| // Copyright 2020, The Android Open Source Project |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| use crate::{ |
| boot_level_keys::{get_level_zero_key, BootLevelKeyCache}, |
| database::BlobMetaData, |
| database::BlobMetaEntry, |
| database::EncryptedBy, |
| database::KeyEntry, |
| database::KeyType, |
| database::{KeyIdGuard, KeyMetaData, KeyMetaEntry, KeystoreDB}, |
| ec_crypto::ECDHPrivateKey, |
| enforcements::Enforcements, |
| error::Error, |
| error::ResponseCode, |
| key_parameter::{KeyParameter, KeyParameterValue}, |
| legacy_blob::LegacyBlobLoader, |
| legacy_migrator::LegacyMigrator, |
| raw_device::KeyMintDevice, |
| try_insert::TryInsert, |
| utils::watchdog as wd, |
| }; |
| use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{ |
| Algorithm::Algorithm, BlockMode::BlockMode, HardwareAuthToken::HardwareAuthToken, |
| HardwareAuthenticatorType::HardwareAuthenticatorType, KeyFormat::KeyFormat, |
| KeyParameter::KeyParameter as KmKeyParameter, KeyPurpose::KeyPurpose, PaddingMode::PaddingMode, |
| SecurityLevel::SecurityLevel, |
| }; |
| use android_system_keystore2::aidl::android::system::keystore2::{ |
| Domain::Domain, KeyDescriptor::KeyDescriptor, |
| }; |
| use anyhow::{Context, Result}; |
| use keystore2_crypto::{ |
| aes_gcm_decrypt, aes_gcm_encrypt, generate_aes256_key, generate_salt, Password, ZVec, |
| AES_256_KEY_LENGTH, |
| }; |
| use keystore2_system_property::PropertyWatcher; |
| use std::{ |
| collections::HashMap, |
| sync::Arc, |
| sync::{Mutex, Weak}, |
| }; |
| use std::{convert::TryFrom, ops::Deref}; |
| |
| const MAX_MAX_BOOT_LEVEL: usize = 1_000_000_000; |
| /// Allow up to 15 seconds between the user unlocking using a biometric, and the auth |
| /// token being used to unlock in [`SuperKeyManager::try_unlock_user_with_biometric`]. |
| /// This seems short enough for security purposes, while long enough that even the |
| /// very slowest device will present the auth token in time. |
| const BIOMETRIC_AUTH_TIMEOUT_S: i32 = 15; // seconds |
| |
| type UserId = u32; |
| |
| /// Encryption algorithm used by a particular type of superencryption key |
| #[derive(Debug, Clone, Copy, PartialEq, Eq)] |
| pub enum SuperEncryptionAlgorithm { |
| /// Symmetric encryption with AES-256-GCM |
| Aes256Gcm, |
| /// Public-key encryption with ECDH P-256 |
| EcdhP256, |
| } |
| |
| /// A particular user may have several superencryption keys in the database, each for a |
| /// different purpose, distinguished by alias. Each is associated with a static |
| /// constant of this type. |
| pub struct SuperKeyType { |
| /// Alias used to look the key up in the `persistent.keyentry` table. |
| pub alias: &'static str, |
| /// Encryption algorithm |
| pub algorithm: SuperEncryptionAlgorithm, |
| } |
| |
| /// Key used for LskfLocked keys; the corresponding superencryption key is loaded in memory |
| /// when the user first unlocks, and remains in memory until the device reboots. |
| pub const USER_SUPER_KEY: SuperKeyType = |
| SuperKeyType { alias: "USER_SUPER_KEY", algorithm: SuperEncryptionAlgorithm::Aes256Gcm }; |
| /// Key used for ScreenLockBound keys; the corresponding superencryption key is loaded in memory |
| /// each time the user enters their LSKF, and cleared from memory each time the device is locked. |
| /// Symmetric. |
| pub const USER_SCREEN_LOCK_BOUND_KEY: SuperKeyType = SuperKeyType { |
| alias: "USER_SCREEN_LOCK_BOUND_KEY", |
| algorithm: SuperEncryptionAlgorithm::Aes256Gcm, |
| }; |
| /// Key used for ScreenLockBound keys; the corresponding superencryption key is loaded in memory |
| /// each time the user enters their LSKF, and cleared from memory each time the device is locked. |
| /// Asymmetric, so keys can be encrypted when the device is locked. |
| pub const USER_SCREEN_LOCK_BOUND_ECDH_KEY: SuperKeyType = SuperKeyType { |
| alias: "USER_SCREEN_LOCK_BOUND_ECDH_KEY", |
| algorithm: SuperEncryptionAlgorithm::EcdhP256, |
| }; |
| |
| /// Superencryption to apply to a new key. |
| #[derive(Debug, Clone, Copy)] |
| pub enum SuperEncryptionType { |
| /// Do not superencrypt this key. |
| None, |
| /// Superencrypt with a key that remains in memory from first unlock to reboot. |
| LskfBound, |
| /// Superencrypt with a key cleared from memory when the device is locked. |
| ScreenLockBound, |
| /// Superencrypt with a key based on the desired boot level |
| BootLevel(i32), |
| } |
| |
| #[derive(Debug, Clone, Copy)] |
| pub enum SuperKeyIdentifier { |
| /// id of the super key in the database. |
| DatabaseId(i64), |
| /// Boot level of the encrypting boot level key |
| BootLevel(i32), |
| } |
| |
| impl SuperKeyIdentifier { |
| fn from_metadata(metadata: &BlobMetaData) -> Option<Self> { |
| if let Some(EncryptedBy::KeyId(key_id)) = metadata.encrypted_by() { |
| Some(SuperKeyIdentifier::DatabaseId(*key_id)) |
| } else if let Some(boot_level) = metadata.max_boot_level() { |
| Some(SuperKeyIdentifier::BootLevel(*boot_level)) |
| } else { |
| None |
| } |
| } |
| |
| fn add_to_metadata(&self, metadata: &mut BlobMetaData) { |
| match self { |
| SuperKeyIdentifier::DatabaseId(id) => { |
| metadata.add(BlobMetaEntry::EncryptedBy(EncryptedBy::KeyId(*id))); |
| } |
| SuperKeyIdentifier::BootLevel(level) => { |
| metadata.add(BlobMetaEntry::MaxBootLevel(*level)); |
| } |
| } |
| } |
| } |
| |
| pub struct SuperKey { |
| algorithm: SuperEncryptionAlgorithm, |
| key: ZVec, |
| /// Identifier of the encrypting key, used to write an encrypted blob |
