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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.
#ifndef COMPONENTS_REPORTING_ENCRYPTION_DECRYPTION_H_
#define COMPONENTS_REPORTING_ENCRYPTION_DECRYPTION_H_
#include <string>
#include <string_view>
#include "base/containers/flat_map.h"
#include "base/functional/callback.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/task/sequenced_task_runner.h"
#include "base/threading/thread.h"
#include "components/reporting/encryption/encryption.h"
#include "components/reporting/util/status.h"
#include "components/reporting/util/statusor.h"
namespace reporting {
namespace test {
// Full implementation of Decryptor, intended for use in tests and potentially
// in reporting server (wrapped in a Java class).
//
// Curve25519 decryption of the symmetric key with asymmetric private key.
// ChaCha20_Poly1305 decryption and verification of a record in place with
// symmetric key.
//
// Instantiated by an implementation-specific factory:
// StatusOr<scoped_refptr<Decryptor>> Create();
class Decryptor : public base::RefCountedThreadSafe<Decryptor> {
public:
// Decryption record handle, which is created by |OpenRecord| and can accept
// pieces of data to be decrypted as one record by calling |AddToRecord|
// multiple times. Resulting decrypted record is available once |CloseRecord|
// is called.
class Handle {
public:
Handle(std::string_view shared_secret, scoped_refptr<Decryptor> decryptor);
Handle(const Handle& other) = delete;
Handle& operator=(const Handle& other) = delete;
~Handle();
// Adds piece of encrypted data to the record.
void AddToRecord(std::string_view data,
base::OnceCallback<void(Status)> cb);
// Closes and attempts to decrypt the record. Hands over the decrypted data
// to be processed by the server (or Status if unsuccessful). Accesses key
// store to attempt all private keys that are considered to be valid,
// starting with the one that matches the hash. Self-destructs after the
// callback.
void CloseRecord(base::OnceCallback<void(StatusOr<std::string_view>)> cb);
private:
// Shared secret based on which symmetric key is produced.
const std::string shared_secret_;
// Accumulated data to decrypt.
std::string record_;
scoped_refptr<Decryptor> decryptor_;
};
// Factory method to instantiate the Decryptor.
static StatusOr<scoped_refptr<Decryptor>> Create();
// Factory method creates a new record to collect data and decrypt them with
// the given encrypted key. Hands the handle raw pointer over to the callback,
// or error status.
void OpenRecord(std::string_view encrypted_key,
base::OnceCallback<void(StatusOr<Handle*>)> cb);
// Recreates shared secret from local private key and peer public value and
// returns it or error status.
StatusOr<std::string> DecryptSecret(std::string_view public_key,
std::string_view peer_public_value);
// Records a key pair (stores only private key).
// Executes on a sequenced thread, returns key id or error with callback.
void RecordKeyPair(
std::string_view private_key,
std::string_view public_key,
base::OnceCallback<void(StatusOr<Encryptor::PublicKeyId>)> cb);
// Retrieves private key matching the public key hash.
// Executes on a sequenced thread, returns with callback.
void RetrieveMatchingPrivateKey(
Encryptor::PublicKeyId public_key_id,
base::OnceCallback<void(StatusOr<std::string>)> cb);
private:
friend base::RefCountedThreadSafe<Decryptor>;
Decryptor();
~Decryptor();
// Map of hash(public_key)->{private key, time stamp}
// Private key is located by the hash of a public key, sent together with the
// encrypted record. Keys older than pre-defined threshold are discarded.
// Time stamp allows to drop outdated keys (not implemented yet).
struct KeyInfo {
std::string private_key;
base::Time time_stamp;
};
base::flat_map<Encryptor::PublicKeyId, KeyInfo> keys_;
// Sequential task runner for all keys_ activities:
// recording, lookup, purge.
scoped_refptr<base::SequencedTaskRunner> keys_sequenced_task_runner_;
SEQUENCE_CHECKER(keys_sequence_checker_);
};
} // namespace test
} // namespace reporting
#endif // COMPONENTS_REPORTING_ENCRYPTION_DECRYPTION_H_
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