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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/proximity_auth/device_to_device_authenticator.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "components/proximity_auth/connection.h"
#include "components/proximity_auth/cryptauth/secure_message_delegate.h"
#include "components/proximity_auth/device_to_device_initiator_operations.h"
#include "components/proximity_auth/device_to_device_secure_context.h"
#include "components/proximity_auth/logging/logging.h"
#include "components/proximity_auth/secure_context.h"
#include "components/proximity_auth/wire_message.h"
namespace proximity_auth {
namespace {
// The time to wait in seconds for the remote device to send its
// [Responder Auth] message. If we do not get the message in this time, then
// authentication will fail.
const int kResponderAuthTimeoutSeconds = 5;
// The prefix of the permit id sent to the remote device. The permit id
// is used by the remote device to find the credentials of the local device.
const char kPermitIdPrefix[] = "permit://google.com/easyunlock/v1/";
} // namespace
DeviceToDeviceAuthenticator::DeviceToDeviceAuthenticator(
Connection* connection,
const std::string& account_id,
scoped_ptr<SecureMessageDelegate> secure_message_delegate)
: connection_(connection),
account_id_(account_id),
secure_message_delegate_(secure_message_delegate.Pass()),
state_(State::NOT_STARTED),
weak_ptr_factory_(this) {
DCHECK(connection_);
}
DeviceToDeviceAuthenticator::~DeviceToDeviceAuthenticator() {
connection_->RemoveObserver(this);
}
void DeviceToDeviceAuthenticator::Authenticate(
const AuthenticationCallback& callback) {
if (state_ != State::NOT_STARTED) {
PA_LOG(ERROR)
<< "Authenticator was already used. Do not reuse this instance!";
callback.Run(Result::FAILURE, nullptr);
return;
}
callback_ = callback;
if (!connection_->IsConnected()) {
Fail("Not connected to remote device", Result::DISCONNECTED);
return;
}
connection_->AddObserver(this);
// Generate a key-pair for this individual session.
state_ = State::GENERATING_SESSION_KEYS;
secure_message_delegate_->GenerateKeyPair(
base::Bind(&DeviceToDeviceAuthenticator::OnKeyPairGenerated,
weak_ptr_factory_.GetWeakPtr()));
}
void DeviceToDeviceAuthenticator::OnKeyPairGenerated(
const std::string& public_key,
const std::string& private_key) {
DCHECK(state_ == State::GENERATING_SESSION_KEYS);
if (public_key.empty() || private_key.empty()) {
Fail("Failed to generate session keys");
return;
}
local_session_private_key_ = private_key;
// Create the [Hello] message to send to the remote device.
state_ = State::SENDING_HELLO;
DeviceToDeviceInitiatorOperations::CreateHelloMessage(
public_key, connection_->remote_device().persistent_symmetric_key,
secure_message_delegate_.get(),
base::Bind(&DeviceToDeviceAuthenticator::OnHelloMessageCreated,
weak_ptr_factory_.GetWeakPtr()));
}
scoped_ptr<base::Timer> DeviceToDeviceAuthenticator::CreateTimer() {
return make_scoped_ptr(new base::OneShotTimer<DeviceToDeviceAuthenticator>());
}
void DeviceToDeviceAuthenticator::OnHelloMessageCreated(
const std::string& message) {
DCHECK(state_ == State::SENDING_HELLO);
if (message.empty()) {
Fail("Failed to create [Hello]");
return;
}
// Add a timeout for receiving the [Responder Auth] message as a guard.
timer_ = CreateTimer();
timer_->Start(
FROM_HERE, base::TimeDelta::FromSeconds(kResponderAuthTimeoutSeconds),
base::Bind(&DeviceToDeviceAuthenticator::OnResponderAuthTimedOut,
weak_ptr_factory_.GetWeakPtr()));
// Send the [Hello] message to the remote device.
state_ = State::SENT_HELLO;
hello_message_ = message;
std::string permit_id = kPermitIdPrefix + account_id_;
connection_->SendMessage(
make_scoped_ptr(new WireMessage(hello_message_, permit_id)));
}
void DeviceToDeviceAuthenticator::OnResponderAuthTimedOut() {
DCHECK(state_ == State::SENT_HELLO);
Fail("Timed out waiting for [Responder Auth]");
}
void DeviceToDeviceAuthenticator::OnResponderAuthValidated(
bool validated,
const std::string& session_symmetric_key) {
if (!validated) {
Fail("Unable to validated [Responder Auth]");
return;
}
PA_LOG(INFO) << "Successfully validated [Responder Auth]! "
<< "Sending [Initiator Auth]...";
state_ = State::VALIDATED_RESPONDER_AUTH;
session_symmetric_key_ = session_symmetric_key;
// Create the [Initiator Auth] message to send to the remote device.