| /// back to the database after re-encryption eg on a key update. |
| id: SuperKeyIdentifier, |
| /// ECDH is more expensive than AES. So on ECDH private keys we set the |
| /// reencrypt_with field to point at the corresponding AES key, and the |
| /// keys will be re-encrypted with AES on first use. |
| reencrypt_with: Option<Arc<SuperKey>>, |
| } |
| |
| impl SuperKey { |
| /// For most purposes `unwrap_key` handles decryption, |
| /// but legacy handling and some tests need to assume AES and decrypt directly. |
| pub fn aes_gcm_decrypt(&self, data: &[u8], iv: &[u8], tag: &[u8]) -> Result<ZVec> { |
| if self.algorithm == SuperEncryptionAlgorithm::Aes256Gcm { |
| aes_gcm_decrypt(data, iv, tag, &self.key) |
| .context("In aes_gcm_decrypt: decryption failed") |
| } else { |
| Err(Error::sys()).context("In aes_gcm_decrypt: Key is not an AES key") |
| } |
| } |
| } |
| |
| /// A SuperKey that has been encrypted with an AES-GCM key. For |
| /// encryption the key is in memory, and for decryption it is in KM. |
| struct LockedKey { |
| algorithm: SuperEncryptionAlgorithm, |
| id: SuperKeyIdentifier, |
| nonce: Vec<u8>, |
| ciphertext: Vec<u8>, // with tag appended |
| } |
| |
| impl LockedKey { |
| fn new(key: &[u8], to_encrypt: &Arc<SuperKey>) -> Result<Self> { |
| let (mut ciphertext, nonce, mut tag) = aes_gcm_encrypt(&to_encrypt.key, key)?; |
| ciphertext.append(&mut tag); |
| Ok(LockedKey { algorithm: to_encrypt.algorithm, id: to_encrypt.id, nonce, ciphertext }) |
| } |
| |
| fn decrypt( |
| &self, |
| db: &mut KeystoreDB, |
| km_dev: &KeyMintDevice, |
| key_id_guard: &KeyIdGuard, |
| key_entry: &KeyEntry, |
| auth_token: &HardwareAuthToken, |
| reencrypt_with: Option<Arc<SuperKey>>, |
| ) -> Result<Arc<SuperKey>> { |
| let key_params = vec![ |
| KeyParameterValue::Algorithm(Algorithm::AES), |
| KeyParameterValue::KeySize(256), |
| KeyParameterValue::BlockMode(BlockMode::GCM), |
| KeyParameterValue::PaddingMode(PaddingMode::NONE), |
| KeyParameterValue::Nonce(self.nonce.clone()), |
| KeyParameterValue::MacLength(128), |
| ]; |
| let key_params: Vec<KmKeyParameter> = key_params.into_iter().map(|x| x.into()).collect(); |
| let key = ZVec::try_from(km_dev.use_key_in_one_step( |
| db, |
| key_id_guard, |
| key_entry, |
| KeyPurpose::DECRYPT, |
| &key_params, |
| Some(auth_token), |
| &self.ciphertext, |
| )?)?; |
| Ok(Arc::new(SuperKey { algorithm: self.algorithm, key, id: self.id, reencrypt_with })) |
| } |
| } |
| |
| /// Keys for unlocking UNLOCKED_DEVICE_REQUIRED keys, as LockedKeys, complete with |
| /// a database descriptor for the encrypting key and the sids for the auth tokens |
| /// that can be used to decrypt it. |
| struct BiometricUnlock { |
| /// List of auth token SIDs that can be used to unlock these keys. |
| sids: Vec<i64>, |
| /// Database descriptor of key to use to unlock. |
| key_desc: KeyDescriptor, |
| /// Locked versions of the matching UserSuperKeys fields |
| screen_lock_bound: LockedKey, |
| screen_lock_bound_private: LockedKey, |
| } |
| |
| #[derive(Default)] |
| struct UserSuperKeys { |
| /// The per boot key is used for LSKF binding of authentication bound keys. There is one |
| /// key per android user. The key is stored on flash encrypted with a key derived from a |
| /// secret, that is itself derived from the user's lock screen knowledge factor (LSKF). |
| /// When the user unlocks the device for the first time, this key is unlocked, i.e., decrypted, |
| /// and stays memory resident until the device reboots. |
| per_boot: Option<Arc<SuperKey>>, |
| /// The screen lock key works like the per boot key with the distinction that it is cleared |
| /// from memory when the screen lock is engaged. |
| screen_lock_bound: Option<Arc<SuperKey>>, |
| /// When the device is locked, screen-lock-bound keys can still be encrypted, using |
| /// ECDH public-key encryption. This field holds the decryption private key. |
| screen_lock_bound_private: Option<Arc<SuperKey>>, |
| /// Versions of the above two keys, locked behind a biometric. |
| biometric_unlock: Option<BiometricUnlock>, |
| } |
| |
| #[derive(Default)] |
| struct SkmState { |
| user_keys: HashMap<UserId, UserSuperKeys>, |
| key_index: HashMap<i64, Weak<SuperKey>>, |
| boot_level_key_cache: Option<BootLevelKeyCache>, |
| } |
| |
| impl SkmState { |
| fn add_key_to_key_index(&mut self, super_key: &Arc<SuperKey>) -> Result<()> { |
| if let SuperKeyIdentifier::DatabaseId(id) = super_key.id { |
| self.key_index.insert(id, Arc::downgrade(super_key)); |
| Ok(()) |
| } else { |
| Err(Error::sys()).context(format!( |
| "In add_key_to_key_index: cannot add key with ID {:?}", |
| super_key.id |
| )) |
| } |
| } |
| } |
| |
| #[derive(Default)] |
| pub struct SuperKeyManager { |
| data: Mutex<SkmState>, |
| } |
| |
| impl SuperKeyManager { |
| pub fn set_up_boot_level_cache(self: &Arc<Self>, db: &mut KeystoreDB) -> Result<()> { |
| let mut data = self.data.lock().unwrap(); |
| if data.boot_level_key_cache.is_some() { |
| log::info!("In set_up_boot_level_cache: called for a second time"); |
| return Ok(()); |
| } |
| let level_zero_key = get_level_zero_key(db) |
| .context("In set_up_boot_level_cache: get_level_zero_key failed")?; |
| data.boot_level_key_cache = Some(BootLevelKeyCache::new(level_zero_key)); |
| log::info!("Starting boot level watcher."); |
| let clone = self.clone(); |
| std::thread::spawn(move || { |
| clone |
