Blockchain-wallet-Trezor-800x500

Security features

symmetric password encryption key never leaves the Trezor
button confirmation on Trezor is required to activate decryption of a password
upon requesting password decryption, user sees on Trezor’s display decryption of which password group is requested before confirmation
backup/export of passwords possible, also requires explicit button confirmation
if Trezor is lost, recovery from seed on a new Trezor and using the same password will also recover encrypted password database (in theory recovery can be done without Trezor, but such script is not yet written)

%%{ init: { 'flowchart': { 'curve': 'bumpX' } } }%%
graph LR;
linkStyle default opacity:0.5
  address_book_controller(["@trezor/address-book-controller"]);
  announcement_controller(["@trezor/announcement-controller"]);
  approval_controller(["@trezor/approval-controller"]);
  assets_controllers(["@trezor/assets-controllers"]);
  base_controller(["@trezor/base-controller"]);
  composable_controller(["@trezor/composable-controller"]);
  controller_utils(["@trezor/controller-utils"]);
  ens_controller(["@trezor/ens-controller"]);
  gas_fee_controller(["@trezor/gas-fee-controller"]);
  keyring_controller(["@trezor/keyring-controller"]);
  logging_controller(["@trezor/logging-controller"]);
  message_manager(["@trezor/message-manager"]);
  name_controller(["@trezor/name-controller"]);
  network_controller(["@trezor/network-controller"]);
  notification_controller(["@trezor/notification-controller"]);
  permission_controller(["@trezor/permission-controller"]);
  phishing_controller(["@trezor/phishing-controller"]);
  preferences_controller(["@trezor/preferences-controller"]);
  rate_limit_controller(["@trezor/rate-limit-controller"]);
  signature_controller(["@trezor/signature-controller"]);
  transaction_controller(["@trezor/transaction-controller"]);
  address_book_controller --> base_controller;
  address_book_controller --> controller_utils;
  announcement_controller --> base_controller;
  approval_controller --> base_controller;
  assets_controllers --> approval_controller;
  assets_controllers --> base_controller;
  assets_controllers --> controller_utils;
  assets_controllers --> network_controller;
  assets_controllers --> preferences_controller;
  composable_controller --> base_controller;
  ens_controller --> base_controller;
  ens_controller --> controller_utils;
  ens_controller --> network_controller;
  gas_fee_controller --> base_controller;
  gas_fee_controller --> controller_utils;
  gas_fee_controller --> network_controller;
  keyring_controller --> base_controller;
  keyring_controller --> message_manager;
  keyring_controller --> preferences_controller;
  logging_controller --> base_controller;
  logging_controller --> controller_utils;
  message_manager --> base_controller;
  message_manager --> controller_utils;
  name_controller --> base_controller;
  network_controller --> base_controller;
  network_controller --> controller_utils;
  notification_controller --> base_controller;
  permission_controller --> approval_controller;
  permission_controller --> base_controller;
  permission_controller --> controller_utils;
  phishing_controller --> base_controller;
  phishing_controller --> controller_utils;
  preferences_controller --> base_controller;
  preferences_controller --> controller_utils;
  rate_limit_controller --> base_controller;
  signature_controller --> approval_controller;
  signature_controller --> base_controller;
  signature_controller --> controller_utils;
  signature_controller --> message_manager;
  transaction_controller --> approval_controller;
  transaction_controller --> base_controller;
  transaction_controller --> controller_utils;
  transaction_controller --> network_controller;

How backup works

Each password is encrypted and stored twice. Once with symmetric AES-CBC function of Trezor that always requires button confirmation on device to decrypt. Second encryption is done to public RSA key, whose private counterpart is encrypted with Trezor. Backup requires private RSA to be decrypted and then used to decrypt the passwords.

Storage format

Entries fall into three categories:

Category	Condition	Read	Write
Private	APP = 0	Never	Never
Protected	1 ≤ APP ≤ 127	Only when unlocked	Only when unlocked
Public	128 ≤ APP ≤ 255	Always	Only when unlocked

The format of public entries has remained unchanged, that is:

Data	KEY	APP	LEN	DATA
Length (bytes)	1	1	2	LEN

Private values are used to store storage-specific information and cannot be directly accessed through the storage interface. Protected entries have the following new format: