RecoveryController.java revision 745d2c98f9467f1befb7ec3a6c485333d4f1b437
1/* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.security.keystore.recovery; 18 19import android.annotation.NonNull; 20import android.annotation.Nullable; 21import android.annotation.RequiresPermission; 22import android.annotation.SystemApi; 23import android.app.KeyguardManager; 24import android.app.PendingIntent; 25import android.content.Context; 26import android.content.pm.PackageManager.NameNotFoundException; 27import android.os.RemoteException; 28import android.os.ServiceManager; 29import android.os.ServiceSpecificException; 30import android.security.KeyStore; 31import android.security.keystore.AndroidKeyStoreProvider; 32 33import com.android.internal.widget.ILockSettings; 34 35import java.security.Key; 36import java.security.UnrecoverableKeyException; 37import java.security.cert.CertPath; 38import java.security.cert.CertificateException; 39import java.security.cert.X509Certificate; 40import java.util.ArrayList; 41import java.util.List; 42import java.util.Map; 43 44/** 45 * Backs up cryptographic keys to remote secure hardware, encrypted with the user's lock screen. 46 * 47 * <p>A system app with the {@code android.permission.RECOVER_KEYSTORE} permission may generate or 48 * import recoverable keys using this class. To generate a key, the app must call 49 * {@link #generateKey(String)} with the desired alias for the key. This returns an AndroidKeyStore 50 * reference to a 256-bit {@link javax.crypto.SecretKey}, which can be used for AES/GCM/NoPadding. 51 * In order to get the same key again at a later time, the app can call {@link #getKey(String)} with 52 * the same alias. If a key is generated in this way the key's raw material is never directly 53 * exposed to the calling app. The system app may also import key material using 54 * {@link #importKey(String, byte[])}. The app may only generate and import keys for its own 55 * {@code uid}. 56 * 57 * <p>The same system app must also register a Recovery Agent to manage syncing recoverable keys to 58 * remote secure hardware. The Recovery Agent is a service that registers itself with the controller 59 * as follows: 60 * 61 * <ul> 62 * <li>Invokes {@link #initRecoveryService(String, byte[], byte[])} 63 * <ul> 64 * <li>The first argument is the alias of the root certificate used to verify trusted 65 * hardware modules. Each trusted hardware module must have a public key signed with this 66 * root of trust. Roots of trust must be shipped with the framework. The app can list all 67 * valid roots of trust by calling {@link #getRootCertificates()}. 68 * <li>The second argument is the UTF-8 bytes of the XML listing file. It lists the X509 69 * certificates containing the public keys of all available remote trusted hardware modules. 70 * Each of the X509 certificates can be validated against the chosen root of trust. 71 * <li>The third argument is the UTF-8 bytes of the XML signing file. The file contains a 72 * signature of the XML listing file. The signature can be validated against the chosen root 73 * of trust. 74 * </ul> 75 * <p>This will cause the controller to choose a random public key from the list. From then 76 * on the controller will attempt to sync the key chain with the trusted hardware module to whom 77 * that key belongs. 78 * <li>Invokes {@link #setServerParams(byte[])} with a byte string that identifies the device 79 * to a remote server. This server may act as the front-end to the trusted hardware modules. It 80 * is up to the Recovery Agent to decide how best to identify devices, but this could be, e.g., 81 * based on the <a href="https://developers.google.com/instance-id/">Instance ID</a> of the 82 * system app. 83 * <li>Invokes {@link #setRecoverySecretTypes(int[])} with a list of types of secret used to 84 * secure the recoverable key chain. For now only 85 * {@link KeyChainProtectionParams#TYPE_LOCKSCREEN} is supported. 86 * <li>Invokes {@link #setSnapshotCreatedPendingIntent(PendingIntent)} with a 87 * {@link PendingIntent} that is to be invoked whenever a new snapshot is created. Although the 88 * controller can create snapshots without the Recovery Agent registering this intent, it is a 89 * good idea to register the intent so that the Recovery Agent is able to sync this snapshot to 90 * the trusted hardware module as soon as it is available. 