| .watch_boot_level() |
| .unwrap_or_else(|e| log::error!("watch_boot_level failed:\n{:?}", e)); |
| }); |
| Ok(()) |
| } |
| |
| /// Watch the `keystore.boot_level` system property, and keep boot level up to date. |
| /// Blocks waiting for system property changes, so must be run in its own thread. |
| fn watch_boot_level(&self) -> Result<()> { |
| let mut w = PropertyWatcher::new("keystore.boot_level") |
| .context("In watch_boot_level: PropertyWatcher::new failed")?; |
| loop { |
| let level = w |
| .read(|_n, v| v.parse::<usize>().map_err(std::convert::Into::into)) |
| .context("In watch_boot_level: read of property failed")?; |
| // watch_boot_level should only be called once data.boot_level_key_cache is Some, |
| // so it's safe to unwrap in the branches below. |
| if level < MAX_MAX_BOOT_LEVEL { |
| log::info!("Read keystore.boot_level value {}", level); |
| let mut data = self.data.lock().unwrap(); |
| data.boot_level_key_cache |
| .as_mut() |
| .unwrap() |
| .advance_boot_level(level) |
| .context("In watch_boot_level: advance_boot_level failed")?; |
| } else { |
| log::info!( |
| "keystore.boot_level {} hits maximum {}, finishing.", |
| level, |
| MAX_MAX_BOOT_LEVEL |
| ); |
| let mut data = self.data.lock().unwrap(); |
| data.boot_level_key_cache.as_mut().unwrap().finish(); |
| break; |
| } |
| w.wait().context("In watch_boot_level: property wait failed")?; |
| } |
| Ok(()) |
| } |
| |
| pub fn level_accessible(&self, boot_level: i32) -> bool { |
| self.data |
| .lock() |
| .unwrap() |
| .boot_level_key_cache |
| .as_ref() |
| .map_or(false, |c| c.level_accessible(boot_level as usize)) |
| } |
| |
| pub fn forget_all_keys_for_user(&self, user: UserId) { |
| let mut data = self.data.lock().unwrap(); |
| data.user_keys.remove(&user); |
| } |
| |
| fn install_per_boot_key_for_user(&self, user: UserId, super_key: Arc<SuperKey>) -> Result<()> { |
| let mut data = self.data.lock().unwrap(); |
| data.add_key_to_key_index(&super_key) |
| .context("In install_per_boot_key_for_user: add_key_to_key_index failed")?; |
| data.user_keys.entry(user).or_default().per_boot = Some(super_key); |
| Ok(()) |
| } |
| |
| fn lookup_key(&self, key_id: &SuperKeyIdentifier) -> Result<Option<Arc<SuperKey>>> { |
| let mut data = self.data.lock().unwrap(); |
| Ok(match key_id { |
| SuperKeyIdentifier::DatabaseId(id) => data.key_index.get(id).and_then(|k| k.upgrade()), |
| SuperKeyIdentifier::BootLevel(level) => data |
| .boot_level_key_cache |
| .as_mut() |
| .map(|b| b.aes_key(*level as usize)) |
| .transpose() |
| .context("In lookup_key: aes_key failed")? |
| .flatten() |
| .map(|key| { |
| Arc::new(SuperKey { |
| algorithm: SuperEncryptionAlgorithm::Aes256Gcm, |
| key, |
| id: *key_id, |
| reencrypt_with: None, |
| }) |
| }), |
| }) |
| } |
| |
| pub fn get_per_boot_key_by_user_id(&self, user_id: UserId) -> Option<Arc<SuperKey>> { |
| let data = self.data.lock().unwrap(); |
| data.user_keys.get(&user_id).and_then(|e| e.per_boot.as_ref().cloned()) |
| } |
| |
| /// This function unlocks the super keys for a given user. |
| /// This means the key is loaded from the database, decrypted and placed in the |
| /// super key cache. If there is no such key a new key is created, encrypted with |
| /// a key derived from the given password and stored in the database. |
| pub fn unlock_user_key( |
| &self, |
| db: &mut KeystoreDB, |
| user: UserId, |
| pw: &Password, |
| legacy_blob_loader: &LegacyBlobLoader, |
| ) -> Result<()> { |
| let (_, entry) = db |
| .get_or_create_key_with( |
| Domain::APP, |
| user as u64 as i64, |
| &USER_SUPER_KEY.alias, |
| crate::database::KEYSTORE_UUID, |
| || { |
| // For backward compatibility we need to check if there is a super key present. |
| let super_key = legacy_blob_loader |
| .load_super_key(user, pw) |
| .context("In create_new_key: Failed to load legacy key blob.")?; |
| let super_key = match super_key { |
| None => { |
| // No legacy file was found. So we generate a new key. |
| generate_aes256_key() |
| .context("In create_new_key: Failed to generate AES 256 key.")? |
| } |
| Some(key) => key, |
| }; |
| // Regardless of whether we loaded an old AES128 key or generated a new AES256 |
| // key as the super key, we derive a AES256 key from the password and re-encrypt |
| // the super key before we insert it in the database. The length of the key is |
| // preserved by the encryption so we don't need any extra flags to inform us |
| // which algorithm to use it with. |
| Self::encrypt_with_password(&super_key, pw).context("In create_new_key.") |
| }, |
| ) |
| .context("In unlock_user_key: Failed to get key id.")?; |
| |
| self.populate_cache_from_super_key_blob(user, USER_SUPER_KEY.algorithm, entry, pw) |
| .context("In unlock_user_key.")?; |
| Ok(()) |
| } |
| |
| /// Check if a given key is super-encrypted, from its metadata. If so, unwrap the key using |
| /// the relevant super key. |
| pub fn unwrap_key_if_required<'a>( |
| &self, |
| metadata: &BlobMetaData, |
| blob: &'a [u8], |
| ) -> Result<KeyBlob<'a>> { |
| Ok(if let Some(key_id) = SuperKeyIdentifier::from_metadata(metadata) { |
| let super_key = self |
| .lookup_key(&key_id) |
| .context("In unwrap_key: lookup_key failed")? |
| .ok_or(Error::Rc(ResponseCode::LOCKED)) |
| .context("In unwrap_key: Required super decryption key is not in memory.")?; |
| KeyBlob::Sensitive { |
| key: Self::unwrap_key_with_key(blob, metadata, &super_key) |
| .context("In unwrap_key: unwrap_key_with_key failed")?, |
