sync/internal_api/public/sync_encryption_handler.h

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef SYNC_INTERNAL_API_PUBLIC_SYNC_ENCRYPTION_HANDLER_H_
   6 #define SYNC_INTERNAL_API_PUBLIC_SYNC_ENCRYPTION_HANDLER_H_
   7
   8 #include <string>
   9
  10 #include "base/time/time.h"
  11 #include "sync/base/sync_export.h"
  12 #include "sync/internal_api/public/base/model_type.h"
  13
  14 namespace sync_pb {
  15 class EncryptedData;
  16 }
  17
  18 namespace syncer {
  19
  20 class Cryptographer;
  21
  22 // Reasons due to which Cryptographer might require a passphrase.
  23 enum PassphraseRequiredReason {
  24   REASON_PASSPHRASE_NOT_REQUIRED = 0,  // Initial value.
  25   REASON_ENCRYPTION = 1,               // The cryptographer requires a
  26                                        // passphrase for its first attempt at
  27                                        // encryption. Happens only during
  28                                        // migration or upgrade.
  29   REASON_DECRYPTION = 2,               // The cryptographer requires a
  30                                        // passphrase for its first attempt at
  31                                        // decryption.
  32 };
  33
  34 // The different states for the encryption passphrase. These control if and how
  35 // the user should be prompted for a decryption passphrase.
  36 // Do not re-order or delete these entries; they are used in a UMA histogram.
  37 // Please edit SyncPassphraseType in histograms.xml if a value is added.
  38 enum PassphraseType {
  39   IMPLICIT_PASSPHRASE = 0,             // GAIA-based passphrase (deprecated).
  40   KEYSTORE_PASSPHRASE = 1,             // Keystore passphrase.
  41   FROZEN_IMPLICIT_PASSPHRASE = 2,      // Frozen GAIA passphrase.
  42   CUSTOM_PASSPHRASE = 3,               // User-provided passphrase.
  43   PASSPHRASE_TYPE_SIZE,                // The size of this enum; keep last.
  44 };
  45
  46 // Enum used to distinguish which bootstrap encryption token is being updated.
  47 enum BootstrapTokenType {
  48   PASSPHRASE_BOOTSTRAP_TOKEN,
  49   KEYSTORE_BOOTSTRAP_TOKEN
  50 };
  51
  52 // Sync's encryption handler. Handles tracking encrypted types, ensuring the
  53 // cryptographer encrypts with the proper key and has the most recent keybag,
  54 // and keeps the nigori node up to date.
  55 // Implementations of this class must be assumed to be non-thread-safe. All
  56 // methods must be invoked on the sync thread.
  57 class SYNC_EXPORT SyncEncryptionHandler {
  58  public:
  59   // All Observer methods are done synchronously from within a transaction and
  60   // on the sync thread.
  61   class SYNC_EXPORT Observer {
  62    public:
  63     Observer();
  64
  65     // Called when user interaction is required to obtain a valid passphrase.
  66     // - If the passphrase is required for encryption, |reason| will be
  67     //   REASON_ENCRYPTION.
  68     // - If the passphrase is required for the decryption of data that has
  69     //   already been encrypted, |reason| will be REASON_DECRYPTION.
  70     // - If the passphrase is required because decryption failed, and a new
  71     //   passphrase is required, |reason| will be REASON_SET_PASSPHRASE_FAILED.
  72     //
  73     // |pending_keys| is a copy of the cryptographer's pending keys, that may be
  74     // cached by the frontend for subsequent use by the UI.
  75     virtual void OnPassphraseRequired(
  76         PassphraseRequiredReason reason,
  77         const sync_pb::EncryptedData& pending_keys) = 0;
  78     // Called when the passphrase provided by the user has been accepted and is
  79     // now used to encrypt sync data.
  80
  81     virtual void OnPassphraseAccepted() = 0;
  82     // |bootstrap_token| is an opaque base64 encoded representation of the key
  83     // generated by the current passphrase, and is provided to the observer for
  84     // persistence purposes and use in a future initialization of sync (e.g.
  85     // after restart). The boostrap token will always be derived from the most
  86     // recent GAIA password (for accounts with implicit passphrases), even if
  87     // the data is still encrypted with an older GAIA password. For accounts
  88     // with explicit passphrases, it will be the most recently seen custom
  89     // passphrase.
