1 /* 2 * Copyright (C) 2011 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 package android.security; 17 18 import android.annotation.NonNull; 19 import android.annotation.Nullable; 20 import android.annotation.WorkerThread; 21 import android.app.Activity; 22 import android.app.PendingIntent; 23 import android.content.ComponentName; 24 import android.content.Context; 25 import android.content.Intent; 26 import android.content.ServiceConnection; 27 import android.net.Uri; 28 import android.os.IBinder; 29 import android.os.Looper; 30 import android.os.Process; 31 import android.os.RemoteException; 32 import android.os.UserHandle; 33 import android.security.keystore.AndroidKeyStoreProvider; 34 import android.security.keystore.KeyProperties; 35 36 import java.io.ByteArrayInputStream; 37 import java.io.Closeable; 38 import java.security.Principal; 39 import java.security.PrivateKey; 40 import java.security.UnrecoverableKeyException; 41 import java.security.cert.Certificate; 42 import java.security.cert.CertificateException; 43 import java.security.cert.CertificateFactory; 44 import java.security.cert.X509Certificate; 45 import java.util.List; 46 import java.util.Locale; 47 import java.util.concurrent.BlockingQueue; 48 import java.util.concurrent.LinkedBlockingQueue; 49 50 import com.android.org.conscrypt.TrustedCertificateStore; 51 52 /** 53 * The {@code KeyChain} class provides access to private keys and 54 * their corresponding certificate chains in credential storage. 55 * 56 * <p>Applications accessing the {@code KeyChain} normally go through 57 * these steps: 58 * 59 * <ol> 60 * 61 * <li>Receive a callback from an {@link javax.net.ssl.X509KeyManager 62 * X509KeyManager} that a private key is requested. 63 * 64 * <li>Call {@link #choosePrivateKeyAlias 65 * choosePrivateKeyAlias} to allow the user to select from a 66 * list of currently available private keys and corresponding 67 * certificate chains. The chosen alias will be returned by the 68 * callback {@link KeyChainAliasCallback#alias}, or null if no private 69 * key is available or the user cancels the request. 70 * 71 * <li>Call {@link #getPrivateKey} and {@link #getCertificateChain} to 72 * retrieve the credentials to return to the corresponding {@link 73 * javax.net.ssl.X509KeyManager} callbacks. 74 * 75 * </ol> 76 * 77 * <p>An application may remember the value of a selected alias to 78 * avoid prompting the user with {@link #choosePrivateKeyAlias 79 * choosePrivateKeyAlias} on subsequent connections. If the alias is 80 * no longer valid, null will be returned on lookups using that value 81 * 82 * <p>An application can request the installation of private keys and 83 * certificates via the {@code Intent} provided by {@link 84 * #createInstallIntent}. Private keys installed via this {@code 85 * Intent} will be accessible via {@link #choosePrivateKeyAlias} while 86 * Certificate Authority (CA) certificates will be trusted by all 87 * applications through the default {@code X509TrustManager}. 88 */ 89 // TODO reference intent for credential installation when public 90 public final class KeyChain { 91 92 /** 93 * @hide Also used by KeyChainService implementation 94 */ 95 public static final String ACCOUNT_TYPE = "com.android.keychain"; 96 97 /** 98 * Package name for KeyChain chooser. 99 */ 100 private static final String KEYCHAIN_PACKAGE = "com.android.keychain"; 101 102 /** 103 * Action to bring up the KeyChainActivity 104 */ 105 private static final String ACTION_CHOOSER = "com.android.keychain.CHOOSER"; 106 107 /** 108 * Package name for the Certificate Installer. 109 */ 110 private static final String CERT_INSTALLER_PACKAGE = "com.android.certinstaller"; 111 112 /** 113 * Extra for use with {@link #ACTION_CHOOSER} 114 * @hide Also used by KeyChainActivity implementation 115 */ 116 public static final String EXTRA_RESPONSE = "response"; 117 118 /** 119 * Extra for use with {@link #ACTION_CHOOSER} 120 * @hide Also used by KeyChainActivity implementation 121 */ 122 public static final String EXTRA_URI = "uri"; 123 124 /** 125 * Extra for use with {@link #ACTION_CHOOSER} 126 * @hide Also used by KeyChainActivity implementation 127 */ 128 public static final String EXTRA_ALIAS = "alias"; 129 130 /** 131 * Extra for use with {@link #ACTION_CHOOSER} 132 * @hide Also used by KeyChainActivity implementation 133 */ 134 public static final String EXTRA_SENDER = "sender"; 135 136 /** 137 * Action to bring up the CertInstaller. 