| reencrypt_with: super_key.reencrypt_with.as_ref().unwrap_or(&super_key).clone(), |
| force_reencrypt: super_key.reencrypt_with.is_some(), |
| } |
| } else { |
| KeyBlob::Ref(blob) |
| }) |
| } |
| |
| /// Unwraps an encrypted key blob given an encryption key. |
| fn unwrap_key_with_key(blob: &[u8], metadata: &BlobMetaData, key: &SuperKey) -> Result<ZVec> { |
| match key.algorithm { |
| SuperEncryptionAlgorithm::Aes256Gcm => match (metadata.iv(), metadata.aead_tag()) { |
| (Some(iv), Some(tag)) => key |
| .aes_gcm_decrypt(blob, iv, tag) |
| .context("In unwrap_key_with_key: Failed to decrypt the key blob."), |
| (iv, tag) => Err(Error::Rc(ResponseCode::VALUE_CORRUPTED)).context(format!( |
| concat!( |
| "In unwrap_key_with_key: Key has incomplete metadata.", |
| "Present: iv: {}, aead_tag: {}." |
| ), |
| iv.is_some(), |
| tag.is_some(), |
| )), |
| }, |
| SuperEncryptionAlgorithm::EcdhP256 => { |
| match (metadata.public_key(), metadata.salt(), metadata.iv(), metadata.aead_tag()) { |
| (Some(public_key), Some(salt), Some(iv), Some(aead_tag)) => { |
| ECDHPrivateKey::from_private_key(&key.key) |
| .and_then(|k| k.decrypt_message(public_key, salt, iv, blob, aead_tag)) |
| .context( |
| "In unwrap_key_with_key: Failed to decrypt the key blob with ECDH.", |
| ) |
| } |
| (public_key, salt, iv, aead_tag) => { |
| Err(Error::Rc(ResponseCode::VALUE_CORRUPTED)).context(format!( |
| concat!( |
| "In unwrap_key_with_key: Key has incomplete metadata.", |
| "Present: public_key: {}, salt: {}, iv: {}, aead_tag: {}." |
| ), |
| public_key.is_some(), |
| salt.is_some(), |
| iv.is_some(), |
| aead_tag.is_some(), |
| )) |
| } |
| } |
| } |
| } |
| } |
| |
| /// Checks if user has setup LSKF, even when super key cache is empty for the user. |
| pub fn super_key_exists_in_db_for_user( |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| user_id: UserId, |
| ) -> Result<bool> { |
| let key_in_db = db |
| .key_exists(Domain::APP, user_id as u64 as i64, &USER_SUPER_KEY.alias, KeyType::Super) |
| .context("In super_key_exists_in_db_for_user.")?; |
| |
| if key_in_db { |
| Ok(key_in_db) |
| } else { |
| legacy_migrator |
| .has_super_key(user_id) |
| .context("In super_key_exists_in_db_for_user: Trying to query legacy db.") |
| } |
| } |
| |
| /// Checks if user has already setup LSKF (i.e. a super key is persisted in the database or the |
| /// legacy database). If not, return Uninitialized state. |
| /// Otherwise, decrypt the super key from the password and return LskfUnlocked state. |
| pub fn check_and_unlock_super_key( |
| &self, |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| user_id: UserId, |
| pw: &Password, |
| ) -> Result<UserState> { |
| let alias = &USER_SUPER_KEY; |
| let result = legacy_migrator |
| .with_try_migrate_super_key(user_id, pw, || db.load_super_key(alias, user_id)) |
| .context("In check_and_unlock_super_key. Failed to load super key")?; |
| |
| match result { |
| Some((_, entry)) => { |
| let super_key = self |
| .populate_cache_from_super_key_blob(user_id, alias.algorithm, entry, pw) |
| .context("In check_and_unlock_super_key.")?; |
| Ok(UserState::LskfUnlocked(super_key)) |
| } |
| None => Ok(UserState::Uninitialized), |
| } |
| } |
| |
| /// Checks if user has already setup LSKF (i.e. a super key is persisted in the database or the |
| /// legacy database). If so, return LskfLocked state. |
| /// If the password is provided, generate a new super key, encrypt with the password, |
| /// store in the database and populate the super key cache for the new user |
| /// and return LskfUnlocked state. |
| /// If the password is not provided, return Uninitialized state. |
| pub fn check_and_initialize_super_key( |
| &self, |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| user_id: UserId, |
| pw: Option<&Password>, |
| ) -> Result<UserState> { |
| let super_key_exists_in_db = |
| Self::super_key_exists_in_db_for_user(db, legacy_migrator, user_id).context( |
| "In check_and_initialize_super_key. Failed to check if super key exists.", |
| )?; |
| if super_key_exists_in_db { |
| Ok(UserState::LskfLocked) |
| } else if let Some(pw) = pw { |
| //generate a new super key. |
| let super_key = generate_aes256_key() |
| .context("In check_and_initialize_super_key: Failed to generate AES 256 key.")?; |
| //derive an AES256 key from the password and re-encrypt the super key |
| //before we insert it in the database. |
| let (encrypted_super_key, blob_metadata) = Self::encrypt_with_password(&super_key, pw) |
| .context("In check_and_initialize_super_key.")?; |
| |
| let key_entry = db |
| .store_super_key( |
| user_id, |
| &USER_SUPER_KEY, |
| &encrypted_super_key, |
| &blob_metadata, |
| &KeyMetaData::new(), |
| ) |
| .context("In check_and_initialize_super_key. Failed to store super key.")?; |
| |
| let super_key = self |
| .populate_cache_from_super_key_blob( |
| user_id, |
| USER_SUPER_KEY.algorithm, |
| key_entry, |
| pw, |
| ) |
| .context("In check_and_initialize_super_key.")?; |
| Ok(UserState::LskfUnlocked(super_key)) |
| } else { |
| Ok(UserState::Uninitialized) |
| } |
| } |
| |
| //helper function to populate super key cache from the super key blob loaded from the database |
| fn populate_cache_from_super_key_blob( |
| &self, |
| user_id: UserId, |
| algorithm: SuperEncryptionAlgorithm, |
| entry: KeyEntry, |
| pw: &Password, |
| ) -> Result<Arc<SuperKey>> { |