91 * </ul> 92 * 93 * <p>The trusted hardware module's public key MUST be generated on secure hardware with protections 94 * equivalent to those described in the 95 * <a href="https://developer.android.com/preview/features/security/ckv-whitepaper.html">Google 96 * Cloud Key Vault Service whitepaper</a>. The trusted hardware module itself must protect the key 97 * chain from brute-forcing using the methods also described in the whitepaper: i.e., it should 98 * limit the number of allowed attempts to enter the lock screen. If the number of attempts is 99 * exceeded the key material must no longer be recoverable. 100 * 101 * <p>A recoverable key chain snapshot is considered pending if any of the following conditions 102 * are met: 103 * 104 * <ul> 105 * <li>The system app mutates the key chain. i.e., generates, imports, or removes a key. 106 * <li>The user changes their lock screen. 107 * </ul> 108 * 109 * <p>Whenever the user unlocks their device, if a snapshot is pending, the Recovery Controller 110 * generates a new snapshot. It follows these steps to do so: 111 * 112 * <ul> 113 * <li>Generates a 256-bit AES key using {@link java.security.SecureRandom}. This is the 114 * Recovery Key. 115 * <li>Wraps the key material of all keys in the recoverable key chain with the Recovery Key. 116 * <li>Encrypts the Recovery Key with both the public key of the trusted hardware module and a 117 * symmetric key derived from the user's lock screen. 118 * </ul> 119 * 120 * <p>The controller then writes this snapshot to disk, and uses the {@link PendingIntent} that was 121 * set by the Recovery Agent during initialization to inform it that a new snapshot is available. 122 * The snapshot only contains keys for that Recovery Agent's {@code uid} - i.e., keys the agent's 123 * app itself generated. If multiple Recovery Agents exist on the device, each will be notified of 124 * their new snapshots, and each snapshots' keys will be only those belonging to the same 125 * {@code uid}. 126 * 127 * <p>The Recovery Agent retrieves its most recent snapshot by calling 128 * {@link #getKeyChainSnapshot()}. It syncs the snapshot to the remote server. The snapshot contains 129 * the public key used for encryption, which the server uses to forward the encrypted recovery key 130 * to the correct trusted hardware module. The snapshot also contains the server params, which are 131 * used to identify this device to the server. 132 * 133 * <p>The client uses the server params to identify a device whose key chain it wishes to restore. 134 * This may be on a different device to the device that originally synced the key chain. The client 135 * sends the server params identifying the previous device to the server. The server returns the 136 * X509 certificate identifying the trusted hardware module in which the encrypted Recovery Key is 137 * stored. It also returns some vault parameters identifying that particular Recovery Key to the 138 * trusted hardware module. And it also returns a vault challenge, which is used as part of the 139 * vault opening protocol to ensure the recovery claim is fresh. See the whitepaper for more 140 * details. 141 * 142 * <p>The key chain is recovered via a {@link RecoverySession}. A Recovery Agent creates one by 143 * invoking {@link #createRecoverySession()}. It then invokes 144 * {@link RecoverySession#start(String, CertPath, byte[], byte[], List)} with these arguments: 145 * 146 * <ul> 147 * <li>The alias of the root of trust used to verify the trusted hardware module. 148 * <li>The X509 certificate of the trusted hardware module. 149 * <li>The vault parameters used to identify the Recovery Key to the trusted hardware module. 150 * <li>The vault challenge, as issued by the trusted hardware module. 151 * <li>A list of secrets, corresponding to the secrets used to protect the key chain. At the 152 * moment this is a single {@link KeyChainProtectionParams} containing the lock screen of the 153 * device whose key chain is to be recovered. 