base::StrCat({"Public key size mismatch, expected=",
base::NumberToString(kKeySize), " actual=",
base::NumberToString(peer_public_value.size())})));
}
// Compute shared secret.
uint8_t out_shared_value[kKeySize];
RestoreSharedSecret(
reinterpret_cast<const uint8_t*>(private_key.data()),
reinterpret_cast<const uint8_t*>(peer_public_value.data()),
out_shared_value);
return std::string(reinterpret_cast<const char*>(out_shared_value), kKeySize);
}
Decryptor::Decryptor()
: keys_sequenced_task_runner_(base::ThreadPool::CreateSequencedTaskRunner(
{base::TaskPriority::BEST_EFFORT, base::MayBlock()})) {
DETACH_FROM_SEQUENCE(keys_sequence_checker_);
}
Decryptor::~Decryptor() = default;
void Decryptor::RecordKeyPair(
std::string_view private_key,
std::string_view public_key,
base::OnceCallback<void(StatusOr<Encryptor::PublicKeyId>)> cb) {
// Schedule key recording on the sequenced task runner.
keys_sequenced_task_runner_->PostTask(
FROM_HERE,
base::BindOnce(
[](std::string public_key, KeyInfo key_info,
base::OnceCallback<void(StatusOr<Encryptor::PublicKeyId>)> cb,
scoped_refptr<Decryptor> decryptor) {
DCHECK_CALLED_ON_VALID_SEQUENCE(decryptor->keys_sequence_checker_);
StatusOr<Encryptor::PublicKeyId> result =
CreateUnknownErrorStatusOr();
if (key_info.private_key.size() != kKeySize) {
result = base::unexpected(Status(
error::FAILED_PRECONDITION,
base::StrCat(
{"Private key size mismatch, expected=",
base::NumberToString(kKeySize), " actual=",
base::NumberToString(key_info.private_key.size())})));
} else if (public_key.size() != kKeySize) {
result = base::unexpected(Status(
error::FAILED_PRECONDITION,
base::StrCat({"Public key size mismatch, expected=",
base::NumberToString(kKeySize), " actual=",
base::NumberToString(public_key.size())})));
} else {
// Assign a random number to be public key id for testing purposes
// only (in production it will be retrieved from the server as
// 'int32').
const Encryptor::PublicKeyId public_key_id = base::RandGenerator(
std::numeric_limits<Encryptor::PublicKeyId>::max());
if (!decryptor->keys_.emplace(public_key_id, key_info).second) {
result = base::unexpected(
Status(error::ALREADY_EXISTS,
base::StrCat({"Public key='", public_key,
"' already recorded"})));
} else {
result = public_key_id;
}
}
// Schedule response on a generic thread pool.
base::ThreadPool::PostTask(
FROM_HERE, base::BindOnce(
[](base::OnceCallback<void(
StatusOr<Encryptor::PublicKeyId>)> cb,
StatusOr<Encryptor::PublicKeyId> result) {
std::move(cb).Run(result);
},
std::move(cb), result));
},
std::string(public_key),
KeyInfo{.private_key = std::string(private_key),
.time_stamp = base::Time::Now()},
std::move(cb), base::WrapRefCounted(this)));
}
void Decryptor::RetrieveMatchingPrivateKey(
Encryptor::PublicKeyId public_key_id,
base::OnceCallback<void(StatusOr<std::string>)> cb) {
// Schedule key retrieval on the sequenced task runner.
keys_sequenced_task_runner_->PostTask(
FROM_HERE,
base::BindOnce(
[](Encryptor::PublicKeyId public_key_id,
base::OnceCallback<void(StatusOr<std::string>)> cb,
scoped_refptr<Decryptor> decryptor) {
DCHECK_CALLED_ON_VALID_SEQUENCE(decryptor->keys_sequence_checker_);
auto key_info_it = decryptor->keys_.find(public_key_id);
if (key_info_it != decryptor->keys_.end()) {
CHECK_EQ(key_info_it->second.private_key.size(),
static_cast<size_t>(kKeySize));
}
// Schedule response on a generic thread pool.
base::ThreadPool::PostTask(
FROM_HERE,
base::BindOnce(
[](base::OnceCallback<void(StatusOr<std::string>)> cb,
StatusOr<std::string> result) {
std::move(cb).Run(result);
},
std::move(cb),
key_info_it == decryptor->keys_.end()
? StatusOr<std::string>(base::unexpected(Status(
error::NOT_FOUND, "Matching key not found")))
: key_info_it->second.private_key));
},
public_key_id, std::move(cb), base::WrapRefCounted(this)));
}
StatusOr<scoped_refptr<Decryptor>> Decryptor::Create() {
return base::WrapRefCounted(new Decryptor());
}
} // namespace test
} // namespace reporting
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