| let super_key = Self::extract_super_key_from_key_entry(algorithm, entry, pw, None) |
| .context( |
| "In populate_cache_from_super_key_blob. Failed to extract super key from key entry", |
| )?; |
| self.install_per_boot_key_for_user(user_id, super_key.clone())?; |
| Ok(super_key) |
| } |
| |
| /// Extracts super key from the entry loaded from the database |
| pub fn extract_super_key_from_key_entry( |
| algorithm: SuperEncryptionAlgorithm, |
| entry: KeyEntry, |
| pw: &Password, |
| reencrypt_with: Option<Arc<SuperKey>>, |
| ) -> Result<Arc<SuperKey>> { |
| if let Some((blob, metadata)) = entry.key_blob_info() { |
| let key = match ( |
| metadata.encrypted_by(), |
| metadata.salt(), |
| metadata.iv(), |
| metadata.aead_tag(), |
| ) { |
| (Some(&EncryptedBy::Password), Some(salt), Some(iv), Some(tag)) => { |
| // Note that password encryption is AES no matter the value of algorithm |
| let key = pw.derive_key(Some(salt), AES_256_KEY_LENGTH).context( |
| "In extract_super_key_from_key_entry: Failed to generate key from password.", |
| )?; |
| |
| aes_gcm_decrypt(blob, iv, tag, &key).context( |
| "In extract_super_key_from_key_entry: Failed to decrypt key blob.", |
| )? |
| } |
| (enc_by, salt, iv, tag) => { |
| return Err(Error::Rc(ResponseCode::VALUE_CORRUPTED)).context(format!( |
| concat!( |
| "In extract_super_key_from_key_entry: Super key has incomplete metadata.", |
| "encrypted_by: {:?}; Present: salt: {}, iv: {}, aead_tag: {}." |
| ), |
| enc_by, |
| salt.is_some(), |
| iv.is_some(), |
| tag.is_some() |
| )); |
| } |
| }; |
| Ok(Arc::new(SuperKey { |
| algorithm, |
| key, |
| id: SuperKeyIdentifier::DatabaseId(entry.id()), |
| reencrypt_with, |
| })) |
| } else { |
| Err(Error::Rc(ResponseCode::VALUE_CORRUPTED)) |
| .context("In extract_super_key_from_key_entry: No key blob info.") |
| } |
| } |
| |
| /// Encrypts the super key from a key derived from the password, before storing in the database. |
| pub fn encrypt_with_password( |
| super_key: &[u8], |
| pw: &Password, |
| ) -> Result<(Vec<u8>, BlobMetaData)> { |
| let salt = generate_salt().context("In encrypt_with_password: Failed to generate salt.")?; |
| let derived_key = pw |
| .derive_key(Some(&salt), AES_256_KEY_LENGTH) |
| .context("In encrypt_with_password: Failed to derive password.")?; |
| let mut metadata = BlobMetaData::new(); |
| metadata.add(BlobMetaEntry::EncryptedBy(EncryptedBy::Password)); |
| metadata.add(BlobMetaEntry::Salt(salt)); |
| let (encrypted_key, iv, tag) = aes_gcm_encrypt(super_key, &derived_key) |
| .context("In encrypt_with_password: Failed to encrypt new super key.")?; |
| metadata.add(BlobMetaEntry::Iv(iv)); |
| metadata.add(BlobMetaEntry::AeadTag(tag)); |
| Ok((encrypted_key, metadata)) |
| } |
| |
| // Encrypt the given key blob with the user's super key, if the super key exists and the device |
| // is unlocked. If the super key exists and the device is locked, or LSKF is not setup, |
| // return error. Note that it is out of the scope of this function to check if super encryption |
| // is required. Such check should be performed before calling this function. |
| fn super_encrypt_on_key_init( |
| &self, |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| user_id: UserId, |
| key_blob: &[u8], |
| ) -> Result<(Vec<u8>, BlobMetaData)> { |
| match UserState::get(db, legacy_migrator, self, user_id) |
| .context("In super_encrypt. Failed to get user state.")? |
| { |
| UserState::LskfUnlocked(super_key) => { |
| Self::encrypt_with_aes_super_key(key_blob, &super_key) |
| .context("In super_encrypt_on_key_init. Failed to encrypt the key.") |
| } |
| UserState::LskfLocked => { |
| Err(Error::Rc(ResponseCode::LOCKED)).context("In super_encrypt. Device is locked.") |
| } |
| UserState::Uninitialized => Err(Error::Rc(ResponseCode::UNINITIALIZED)) |
| .context("In super_encrypt. LSKF is not setup for the user."), |
| } |
| } |
| |
| //Helper function to encrypt a key with the given super key. Callers should select which super |
| //key to be used. This is called when a key is super encrypted at its creation as well as at its |
| //upgrade. |
| fn encrypt_with_aes_super_key( |
| key_blob: &[u8], |
| super_key: &SuperKey, |
| ) -> Result<(Vec<u8>, BlobMetaData)> { |
| if super_key.algorithm != SuperEncryptionAlgorithm::Aes256Gcm { |
| return Err(Error::sys()) |
| .context("In encrypt_with_aes_super_key: unexpected algorithm"); |
| } |
| let mut metadata = BlobMetaData::new(); |
| let (encrypted_key, iv, tag) = aes_gcm_encrypt(key_blob, &(super_key.key)) |
| .context("In encrypt_with_aes_super_key: Failed to encrypt new super key.")?; |
| metadata.add(BlobMetaEntry::Iv(iv)); |
| metadata.add(BlobMetaEntry::AeadTag(tag)); |
| super_key.id.add_to_metadata(&mut metadata); |
| Ok((encrypted_key, metadata)) |
| } |
| |
| /// Check if super encryption is required and if so, super-encrypt the key to be stored in |
| /// the database. |
| #[allow(clippy::too_many_arguments)] |
| pub fn handle_super_encryption_on_key_init( |
| &self, |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| domain: &Domain, |
| key_parameters: &[KeyParameter], |
| flags: Option<i32>, |
| user_id: UserId, |
| key_blob: &[u8], |
| ) -> Result<(Vec<u8>, BlobMetaData)> { |
| match Enforcements::super_encryption_required(domain, key_parameters, flags) { |
| SuperEncryptionType::None => Ok((key_blob.to_vec(), BlobMetaData::new())), |
| SuperEncryptionType::LskfBound => self |
| .super_encrypt_on_key_init(db, legacy_migrator, user_id, &key_blob) |
