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// Copyright 2014 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 CHROME_BROWSER_CHROMEOS_LOGIN_EASY_UNLOCK_EASY_UNLOCK_TPM_KEY_MANAGER_H_
#define CHROME_BROWSER_CHROMEOS_LOGIN_EASY_UNLOCK_EASY_UNLOCK_TPM_KEY_MANAGER_H_
#include <stddef.h>
#include <string>
#include <vector>
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "components/account_id/account_id.h"
#include "components/keyed_service/core/keyed_service.h"
#include "crypto/scoped_nss_types.h"
class PrefRegistrySimple;
class PrefService;
namespace chromeos {
// Manages per user RSA keys stored in system TPM slot used in easy signin
// protocol. The keys are used to sign a nonce exchanged during signin.
class EasyUnlockTpmKeyManager : public KeyedService {
public:
// Registers local state prefs used to store public RSA keys per user.
static void RegisterLocalStatePrefs(PrefRegistrySimple* registry);
// Clears local state for user. Should be called when a user is removed.
static void ResetLocalStateForUser(const AccountId& account_id);
// |account_id|: Id for the user associated with the service. Empty for
// sign-in service.
// |username_hash|: Username hash for the user associated with the service.
// Empty for sign-in service.
// |local_state|: The local state prefs.
EasyUnlockTpmKeyManager(const AccountId& account_id,
const std::string& username_hash,
PrefService* local_state);
~EasyUnlockTpmKeyManager() override;
// Checks if the RSA public key is set in the local state. If not, creates
// one. If the key presence can be confirmed, immediately returns true and
// |callback| never gets called, otherwise returns false (callback is called
// when the key presence is confirmed).
// Must not be called for signin profile.
// |check_private_key|: If public RSA key is set in the local state, whether
// the method should confirm that the private key is present in the system
// slot. If the private key cannot be found, a new key pair will be
// created for the user.
// Note: Checking TPM for the private key is more expensive than only
// checking local state, so setting this to |false| should be preferable.
// Generally, if public key is set in local state, the private key should
// be present in the system TPM slot. This is used to make sure that easy
// signin does not remain permanently broken if something goes wrong.
// |callback|: If the method cannot return immediately, called when the key
// pair presence is confirmed (or a key pair for the user is created).
bool PrepareTpmKey(bool check_private_key, const base::Closure& callback);
// If called, posts a delayed task that cancels |PrepareTpmKey| and all other
// started timeouts in case getting system slot takes more than |timeout_ms|.
// In the case getting system slot times out, |PrepareTpmKey| callback will
// be called with an empty public key.
// Must be called after |PrepareTpmKey| to have the intended effect.
bool StartGetSystemSlotTimeoutMs(size_t timeout_ms);
// Gets the public RSA key for user. The key is retrieved from local state.
std::string GetPublicTpmKey(const AccountId& account_id);
// Signs |data| using private RSA key associated with |user_id| stored in TPM
// system slot.
void SignUsingTpmKey(
const AccountId& account_id,
const std::string& data,
const base::Callback<void(const std::string& data)> callback);
bool StartedCreatingTpmKeys() const;
private:
enum CreateTpmKeyState {
CREATE_TPM_KEY_NOT_STARTED,
CREATE_TPM_KEY_WAITING_FOR_USER_SLOT,
CREATE_TPM_KEY_WAITING_FOR_SYSTEM_SLOT,
CREATE_TPM_KEY_GOT_SYSTEM_SLOT,
CREATE_TPM_KEY_DONE
};
// Utility method for setting public key values in local state.
// Note that the keys are saved base64 encoded.
void SetKeyInLocalState(const AccountId& account_id,
const std::string& value);
// Called when TPM system slot is initialized and ready to be used.
// It creates RSA key pair for the user in the system slot.
// When the key pair is created, |OnTpmKeyCreated| will be called with the
// created public key.
// The key will not be created if |public_key| is non-empty and the associated
// private key can be found in the slot. Instead |OnTpmKeyCreated| will be
// called with |public_key|.
void CreateKeyInSystemSlot(const std::string& public_key,
crypto::ScopedPK11Slot system_slot);
// Called when user TPM token initialization is done. After this happens,
// |this| may proceed with creating a user-specific TPM key for easy sign-in.
// Note that this is done solely to ensure user TPM initialization, which is
// done on IO thread, is not blocked by creating TPM keys in system slot.
void OnUserTPMInitialized(const std::string& public_key);
// Called when TPM system slot is initialized and ready to be used.
// It schedules data signing operation on a worker thread. The data is signed
// by a private key stored in |system_slot| and identified by |public_key|
// (a private key that is part of the same RSA key pair as |public_key|).
// Once data is signed |callback| is called with the signed data.
void SignDataWithSystemSlot(
const std::string& public_key,
const std::string& data,
const base::Callback<void(const std::string& data)> callback,
crypto::ScopedPK11Slot system_slot);
// Called when a RSA key pair is created for a user in TPM system slot.
// It saves the pulic key in the local state and runs queued up
// |PrepareTpmKey| callbacks.
void OnTpmKeyCreated(const std::string& public_key);
// Called when data signing requested in |SignUsingTpmKey| is done.
// It runs |callback| with the created |signature|. On error the callback will
// be run with an empty string.
void OnDataSigned(const base::Callback<void(const std::string&)>& callback,
const std::string& signature);
const AccountId account_id_;
std::string username_hash_;
PrefService* local_state_;
// The current TPM key creation state. If key creation is in progress,
// callbacks for further |PrepareTpmKey| will be queued up and run when the
// key is created. All queued callbacks will be run with the same key value.
CreateTpmKeyState create_tpm_key_state_;
// Queued up |PrepareTpmKey| callbacks.
std::vector<base::Closure> prepare_tpm_key_callbacks_;
base::WeakPtrFactory<EasyUnlockTpmKeyManager> get_tpm_slot_weak_ptr_factory_;
base::WeakPtrFactory<EasyUnlockTpmKeyManager> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(EasyUnlockTpmKeyManager);
};
} // namespace chromeos
#endif // CHROME_BROWSER_CHROMEOS_LOGIN_EASY_UNLOCK_EASY_UNLOCK_TPM_KEY_MANAGER_H_