154 * </ul> 155 * 156 * <p>This method returns a byte array containing the Recovery Claim, which can be issued to the 157 * remote trusted hardware module. It is encrypted with the trusted hardware module's public key 158 * (which has itself been certified with the root of trust). It also contains an ephemeral symmetric 159 * key generated for this recovery session, which the remote trusted hardware module uses to encrypt 160 * its responses. This is the Session Key. 161 * 162 * <p>If the lock screen provided is correct, the remote trusted hardware module decrypts one of the 163 * layers of lock-screen encryption from the Recovery Key. It then returns this key, encrypted with 164 * the Session Key to the Recovery Agent. As the Recovery Agent does not know the Session Key, it 165 * must then invoke {@link RecoverySession#recoverKeyChainSnapshot(byte[], List)} with the encrypted 166 * Recovery Key and the list of wrapped application keys. The controller then decrypts the layer of 167 * encryption provided by the Session Key, and uses the lock screen to decrypt the final layer of 168 * encryption. It then uses the Recovery Key to decrypt all of the wrapped application keys, and 169 * imports them into its own KeyStore. The Recovery Agent's app may then access these keys by 170 * calling {@link #getKey(String)}. Only this app's {@code uid} may access the keys that have been 171 * recovered. 172 * 173 * @hide 174 */ 175@SystemApi 176public class RecoveryController { 177 private static final String TAG = "RecoveryController"; 178 179 /** Key has been successfully synced. */ 180 public static final int RECOVERY_STATUS_SYNCED = 0; 181 /** Waiting for recovery agent to sync the key. */ 182 public static final int RECOVERY_STATUS_SYNC_IN_PROGRESS = 1; 183 /** Key cannot be synced. */ 184 public static final int RECOVERY_STATUS_PERMANENT_FAILURE = 3; 185 186 /** 187 * Failed because no snapshot is yet pending to be synced for the user. 188 * 189 * @hide 190 */ 191 public static final int ERROR_NO_SNAPSHOT_PENDING = 21; 192 193 /** 194 * Failed due to an error internal to the recovery service. This is unexpected and indicates 195 * either a problem with the logic in the service, or a problem with a dependency of the 196 * service (such as AndroidKeyStore). 197 * 198 * @hide 199 */ 200 public static final int ERROR_SERVICE_INTERNAL_ERROR = 22; 201 202 /** 203 * Failed because the user does not have a lock screen set. 204 * 205 * @hide 206 */ 207 public static final int ERROR_INSECURE_USER = 23; 208 209 /** 210 * Error thrown when attempting to use a recovery session that has since been closed. 211 * 212 * @hide 213 */ 214 public static final int ERROR_SESSION_EXPIRED = 24; 215 216 /** 217 * Failed because the format of the provided certificate is incorrect, e.g., cannot be decoded 218 * properly or misses necessary fields. 219 * 220 * <p>Note that this is different from {@link #ERROR_INVALID_CERTIFICATE}, which implies the 221 * certificate has a correct format but cannot be validated. 222 * 223 * @hide 224 */ 225 public static final int ERROR_BAD_CERTIFICATE_FORMAT = 25; 226 227 /** 228 * Error thrown if decryption failed. This might be because the tag is wrong, the key is wrong, 229 * the data has become corrupted, the data has been tampered with, etc. 230 * 231 * @hide 232 */ 233 public static final int ERROR_DECRYPTION_FAILED = 26; 234 235 /** 236 * Error thrown if the format of a given key is invalid. This might be because the key has a 237 * wrong length, invalid content, etc. 238 * 239 * @hide 240 */ 241 public static final int ERROR_INVALID_KEY_FORMAT = 27; 242 243 /** 244 * Failed because the provided certificate cannot be validated, e.g., is expired or has invalid 245 * signatures. 246 * 247 * <p>Note that this is different from {@link #ERROR_BAD_CERTIFICATE_FORMAT}, which denotes 248 * incorrect certificate formats, e.g., due to wrong encoding or structure. 249 * 250 * @hide 251 */ 252 public static final int ERROR_INVALID_CERTIFICATE = 28; 253 254 255 /** 256 * Failed because the provided certificate contained serial version which is lower that the 257 * version device is already initialized with. It is not possible to downgrade serial version of 258 * the provided certificate. 259 * 260 * @hide 261 */ 262 public static final int ERROR_DOWNGRADE_CERTIFICATE = 29; 263 264 private final ILockSettings mBinder; 265 private final KeyStore mKeyStore; 266 267 private RecoveryController(ILockSettings binder, KeyStore keystore) { 268 mBinder = binder; 269 mKeyStore = keystore; 270 } 271 272 /** 273 * Internal method used by {@code RecoverySession}. 274 * 275 * @hide 276 */ 277 ILockSettings getBinder() { 278 return mBinder; 279 } 280 281 /** 282 * Gets a new instance of the class. 283 */ 284 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 285 @NonNull public static RecoveryController getInstance(@NonNull Context context) { 286 ILockSettings lockSettings = 287 ILockSettings.Stub.asInterface(ServiceManager.getService("lock_settings")); 288 return new RecoveryController(lockSettings, KeyStore.getInstance()); 289 } 290 291 /** 292 * Checks whether the recoverable key store is currently available. 