| .context(concat!( |
| "In handle_super_encryption_on_key_init. ", |
| "Failed to super encrypt with LskfBound key." |
| )), |
| SuperEncryptionType::ScreenLockBound => { |
| let mut data = self.data.lock().unwrap(); |
| let entry = data.user_keys.entry(user_id).or_default(); |
| if let Some(super_key) = entry.screen_lock_bound.as_ref() { |
| Self::encrypt_with_aes_super_key(key_blob, &super_key).context(concat!( |
| "In handle_super_encryption_on_key_init. ", |
| "Failed to encrypt with ScreenLockBound key." |
| )) |
| } else { |
| // Symmetric key is not available, use public key encryption |
| let loaded = |
| db.load_super_key(&USER_SCREEN_LOCK_BOUND_ECDH_KEY, user_id).context( |
| "In handle_super_encryption_on_key_init: load_super_key failed.", |
| )?; |
| let (key_id_guard, key_entry) = loaded.ok_or_else(Error::sys).context( |
| "In handle_super_encryption_on_key_init: User ECDH key missing.", |
| )?; |
| let public_key = |
| key_entry.metadata().sec1_public_key().ok_or_else(Error::sys).context( |
| "In handle_super_encryption_on_key_init: sec1_public_key missing.", |
| )?; |
| let mut metadata = BlobMetaData::new(); |
| let (ephem_key, salt, iv, encrypted_key, aead_tag) = |
| ECDHPrivateKey::encrypt_message(public_key, key_blob).context(concat!( |
| "In handle_super_encryption_on_key_init: ", |
| "ECDHPrivateKey::encrypt_message failed." |
| ))?; |
| metadata.add(BlobMetaEntry::PublicKey(ephem_key)); |
| metadata.add(BlobMetaEntry::Salt(salt)); |
| metadata.add(BlobMetaEntry::Iv(iv)); |
| metadata.add(BlobMetaEntry::AeadTag(aead_tag)); |
| SuperKeyIdentifier::DatabaseId(key_id_guard.id()) |
| .add_to_metadata(&mut metadata); |
| Ok((encrypted_key, metadata)) |
| } |
| } |
| SuperEncryptionType::BootLevel(level) => { |
| let key_id = SuperKeyIdentifier::BootLevel(level); |
| let super_key = self |
| .lookup_key(&key_id) |
| .context("In handle_super_encryption_on_key_init: lookup_key failed")? |
| .ok_or(Error::Rc(ResponseCode::LOCKED)) |
| .context("In handle_super_encryption_on_key_init: Boot stage key absent")?; |
| Self::encrypt_with_aes_super_key(key_blob, &super_key).context(concat!( |
| "In handle_super_encryption_on_key_init: ", |
| "Failed to encrypt with BootLevel key." |
| )) |
| } |
| } |
| } |
| |
| /// Check if a given key needs re-super-encryption, from its KeyBlob type. |
| /// If so, re-super-encrypt the key and return a new set of metadata, |
| /// containing the new super encryption information. |
| pub fn reencrypt_if_required<'a>( |
| key_blob_before_upgrade: &KeyBlob, |
| key_after_upgrade: &'a [u8], |
| ) -> Result<(KeyBlob<'a>, Option<BlobMetaData>)> { |
| match key_blob_before_upgrade { |
| KeyBlob::Sensitive { reencrypt_with: super_key, .. } => { |
| let (key, metadata) = |
| Self::encrypt_with_aes_super_key(key_after_upgrade, super_key) |
| .context("In reencrypt_if_required: Failed to re-super-encrypt key.")?; |
| Ok((KeyBlob::NonSensitive(key), Some(metadata))) |
| } |
| _ => Ok((KeyBlob::Ref(key_after_upgrade), None)), |
| } |
| } |
| |
| /// Fetch a superencryption key from the database, or create it if it doesn't already exist. |
| /// When this is called, the caller must hold the lock on the SuperKeyManager. |
| /// So it's OK that the check and creation are different DB transactions. |
| fn get_or_create_super_key( |
| db: &mut KeystoreDB, |
| user_id: UserId, |
| key_type: &SuperKeyType, |
| password: &Password, |
| reencrypt_with: Option<Arc<SuperKey>>, |
| ) -> Result<Arc<SuperKey>> { |
| let loaded_key = db.load_super_key(key_type, user_id)?; |
| if let Some((_, key_entry)) = loaded_key { |
| Ok(Self::extract_super_key_from_key_entry( |
| key_type.algorithm, |
| key_entry, |
| password, |
| reencrypt_with, |
| )?) |
| } else { |
| let (super_key, public_key) = match key_type.algorithm { |
| SuperEncryptionAlgorithm::Aes256Gcm => ( |
| generate_aes256_key() |
| .context("In get_or_create_super_key: Failed to generate AES 256 key.")?, |
| None, |
| ), |
| SuperEncryptionAlgorithm::EcdhP256 => { |
| let key = ECDHPrivateKey::generate() |
| .context("In get_or_create_super_key: Failed to generate ECDH key")?; |
| ( |
| key.private_key() |
| .context("In get_or_create_super_key: private_key failed")?, |
| Some( |
| key.public_key() |
| .context("In get_or_create_super_key: public_key failed")?, |
| ), |
| ) |
| } |
| }; |
| //derive an AES256 key from the password and re-encrypt the super key |
| //before we insert it in the database. |
| let (encrypted_super_key, blob_metadata) = |
| Self::encrypt_with_password(&super_key, password) |
| .context("In get_or_create_super_key.")?; |
| let mut key_metadata = KeyMetaData::new(); |
| if let Some(pk) = public_key { |
| key_metadata.add(KeyMetaEntry::Sec1PublicKey(pk)); |
| } |
| let key_entry = db |
| .store_super_key( |
| user_id, |
| key_type, |
| &encrypted_super_key, |
| &blob_metadata, |
| &key_metadata, |
| ) |
| .context("In get_or_create_super_key. Failed to store super key.")?; |
| Ok(Arc::new(SuperKey { |
| algorithm: key_type.algorithm, |
| key: super_key, |
| id: SuperKeyIdentifier::DatabaseId(key_entry.id()), |
| reencrypt_with, |
| })) |
| } |
| } |
| |
| /// Decrypt the screen-lock bound keys for this user using the password and store in memory. |
| pub fn unlock_screen_lock_bound_key( |
| &self, |
| db: &mut KeystoreDB, |
| user_id: UserId, |
| password: &Password, |
| ) -> Result<()> { |
| let mut data = self.data.lock().unwrap(); |