138 */ 139 private static final String ACTION_INSTALL = "android.credentials.INSTALL"; 140 141 /** 142 * Optional extra to specify a {@code String} credential name on 143 * the {@code Intent} returned by {@link #createInstallIntent}. 144 */ 145 // Compatible with old com.android.certinstaller.CredentialHelper.CERT_NAME_KEY 146 public static final String EXTRA_NAME = "name"; 147 148 /** 149 * Optional extra to specify an X.509 certificate to install on 150 * the {@code Intent} returned by {@link #createInstallIntent}. 151 * The extra value should be a PEM or ASN.1 DER encoded {@code 152 * byte[]}. An {@link X509Certificate} can be converted to DER 153 * encoded bytes with {@link X509Certificate#getEncoded}. 154 * 155 * <p>{@link #EXTRA_NAME} may be used to provide a default alias 156 * name for the installed certificate. 157 */ 158 // Compatible with old android.security.Credentials.CERTIFICATE 159 public static final String EXTRA_CERTIFICATE = "CERT"; 160 161 /** 162 * Optional extra for use with the {@code Intent} returned by 163 * {@link #createInstallIntent} to specify a PKCS#12 key store to 164 * install. The extra value should be a {@code byte[]}. The bytes 165 * may come from an external source or be generated with {@link 166 * java.security.KeyStore#store} on a "PKCS12" instance. 167 * 168 * <p>The user will be prompted for the password to load the key store. 169 * 170 * <p>The key store will be scanned for {@link 171 * java.security.KeyStore.PrivateKeyEntry} entries and both the 172 * private key and associated certificate chain will be installed. 173 * 174 * <p>{@link #EXTRA_NAME} may be used to provide a default alias 175 * name for the installed credentials. 176 */ 177 // Compatible with old android.security.Credentials.PKCS12 178 public static final String EXTRA_PKCS12 = "PKCS12"; 179 180 181 /** 182 * Broadcast Action: Indicates the trusted storage has changed. Sent when 183 * one of this happens: 184 * 185 * <ul> 186 * <li>a new CA is added, 187 * <li>an existing CA is removed or disabled, 188 * <li>a disabled CA is enabled, 189 * <li>trusted storage is reset (all user certs are cleared), 190 * <li>when permission to access a private key is changed. 191 * </ul> 192 */ 193 public static final String ACTION_STORAGE_CHANGED = "android.security.STORAGE_CHANGED"; 194 195 /** 196 * Returns an {@code Intent} that can be used for credential 197 * installation. The intent may be used without any extras, in 198 * which case the user will be able to install credentials from 199 * their own source. 200 * 201 * <p>Alternatively, {@link #EXTRA_CERTIFICATE} or {@link 202 * #EXTRA_PKCS12} maybe used to specify the bytes of an X.509 203 * certificate or a PKCS#12 key store for installation. These 204 * extras may be combined with {@link #EXTRA_NAME} to provide a 205 * default alias name for credentials being installed. 206 * 207 * <p>When used with {@link Activity#startActivityForResult}, 208 * {@link Activity#RESULT_OK} will be returned if a credential was 209 * successfully installed, otherwise {@link 210 * Activity#RESULT_CANCELED} will be returned. 211 */ 212 @NonNull 213 public static Intent createInstallIntent() { 214 Intent intent = new Intent(ACTION_INSTALL); 215 intent.setClassName(CERT_INSTALLER_PACKAGE, 216 "com.android.certinstaller.CertInstallerMain"); 217 return intent; 218 } 219 220 /** 221 * Launches an {@code Activity} for the user to select the alias 222 * for a private key and certificate pair for authentication. The 223 * selected alias or null will be returned via the 224 * KeyChainAliasCallback callback. 225 * 226 * <p>The device or profile owner can intercept this before the activity 227 * is shown, to pick a specific private key alias. 228 * 229 * <p>{@code keyTypes} and {@code issuers} may be used to 230 * highlight suggested choices to the user, although to cope with 231 * sometimes erroneous values provided by servers, the user may be 232 * able to override these suggestions. 233 * 234 * <p>{@code host} and {@code port} may be used to give the user 235 * more context about the server requesting the credentials. 