293 * 294 * <p>If it returns true, the device must currently be using a screen lock that is supported for 295 * use with the recoverable key store, i.e. AOSP PIN, pattern or password. 296 */ 297 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 298 public static boolean isRecoverableKeyStoreEnabled(@NonNull Context context) { 299 KeyguardManager keyguardManager = context.getSystemService(KeyguardManager.class); 300 return keyguardManager != null && keyguardManager.isDeviceSecure(); 301 } 302 303 /** 304 * @deprecated Use {@link #initRecoveryService(String, byte[], byte[])} instead. 305 * @removed 306 */ 307 @Deprecated 308 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 309 public void initRecoveryService( 310 @NonNull String rootCertificateAlias, @NonNull byte[] signedPublicKeyList) 311 throws CertificateException, InternalRecoveryServiceException { 312 throw new UnsupportedOperationException(); 313 } 314 315 /** 316 * Initializes the recovery service for the calling application. The detailed steps should be: 317 * <ol> 318 * <li>Parse {@code signatureFile} to get relevant information. 319 * <li>Validate the signer's X509 certificate, contained in {@code signatureFile}, against 320 * the root certificate pre-installed in the OS and chosen by {@code 321 * rootCertificateAlias}. 322 * <li>Verify the public-key signature, contained in {@code signatureFile}, and verify it 323 * against the entire {@code certificateFile}. 324 * <li>Parse {@code certificateFile} to get relevant information. 325 * <li>Check the serial number, contained in {@code certificateFile}, and skip the following 326 * steps if the serial number is not larger than the one previously stored. 327 * <li>Randomly choose a X509 certificate from the endpoint X509 certificates, contained in 328 * {@code certificateFile}, and validate it against the root certificate pre-installed 329 * in the OS and chosen by {@code rootCertificateAlias}. 330 * <li>Store the chosen X509 certificate and the serial in local database for later use. 331 * </ol> 332 * 333 * @param rootCertificateAlias the alias of a root certificate pre-installed in the OS 334 * @param certificateFile the binary content of the XML file containing a list of recovery 335 * service X509 certificates, and other metadata including the serial number 336 * @param signatureFile the binary content of the XML file containing the public-key signature 337 * of the entire certificate file, and a signer's X509 certificate 338 * @throws CertificateException if the given certificate files cannot be parsed or validated 339 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 340 * service. 341 */ 342 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 343 public void initRecoveryService( 344 @NonNull String rootCertificateAlias, @NonNull byte[] certificateFile, 345 @NonNull byte[] signatureFile) 346 throws CertificateException, InternalRecoveryServiceException { 347 try { 348 mBinder.initRecoveryServiceWithSigFile( 349 rootCertificateAlias, certificateFile, signatureFile); 350 } catch (RemoteException e) { 351 throw e.rethrowFromSystemServer(); 352 } catch (ServiceSpecificException e) { 353 if (e.errorCode == ERROR_BAD_CERTIFICATE_FORMAT 354 || e.errorCode == ERROR_INVALID_CERTIFICATE) { 355 throw new CertificateException("Invalid certificate for recovery service", e); 356 } 357 if (e.errorCode == ERROR_DOWNGRADE_CERTIFICATE) { 358 throw new CertificateException( 359 "Downgrading certificate serial version isn't supported.", e); 360 } 361 throw wrapUnexpectedServiceSpecificException(e); 362 } 363 } 364 365 /** 366 * @deprecated Use {@link #getKeyChainSnapshot()} 367 * @removed 368 */ 369 @Deprecated 370 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 371 public @Nullable KeyChainSnapshot getRecoveryData() throws InternalRecoveryServiceException { 372 throw new UnsupportedOperationException(); 373 } 374 375 /** 376 * Returns data necessary to store all recoverable keys. Key material is 377 * encrypted with user secret and recovery public key. 378 * 379 * @return Data necessary to recover keystore or {@code null} if snapshot is not available. 380 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 381 * service. 