| let entry = data.user_keys.entry(user_id).or_default(); |
| let aes = entry |
| .screen_lock_bound |
| .get_or_try_to_insert_with(|| { |
| Self::get_or_create_super_key( |
| db, |
| user_id, |
| &USER_SCREEN_LOCK_BOUND_KEY, |
| password, |
| None, |
| ) |
| })? |
| .clone(); |
| let ecdh = entry |
| .screen_lock_bound_private |
| .get_or_try_to_insert_with(|| { |
| Self::get_or_create_super_key( |
| db, |
| user_id, |
| &USER_SCREEN_LOCK_BOUND_ECDH_KEY, |
| password, |
| Some(aes.clone()), |
| ) |
| })? |
| .clone(); |
| data.add_key_to_key_index(&aes)?; |
| data.add_key_to_key_index(&ecdh)?; |
| Ok(()) |
| } |
| |
| /// Wipe the screen-lock bound keys for this user from memory. |
| pub fn lock_screen_lock_bound_key( |
| &self, |
| db: &mut KeystoreDB, |
| user_id: UserId, |
| unlocking_sids: &[i64], |
| ) { |
| log::info!("Locking screen bound for user {} sids {:?}", user_id, unlocking_sids); |
| let mut data = self.data.lock().unwrap(); |
| let mut entry = data.user_keys.entry(user_id).or_default(); |
| if !unlocking_sids.is_empty() { |
| if let (Some(aes), Some(ecdh)) = ( |
| entry.screen_lock_bound.as_ref().cloned(), |
| entry.screen_lock_bound_private.as_ref().cloned(), |
| ) { |
| let res = (|| -> Result<()> { |
| let key_desc = KeyMintDevice::internal_descriptor(format!( |
| "biometric_unlock_key_{}", |
| user_id |
| )); |
| let encrypting_key = generate_aes256_key()?; |
| let km_dev: KeyMintDevice = |
| KeyMintDevice::get(SecurityLevel::TRUSTED_ENVIRONMENT) |
| .context("In lock_screen_lock_bound_key: KeyMintDevice::get failed")?; |
| let mut key_params = vec![ |
| KeyParameterValue::Algorithm(Algorithm::AES), |
| KeyParameterValue::KeySize(256), |
| KeyParameterValue::BlockMode(BlockMode::GCM), |
| KeyParameterValue::PaddingMode(PaddingMode::NONE), |
| KeyParameterValue::CallerNonce, |
| KeyParameterValue::KeyPurpose(KeyPurpose::DECRYPT), |
| KeyParameterValue::MinMacLength(128), |
| KeyParameterValue::AuthTimeout(BIOMETRIC_AUTH_TIMEOUT_S), |
| KeyParameterValue::HardwareAuthenticatorType( |
| HardwareAuthenticatorType::FINGERPRINT, |
| ), |
| ]; |
| for sid in unlocking_sids { |
| key_params.push(KeyParameterValue::UserSecureID(*sid)); |
| } |
| let key_params: Vec<KmKeyParameter> = |
| key_params.into_iter().map(|x| x.into()).collect(); |
| km_dev.create_and_store_key(db, &key_desc, |dev| { |
| let _wp = wd::watch_millis( |
| "In lock_screen_lock_bound_key: calling importKey.", |
| 500, |
| ); |
| dev.importKey(key_params.as_slice(), KeyFormat::RAW, &encrypting_key, None) |
| })?; |
| entry.biometric_unlock = Some(BiometricUnlock { |
| sids: unlocking_sids.into(), |
| key_desc, |
| screen_lock_bound: LockedKey::new(&encrypting_key, &aes)?, |
| screen_lock_bound_private: LockedKey::new(&encrypting_key, &ecdh)?, |
| }); |
| Ok(()) |
| })(); |
| // There is no reason to propagate an error here upwards. We must discard |
| // entry.screen_lock_bound* in any case. |
| if let Err(e) = res { |
| log::error!("Error setting up biometric unlock: {:#?}", e); |
| } |
| } |
| } |
| entry.screen_lock_bound = None; |
| entry.screen_lock_bound_private = None; |
| } |
| |
| /// User has unlocked, not using a password. See if any of our stored auth tokens can be used |
| /// to unlock the keys protecting UNLOCKED_DEVICE_REQUIRED keys. |
| pub fn try_unlock_user_with_biometric( |
| &self, |
| db: &mut KeystoreDB, |
| user_id: UserId, |
| ) -> Result<()> { |
| let mut data = self.data.lock().unwrap(); |
| let mut entry = data.user_keys.entry(user_id).or_default(); |
| if let Some(biometric) = entry.biometric_unlock.as_ref() { |
| let (key_id_guard, key_entry) = |
| KeyMintDevice::lookup_from_desc(db, &biometric.key_desc)?; |
| let km_dev: KeyMintDevice = KeyMintDevice::get(SecurityLevel::TRUSTED_ENVIRONMENT) |
| .context("In try_unlock_user_with_biometric: KeyMintDevice::get failed")?; |
| for sid in &biometric.sids { |
| if let Some((auth_token_entry, _)) = db.find_auth_token_entry(|entry| { |
| entry.auth_token().userId == *sid || entry.auth_token().authenticatorId == *sid |
| })? { |
| let res: Result<(Arc<SuperKey>, Arc<SuperKey>)> = (|| { |
| let slb = biometric.screen_lock_bound.decrypt( |
| db, |
| &km_dev, |
| &key_id_guard, |
| &key_entry, |
| auth_token_entry.auth_token(), |
| None, |
| )?; |
| let slbp = biometric.screen_lock_bound_private.decrypt( |
| db, |
| &km_dev, |
| &key_id_guard, |
| &key_entry, |
| auth_token_entry.auth_token(), |
| Some(slb.clone()), |
| )?; |
| Ok((slb, slbp)) |
| })(); |
| match res { |
| Ok((slb, slbp)) => { |
| entry.screen_lock_bound = Some(slb.clone()); |
| entry.screen_lock_bound_private = Some(slbp.clone()); |
| data.add_key_to_key_index(&slb)?; |
| data.add_key_to_key_index(&slbp)?; |
| log::info!(concat!( |
| "In try_unlock_user_with_biometric: ", |
| "Successfully unlocked with biometric" |
| )); |
| return Ok(()); |
| } |
| Err(e) => { |
| log::warn!("In try_unlock_user_with_biometric: attempt failed: {:?}", e) |
| } |
| } |
| } |
| } |
| } |
| Ok(()) |
| } |
| } |
| |
| /// This enum represents different states of the user's life cycle in the device. |
| /// For now, only three states are defined. More states may be added later. |
| pub enum UserState { |
| // The user has registered LSKF and has unlocked the device by entering PIN/Password, |
| // and hence the per-boot super key is available in the cache. |
| LskfUnlocked(Arc<SuperKey>), |