  90     virtual void OnBootstrapTokenUpdated(
  91         const std::string& bootstrap_token,
  92         BootstrapTokenType type) = 0;
  93
  94     // Called when the set of encrypted types or the encrypt
  95     // everything flag has been changed.  Note that encryption isn't
  96     // complete until the OnEncryptionComplete() notification has been
  97     // sent (see below).
  98     //
  99     // |encrypted_types| will always be a superset of
 100     // Cryptographer::SensitiveTypes().  If |encrypt_everything| is
 101     // true, |encrypted_types| will be the set of all known types.
 102     //
 103     // Until this function is called, observers can assume that the
 104     // set of encrypted types is Cryptographer::SensitiveTypes() and
 105     // that the encrypt everything flag is false.
 106     virtual void OnEncryptedTypesChanged(
 107         ModelTypeSet encrypted_types,
 108         bool encrypt_everything) = 0;
 109
 110     // Called after we finish encrypting the current set of encrypted
 111     // types.
 112     virtual void OnEncryptionComplete() = 0;
 113
 114     // The cryptographer has been updated. Listeners should check that their
 115     // own state matches the cryptographer.
 116     // Used primarily for debugging.
 117     virtual void OnCryptographerStateChanged(Cryptographer* cryptographer) = 0;
 118
 119     // The passphrase type has changed. |type| is the new type,
 120     // |passphrase_time| is the time the passphrase was set (unset if |type|
 121     // is KEYSTORE_PASSPHRASE or the passphrase was set before we started
 122     // recording the time).
 123     virtual void OnPassphraseTypeChanged(PassphraseType type,
 124                                          base::Time passphrase_time) = 0;
 125
 126    protected:
 127     virtual ~Observer();
 128   };
 129
 130   SyncEncryptionHandler();
 131   virtual ~SyncEncryptionHandler();
 132
 133   // Add/Remove SyncEncryptionHandler::Observers.
 134   virtual void AddObserver(Observer* observer) = 0;
 135   virtual void RemoveObserver(Observer* observer) = 0;
 136
 137   // Reads the nigori node, updates internal state as needed, and, if an
 138   // empty/stale nigori node is detected, overwrites the existing
 139   // nigori node. Upon completion, if the cryptographer is still ready
 140   // attempts to re-encrypt all sync data.
 141   // Note: This method is expensive (it iterates through all encrypted types),
 142   // so should only be used sparingly (e.g. on startup).
 143   virtual void Init() = 0;
 144
 145   // Attempts to re-encrypt encrypted data types using the passphrase provided.
 146   // Notifies observers of the result of the operation via OnPassphraseAccepted
 147   // or OnPassphraseRequired, updates the nigori node, and does re-encryption as
 148   // appropriate. If an explicit password has been set previously, we drop
 149   // subsequent requests to set a passphrase. If the cryptographer has pending
 150   // keys, and a new implicit passphrase is provided, we try decrypting the
 151   // pending keys with it, and if that fails, we cache the passphrase for
 152   // re-encryption once the pending keys are decrypted.
 153   virtual void SetEncryptionPassphrase(const std::string& passphrase,
 154                                        bool is_explicit) = 0;
 155
 156   // Provides a passphrase for decrypting the user's existing sync data.
 157   // Notifies observers of the result of the operation via OnPassphraseAccepted
 158   // or OnPassphraseRequired, updates the nigori node, and does re-encryption as
 159   // appropriate if there is a previously cached encryption passphrase. It is an
 160   // error to call this when we don't have pending keys.
 161   virtual void SetDecryptionPassphrase(const std::string& passphrase) = 0;
 162
 163   // Enables encryption of all datatypes.
 164   virtual void EnableEncryptEverything() = 0;
 165
 166   // Whether encryption of all datatypes is enabled. If false, only sensitive
 167   // types are encrypted.
 168   virtual bool EncryptEverythingEnabled() const = 0;
 169
 170   // Returns the current state of the passphrase needed to decrypt the
 171   // bag of encryption keys in the nigori node.
 172   virtual PassphraseType GetPassphraseType() const = 0;
 173
 174   // The set of types that are always encrypted.
 175   static ModelTypeSet SensitiveTypes();
 176 };
 177
 178 }  // namespace syncer
 179
 180 #endif  // SYNC_INTERNAL_API_PUBLIC_SYNC_ENCRYPTION_HANDLER_H_