382 */ 383 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 384 public @Nullable KeyChainSnapshot getKeyChainSnapshot() 385 throws InternalRecoveryServiceException { 386 try { 387 return mBinder.getKeyChainSnapshot(); 388 } catch (RemoteException e) { 389 throw e.rethrowFromSystemServer(); 390 } catch (ServiceSpecificException e) { 391 if (e.errorCode == ERROR_NO_SNAPSHOT_PENDING) { 392 return null; 393 } 394 throw wrapUnexpectedServiceSpecificException(e); 395 } 396 } 397 398 /** 399 * Sets a listener which notifies recovery agent that new recovery snapshot is available. {@link 400 * #getKeyChainSnapshot} can be used to get the snapshot. Note that every recovery agent can 401 * have at most one registered listener at any time. 402 * 403 * @param intent triggered when new snapshot is available. Unregisters listener if the value is 404 * {@code null}. 405 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 406 * service. 407 */ 408 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 409 public void setSnapshotCreatedPendingIntent(@Nullable PendingIntent intent) 410 throws InternalRecoveryServiceException { 411 try { 412 mBinder.setSnapshotCreatedPendingIntent(intent); 413 } catch (RemoteException e) { 414 throw e.rethrowFromSystemServer(); 415 } catch (ServiceSpecificException e) { 416 throw wrapUnexpectedServiceSpecificException(e); 417 } 418 } 419 420 /** 421 * Server parameters used to generate new recovery key blobs. This value will be included in 422 * {@code KeyChainSnapshot.getEncryptedRecoveryKeyBlob()}. The same value must be included 423 * in vaultParams {@link RecoverySession#start(CertPath, byte[], byte[], List)}. 424 * 425 * @param serverParams included in recovery key blob. 426 * @see #getKeyChainSnapshot 427 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 428 * service. 429 */ 430 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 431 public void setServerParams(@NonNull byte[] serverParams) 432 throws InternalRecoveryServiceException { 433 try { 434 mBinder.setServerParams(serverParams); 435 } catch (RemoteException e) { 436 throw e.rethrowFromSystemServer(); 437 } catch (ServiceSpecificException e) { 438 throw wrapUnexpectedServiceSpecificException(e); 439 } 440 } 441 442 /** 443 * @deprecated Use {@link #getAliases()}. 444 * @removed 445 */ 446 @Deprecated 447 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 448 public List<String> getAliases(@Nullable String packageName) 449 throws InternalRecoveryServiceException { 450 throw new UnsupportedOperationException(); 451 } 452 453 /** 454 * Returns a list of aliases of keys belonging to the application. 455 */ 456 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 457 public @NonNull List<String> getAliases() throws InternalRecoveryServiceException { 458 try { 459 Map<String, Integer> allStatuses = mBinder.getRecoveryStatus(); 460 return new ArrayList<>(allStatuses.keySet()); 461 } catch (RemoteException e) { 462 throw e.rethrowFromSystemServer(); 463 } catch (ServiceSpecificException e) { 464 throw wrapUnexpectedServiceSpecificException(e); 465 } 466 } 467 468 /** 469 * @deprecated Use {@link #setRecoveryStatus(String, int)} 470 * @removed 471 */ 472 @Deprecated 473 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 474 public void setRecoveryStatus( 475 @NonNull String packageName, String alias, int status) 476 throws NameNotFoundException, InternalRecoveryServiceException { 477 throw new UnsupportedOperationException(); 478 } 479 480 /** 481 * Sets the recovery status for given key. It is used to notify the keystore that the key was 482 * successfully stored on the server or that there was an error. An application can check this 483 * value using {@link #getRecoveryStatus(String, String)}. 484 * 485 * @param alias The alias of the key whose status to set. 486 * @param status The status of the key. One of {@link #RECOVERY_STATUS_SYNCED}, 487 * {@link #RECOVERY_STATUS_SYNC_IN_PROGRESS} or {@link #RECOVERY_STATUS_PERMANENT_FAILURE}. 488 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 489 * service. 490 */ 491 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 492 public void setRecoveryStatus(@NonNull String alias, int status) 493 throws InternalRecoveryServiceException { 494 try { 495 mBinder.setRecoveryStatus(alias, status); 496 } catch (RemoteException e) { 497 throw e.rethrowFromSystemServer(); 498 } catch (ServiceSpecificException e) { 499 throw wrapUnexpectedServiceSpecificException(e); 500 } 501 } 502 503 /** 504 * @deprecated Use {@link #getRecoveryStatus(String)}. 505 * @removed 506 */ 507 @Deprecated 508 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 509 public int getRecoveryStatus(String packageName, String alias) 510 throws InternalRecoveryServiceException { 511 throw new UnsupportedOperationException(); 512 } 513 514 /** 515 * Returns the recovery status for the key with the given {@code alias}. 