DeviceToDeviceInitiatorOperations::CreateInitiatorAuthMessage(
session_symmetric_key,
connection_->remote_device().persistent_symmetric_key,
responder_auth_message_, secure_message_delegate_.get(),
base::Bind(&DeviceToDeviceAuthenticator::OnInitiatorAuthCreated,
weak_ptr_factory_.GetWeakPtr()));
}
void DeviceToDeviceAuthenticator::OnInitiatorAuthCreated(
const std::string& message) {
DCHECK(state_ == State::VALIDATED_RESPONDER_AUTH);
if (message.empty()) {
Fail("Failed to create [Initiator Auth]");
return;
}
state_ = State::SENT_INITIATOR_AUTH;
connection_->SendMessage(make_scoped_ptr(new WireMessage(message)));
}
void DeviceToDeviceAuthenticator::Fail(const std::string& error_message) {
Fail(error_message, Result::FAILURE);
}
void DeviceToDeviceAuthenticator::Fail(const std::string& error_message,
Result result) {
DCHECK(result != Result::SUCCESS);
PA_LOG(WARNING) << "Authentication failed: " << error_message;
state_ = State::AUTHENTICATION_FAILURE;
weak_ptr_factory_.InvalidateWeakPtrs();
connection_->RemoveObserver(this);
timer_.reset();
callback_.Run(result, nullptr);
}
void DeviceToDeviceAuthenticator::Succeed() {
DCHECK(state_ == State::SENT_INITIATOR_AUTH);
DCHECK(!session_symmetric_key_.empty());
PA_LOG(INFO) << "Authentication succeeded!";
state_ = State::AUTHENTICATION_SUCCESS;
connection_->RemoveObserver(this);
callback_.Run(
Result::SUCCESS,
make_scoped_ptr(new DeviceToDeviceSecureContext(
secure_message_delegate_.Pass(), session_symmetric_key_,
responder_auth_message_, SecureContext::PROTOCOL_VERSION_THREE_ONE)));
}
void DeviceToDeviceAuthenticator::OnConnectionStatusChanged(
Connection* connection,
Connection::Status old_status,
Connection::Status new_status) {
// We do not expect the connection to drop during authentication.
if (new_status == Connection::DISCONNECTED) {
Fail("Disconnected while authentication is in progress",
Result::DISCONNECTED);
}
}
void DeviceToDeviceAuthenticator::OnMessageReceived(
const Connection& connection,
const WireMessage& message) {
if (state_ == State::SENT_HELLO) {
PA_LOG(INFO) << "Received [Responder Auth] message, payload_size="
<< message.payload().size();
state_ = State::RECEIVED_RESPONDER_AUTH;
timer_.reset();
responder_auth_message_ = message.payload();
// Attempt to validate the [Responder Auth] message received from the remote
// device.
std::string responder_public_key = connection.remote_device().public_key;
DeviceToDeviceInitiatorOperations::ValidateResponderAuthMessage(
responder_auth_message_, responder_public_key,
connection_->remote_device().persistent_symmetric_key,
local_session_private_key_, hello_message_,
secure_message_delegate_.get(),
base::Bind(&DeviceToDeviceAuthenticator::OnResponderAuthValidated,
weak_ptr_factory_.GetWeakPtr()));
} else {
Fail("Unexpected message received");
}
}
void DeviceToDeviceAuthenticator::OnSendCompleted(const Connection& connection,
const WireMessage& message,
bool success) {
if (state_ == State::SENT_INITIATOR_AUTH) {
if (success)
Succeed();
else
Fail("Failed to send [Initiator Auth]");
} else if (!success && state_ == State::SENT_HELLO) {
DCHECK(message.payload() == hello_message_);
Fail("Failed to send [Hello]");
}
}
} // namespace proximity_auth
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