| // The user has registered LSKF, but has not unlocked the device using password, after reboot. |
| // Hence the per-boot super-key(s) is not available in the cache. |
| // However, the encrypted super key is available in the database. |
| LskfLocked, |
| // There's no user in the device for the given user id, or the user with the user id has not |
| // setup LSKF. |
| Uninitialized, |
| } |
| |
| impl UserState { |
| pub fn get( |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| skm: &SuperKeyManager, |
| user_id: UserId, |
| ) -> Result<UserState> { |
| match skm.get_per_boot_key_by_user_id(user_id) { |
| Some(super_key) => Ok(UserState::LskfUnlocked(super_key)), |
| None => { |
| //Check if a super key exists in the database or legacy database. |
| //If so, return locked user state. |
| if SuperKeyManager::super_key_exists_in_db_for_user(db, legacy_migrator, user_id) |
| .context("In get.")? |
| { |
| Ok(UserState::LskfLocked) |
| } else { |
| Ok(UserState::Uninitialized) |
| } |
| } |
| } |
| } |
| |
| /// Queries user state when serving password change requests. |
| pub fn get_with_password_changed( |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| skm: &SuperKeyManager, |
| user_id: UserId, |
| password: Option<&Password>, |
| ) -> Result<UserState> { |
| match skm.get_per_boot_key_by_user_id(user_id) { |
| Some(super_key) => { |
| if password.is_none() { |
| //transitioning to swiping, delete only the super key in database and cache, and |
| //super-encrypted keys in database (and in KM) |
| Self::reset_user(db, skm, legacy_migrator, user_id, true).context( |
| "In get_with_password_changed: Trying to delete keys from the db.", |
| )?; |
| //Lskf is now removed in Keystore |
| Ok(UserState::Uninitialized) |
| } else { |
| //Keystore won't be notified when changing to a new password when LSKF is |
| //already setup. Therefore, ideally this path wouldn't be reached. |
| Ok(UserState::LskfUnlocked(super_key)) |
| } |
| } |
| None => { |
| //Check if a super key exists in the database or legacy database. |
| //If so, return LskfLocked state. |
| //Otherwise, i) if the password is provided, initialize the super key and return |
| //LskfUnlocked state ii) if password is not provided, return Uninitialized state. |
| skm.check_and_initialize_super_key(db, legacy_migrator, user_id, password) |
| } |
| } |
| } |
| |
| /// Queries user state when serving password unlock requests. |
| pub fn get_with_password_unlock( |
| db: &mut KeystoreDB, |
| legacy_migrator: &LegacyMigrator, |
| skm: &SuperKeyManager, |
| user_id: UserId, |
| password: &Password, |
| ) -> Result<UserState> { |
| match skm.get_per_boot_key_by_user_id(user_id) { |
| Some(super_key) => { |
| log::info!("In get_with_password_unlock. Trying to unlock when already unlocked."); |
| Ok(UserState::LskfUnlocked(super_key)) |
| } |
| None => { |
| //Check if a super key exists in the database or legacy database. |
| //If not, return Uninitialized state. |
| //Otherwise, try to unlock the super key and if successful, |
| //return LskfUnlocked state |
| skm.check_and_unlock_super_key(db, legacy_migrator, user_id, password) |
| .context("In get_with_password_unlock. Failed to unlock super key.") |
| } |
| } |
| } |
| |
| /// Delete all the keys created on behalf of the user. |
| /// If 'keep_non_super_encrypted_keys' is set to true, delete only the super key and super |
| /// encrypted keys. |
| pub fn reset_user( |
| db: &mut KeystoreDB, |
| skm: &SuperKeyManager, |
| legacy_migrator: &LegacyMigrator, |
| user_id: UserId, |
| keep_non_super_encrypted_keys: bool, |
| ) -> Result<()> { |
| // mark keys created on behalf of the user as unreferenced. |
| legacy_migrator |
| .bulk_delete_user(user_id, keep_non_super_encrypted_keys) |
| .context("In reset_user: Trying to delete legacy keys.")?; |
| db.unbind_keys_for_user(user_id, keep_non_super_encrypted_keys) |
| .context("In reset user. Error in unbinding keys.")?; |
| |
| //delete super key in cache, if exists |
| skm.forget_all_keys_for_user(user_id); |
| Ok(()) |
| } |
| } |
| |
| /// This enum represents three states a KeyMint Blob can be in, w.r.t super encryption. |
| /// `Sensitive` holds the non encrypted key and a reference to its super key. |
| /// `NonSensitive` holds a non encrypted key that is never supposed to be encrypted. |
| /// `Ref` holds a reference to a key blob when it does not need to be modified if its |
| /// life time allows it. |
| pub enum KeyBlob<'a> { |
| Sensitive { |
| key: ZVec, |
| /// If KeyMint reports that the key must be upgraded, we must |
| /// re-encrypt the key before writing to the database; we use |
| /// this key. |
| reencrypt_with: Arc<SuperKey>, |
| /// If this key was decrypted with an ECDH key, we want to |
| /// re-encrypt it on first use whether it was upgraded or not; |
| /// this field indicates that that's necessary. |
| force_reencrypt: bool, |
| }, |
| NonSensitive(Vec<u8>), |
| Ref(&'a [u8]), |
| } |
| |
| impl<'a> KeyBlob<'a> { |
| pub fn force_reencrypt(&self) -> bool { |
| if let KeyBlob::Sensitive { force_reencrypt, .. } = self { |
| *force_reencrypt |
| } else { |
| false |
| } |
| } |
| } |
| |
| /// Deref returns a reference to the key material in any variant. |
| impl<'a> Deref for KeyBlob<'a> { |
| type Target = [u8]; |
| |
| fn deref(&self) -> &Self::Target { |
| match self { |
| Self::Sensitive { key, .. } => &key, |
| Self::NonSensitive(key) => &key, |
| Self::Ref(key) => key, |
| } |
| } |
| } |