516 * 517 * <ul> 518 * <li>{@link #RECOVERY_STATUS_SYNCED} 519 * <li>{@link #RECOVERY_STATUS_SYNC_IN_PROGRESS} 520 * <li>{@link #RECOVERY_STATUS_PERMANENT_FAILURE} 521 * </ul> 522 * 523 * @see #setRecoveryStatus(String, int) 524 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 525 * service. 526 */ 527 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 528 public int getRecoveryStatus(@NonNull String alias) throws InternalRecoveryServiceException { 529 try { 530 Map<String, Integer> allStatuses = mBinder.getRecoveryStatus(); 531 Integer status = allStatuses.get(alias); 532 if (status == null) { 533 return RecoveryController.RECOVERY_STATUS_PERMANENT_FAILURE; 534 } else { 535 return status; 536 } 537 } catch (RemoteException e) { 538 throw e.rethrowFromSystemServer(); 539 } catch (ServiceSpecificException e) { 540 throw wrapUnexpectedServiceSpecificException(e); 541 } 542 } 543 544 /** 545 * Specifies a set of secret types used for end-to-end keystore encryption. Knowing all of them 546 * is necessary to recover data. 547 * 548 * @param secretTypes {@link KeyChainProtectionParams#TYPE_LOCKSCREEN} 549 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 550 * service. 551 */ 552 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 553 public void setRecoverySecretTypes( 554 @NonNull @KeyChainProtectionParams.UserSecretType int[] secretTypes) 555 throws InternalRecoveryServiceException { 556 try { 557 mBinder.setRecoverySecretTypes(secretTypes); 558 } catch (RemoteException e) { 559 throw e.rethrowFromSystemServer(); 560 } catch (ServiceSpecificException e) { 561 throw wrapUnexpectedServiceSpecificException(e); 562 } 563 } 564 565 /** 566 * Defines a set of secret types used for end-to-end keystore encryption. Knowing all of them is 567 * necessary to generate KeyChainSnapshot. 568 * 569 * @return list of recovery secret types 570 * @see KeyChainSnapshot 571 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 572 * service. 573 */ 574 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 575 public @NonNull @KeyChainProtectionParams.UserSecretType int[] getRecoverySecretTypes() 576 throws InternalRecoveryServiceException { 577 try { 578 return mBinder.getRecoverySecretTypes(); 579 } catch (RemoteException e) { 580 throw e.rethrowFromSystemServer(); 581 } catch (ServiceSpecificException e) { 582 throw wrapUnexpectedServiceSpecificException(e); 583 } 584 } 585 586 /** 587 * Deprecated. 588 * Generates a AES256/GCM/NoPADDING key called {@code alias} and loads it into the recoverable 589 * key store. Returns the raw material of the key. 590 * 591 * @param alias The key alias. 592 * @param account The account associated with the key 593 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 594 * service. 595 * @throws LockScreenRequiredException if the user has not set a lock screen. This is required 596 * to generate recoverable keys, as the snapshots are encrypted using a key derived from the 597 * lock screen. 598 * @deprecated Use {@link #generateKey(String)} 599 * @removed 600 */ 601 @Deprecated 602 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 603 public byte[] generateAndStoreKey(@NonNull String alias, byte[] account) 604 throws InternalRecoveryServiceException, LockScreenRequiredException { 605 throw new UnsupportedOperationException("Operation is not supported, use generateKey"); 606 } 607 608 /** 609 * @deprecated Use {@link #generateKey(String)}. 610 * @removed 611 */ 612 @Deprecated 613 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 614 public Key generateKey(@NonNull String alias, byte[] account) 615 throws InternalRecoveryServiceException, LockScreenRequiredException { 616 throw new UnsupportedOperationException(); 617 } 618 619 /** 620 * Generates a recoverable key with the given {@code alias}. 621 * 622 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 623 * service. 