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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.
#ifndef COMPONENTS_CRYPTAUTH_DEVICE_TO_DEVICE_INITIATOR_OPERATIONS_H_
#define COMPONENTS_CRYPTAUTH_DEVICE_TO_DEVICE_INITIATOR_OPERATIONS_H_
#include <string>
#include "base/callback_forward.h"
#include "base/macros.h"
namespace cryptauth {
class SecureMessageDelegate;
// Utility class containing operations in the DeviceToDevice protocol that the
// initiator needs to perform. For Smart Lock, in which a phone unlocks a
// laptop, the initiator is laptop.
//
// All operations are asynchronous because we use the SecureMessageDelegate for
// crypto operations, whose implementation may be asynchronous.
//
// In the DeviceToDevice protocol, the initiator needs to send two messages to
// the responder and parse one message from the responder:
// 1. Send [Hello] Message
// This message contains a public key that the initiator generates for the
// current session. This message is signed by the long term symmetric key.
// 2. Parse [Responder Auth] Message
// The responder parses [Hello] and sends this message, which contains the
// responder's session public key. This message also contains sufficient
// information for the initiator to authenticate the responder.
// 3. Send [Initiator Auth] Message
// After receiving the responder's session public key, the initiator crafts
// and sends this message so the responder can authenticate the initiator.
class DeviceToDeviceInitiatorOperations {
public:
// Callback for operations that create a message. Invoked with the serialized
// SecureMessage upon success or the empty string upon failure.
typedef base::Callback<void(const std::string&)> MessageCallback;
// Callback for ValidateResponderAuthMessage. The first argument will be
// called with the validation outcome. If validation succeeded, then the
// second argument will contain the session symmetric key derived from the
// [Responder Auth] message.
typedef base::Callback<void(bool, const std::string&)>
ValidateResponderAuthCallback;
// Creates the [Hello] message, which is the first message that is sent:
// |session_public_key|: This session public key will be stored in plaintext
// (but signed) so the responder can parse it.
// |persistent_symmetric_key|: The long-term symmetric key that is shared by
// the initiator and responder.
// |secure_message_delegate|: Delegate for SecureMessage operations. This
// instance is not owned, and must live until after |callback| is invoked.
// |callback|: Invoked upon operation completion with the serialized message
// or an empty string.
static void CreateHelloMessage(
const std::string& session_public_key,
const std::string& persistent_symmetric_key,
SecureMessageDelegate* secure_message_delegate,
const MessageCallback& callback);
// Validates that the [Responder Auth] message, received from the responder,
// is properly signed and encrypted.
// |responder_auth_message|: The bytes of the [Responder Auth] message to
// validate.
// |persistent_responder_public_key|: The long-term public key possessed by
// the responder device.
// |persistent_symmetric_key|: The long-term symmetric key that is shared by
// the initiator and responder.
// |session_private_key|: The session private key is used in an Diffie-Helmann
// key exchange once the responder public key is extracted. The derived
// session symmetric key is used in the validation process.
// |hello_message|: The initial [Hello] message that was sent, which is used
// in the signature calculation.
// |secure_message_delegate|: Delegate for SecureMessage operations. This
// instance is not owned, and must live until after |callback| is invoked.
// |callback|: Invoked upon operation completion with whether
// |responder_auth_message| is validated successfully.
static void ValidateResponderAuthMessage(
const std::string& responder_auth_message,
const std::string& persistent_responder_public_key,
const std::string& persistent_symmetric_key,
const std::string& session_private_key,
const std::string& hello_message,
SecureMessageDelegate* secure_message_delegate,
const ValidateResponderAuthCallback& callback);
// Creates the [Initiator Auth] message, which allows the responder to
// authenticate the initiator:
// |persistent_symmetric_key|: The long-term symmetric key that is shared by
// the initiator and responder.
// |responder_auth_message|: The [Responder Auth] message sent previously to
// the responder. These bytes are used in the signature calculation.
// |secure_message_delegate|: Delegate for SecureMessage operations. This
// instance is not owned, and must live until after |callback| is invoked.
// |callback|: Invoked upon operation completion with the serialized message
// or an empty string.
static void CreateInitiatorAuthMessage(
const std::string& session_symmetric_key,
const std::string& persistent_symmetric_key,
const std::string& responder_auth_message,
SecureMessageDelegate* secure_message_delegate,
const MessageCallback& callback);
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(DeviceToDeviceInitiatorOperations);
};
} // cryptauth
#endif // COMPONENTS_CRYPTAUTH_DEVICE_TO_DEVICE_INITIATOR_OPERATIONS_H_
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