624 * @throws LockScreenRequiredException if the user does not have a lock screen set. A lock 625 * screen is required to generate recoverable keys. 626 */ 627 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 628 public @NonNull Key generateKey(@NonNull String alias) throws InternalRecoveryServiceException, 629 LockScreenRequiredException { 630 try { 631 String grantAlias = mBinder.generateKey(alias); 632 if (grantAlias == null) { 633 throw new InternalRecoveryServiceException("null grant alias"); 634 } 635 return getKeyFromGrant(grantAlias); 636 } catch (RemoteException e) { 637 throw e.rethrowFromSystemServer(); 638 } catch (UnrecoverableKeyException e) { 639 throw new InternalRecoveryServiceException("Failed to get key from keystore", e); 640 } catch (ServiceSpecificException e) { 641 if (e.errorCode == ERROR_INSECURE_USER) { 642 throw new LockScreenRequiredException(e.getMessage()); 643 } 644 throw wrapUnexpectedServiceSpecificException(e); 645 } 646 } 647 648 /** 649 * Imports a 256-bit recoverable AES key with the given {@code alias} and the raw bytes {@code 650 * keyBytes}. 651 * 652 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 653 * service. 654 * @throws LockScreenRequiredException if the user does not have a lock screen set. A lock 655 * screen is required to generate recoverable keys. 656 * 657 */ 658 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 659 public @NonNull Key importKey(@NonNull String alias, @NonNull byte[] keyBytes) 660 throws InternalRecoveryServiceException, LockScreenRequiredException { 661 try { 662 String grantAlias = mBinder.importKey(alias, keyBytes); 663 if (grantAlias == null) { 664 throw new InternalRecoveryServiceException("Null grant alias"); 665 } 666 return getKeyFromGrant(grantAlias); 667 } catch (RemoteException e) { 668 throw e.rethrowFromSystemServer(); 669 } catch (UnrecoverableKeyException e) { 670 throw new InternalRecoveryServiceException("Failed to get key from keystore", e); 671 } catch (ServiceSpecificException e) { 672 if (e.errorCode == ERROR_INSECURE_USER) { 673 throw new LockScreenRequiredException(e.getMessage()); 674 } 675 throw wrapUnexpectedServiceSpecificException(e); 676 } 677 } 678 679 /** 680 * Gets a key called {@code alias} from the recoverable key store. 681 * 682 * @param alias The key alias. 683 * @return The key. 684 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 685 * service. 686 * @throws UnrecoverableKeyException if key is permanently invalidated or not found. 687 */ 688 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 689 public @Nullable Key getKey(@NonNull String alias) 690 throws InternalRecoveryServiceException, UnrecoverableKeyException { 691 try { 692 String grantAlias = mBinder.getKey(alias); 693 if (grantAlias == null || "".equals(grantAlias)) { 694 return null; 695 } 696 return getKeyFromGrant(grantAlias); 697 } catch (RemoteException e) { 698 throw e.rethrowFromSystemServer(); 699 } catch (ServiceSpecificException e) { 700 throw wrapUnexpectedServiceSpecificException(e); 701 } 702 } 703 704 /** 705 * Returns the key with the given {@code grantAlias}. 706 */ 707 @NonNull Key getKeyFromGrant(@NonNull String grantAlias) throws UnrecoverableKeyException { 708 return AndroidKeyStoreProvider.loadAndroidKeyStoreKeyFromKeystore( 709 mKeyStore, 710 grantAlias, 711 KeyStore.UID_SELF); 712 } 713 714 /** 715 * Removes a key called {@code alias} from the recoverable key store. 716 * 717 * @param alias The key alias. 718 * @throws InternalRecoveryServiceException if an unexpected error occurred in the recovery 719 * service. 720 */ 721 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 722 public void removeKey(@NonNull String alias) throws InternalRecoveryServiceException { 723 try { 724 mBinder.removeKey(alias); 725 } catch (RemoteException e) { 726 throw e.rethrowFromSystemServer(); 727 } catch (ServiceSpecificException e) { 728 throw wrapUnexpectedServiceSpecificException(e); 729 } 730 } 731 732 /** 733 * Returns a new {@link RecoverySession}. 734 * 735 * <p>A recovery session is required to restore keys from a remote store. 736 */ 737 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 738 public @NonNull RecoverySession createRecoverySession() { 739 return RecoverySession.newInstance(this); 740 } 741 742 @RequiresPermission(android.Manifest.permission.RECOVER_KEYSTORE) 743 public @NonNull Map<String, X509Certificate> getRootCertificates() { 744 return TrustedRootCertificates.getRootCertificates(); 745 } 746 747 InternalRecoveryServiceException wrapUnexpectedServiceSpecificException( 748 ServiceSpecificException e) { 749 if (e.errorCode == ERROR_SERVICE_INTERNAL_ERROR) { 750 return new InternalRecoveryServiceException(e.getMessage()); 751 } 752 753 // Should never happen. If it does, it's a bug, and we need to update how the method that 754 // called this throws its exceptions. 755 return new InternalRecoveryServiceException("Unexpected error code for method: " 756 + e.errorCode, e); 757 } 758} 759