236 * 237 * <p>{@code alias} allows the chooser to preselect an existing 238 * alias which will still be subject to user confirmation. 239 * 240 * @param activity The {@link Activity} context to use for 241 * launching the new sub-Activity to prompt the user to select 242 * a private key; used only to call startActivity(); must not 243 * be null. 244 * @param response Callback to invoke when the request completes; 245 * must not be null 246 * @param keyTypes The acceptable types of asymmetric keys such as 247 * "RSA" or "DSA", or a null array. 248 * @param issuers The acceptable certificate issuers for the 249 * certificate matching the private key, or null. 250 * @param host The host name of the server requesting the 251 * certificate, or null if unavailable. 252 * @param port The port number of the server requesting the 253 * certificate, or -1 if unavailable. 254 * @param alias The alias to preselect if available, or null if 255 * unavailable. 256 */ 257 public static void choosePrivateKeyAlias(@NonNull Activity activity, 258 @NonNull KeyChainAliasCallback response, 259 @KeyProperties.KeyAlgorithmEnum String[] keyTypes, Principal[] issuers, 260 @Nullable String host, int port, @Nullable String alias) { 261 Uri uri = null; 262 if (host != null) { 263 uri = new Uri.Builder() 264 .authority(host + (port != -1 ? ":" + port : "")) 265 .build(); 266 } 267 choosePrivateKeyAlias(activity, response, keyTypes, issuers, uri, alias); 268 } 269 270 /** 271 * Launches an {@code Activity} for the user to select the alias 272 * for a private key and certificate pair for authentication. The 273 * selected alias or null will be returned via the 274 * KeyChainAliasCallback callback. 275 * 276 * <p>The device or profile owner can intercept this before the activity 277 * is shown, to pick a specific private key alias.</p> 278 * 279 * <p>{@code keyTypes} and {@code issuers} may be used to 280 * highlight suggested choices to the user, although to cope with 281 * sometimes erroneous values provided by servers, the user may be 282 * able to override these suggestions. 283 * 284 * <p>{@code host} and {@code port} may be used to give the user 285 * more context about the server requesting the credentials. 286 * 287 * <p>{@code alias} allows the chooser to preselect an existing 288 * alias which will still be subject to user confirmation. 289 * 290 * @param activity The {@link Activity} context to use for 291 * launching the new sub-Activity to prompt the user to select 292 * a private key; used only to call startActivity(); must not 293 * be null. 294 * @param response Callback to invoke when the request completes; 295 * must not be null 296 * @param keyTypes The acceptable types of asymmetric keys such as 297 * "EC" or "RSA", or a null array. 298 * @param issuers The acceptable certificate issuers for the 299 * certificate matching the private key, or null. 300 * @param uri The full URI the server is requesting the certificate 301 * for, or null if unavailable. 302 * @param alias The alias to preselect if available, or null if 303 * unavailable. 304 */ 305 public static void choosePrivateKeyAlias(@NonNull Activity activity, 306 @NonNull KeyChainAliasCallback response, 307 @KeyProperties.KeyAlgorithmEnum String[] keyTypes, Principal[] issuers, 308 @Nullable Uri uri, @Nullable String alias) { 309 /* 310 * TODO currently keyTypes, issuers are unused. They are meant 311 * to follow the semantics and purpose of X509KeyManager 312 * method arguments. 313 * 314 * keyTypes would allow the list to be filtered and typically 315 * will be set correctly by the server. In practice today, 316 * most all users will want only RSA or EC, and usually 317 * only a small number of certs will be available. 318 * 319 * issuers is typically not useful. Some servers historically 320 * will send the entire list of public CAs known to the 321 * server. Others will send none. If this is used, if there 322 * are no matches after applying the constraint, it should be 323 * ignored. 324 */ 325 if (activity == null) { 326 throw new NullPointerException("activity == null"); 327 } 328 if (response == null) { 329 throw new NullPointerException("response == null"); 330 } 331 Intent intent = new Intent(ACTION_CHOOSER); 332 intent.setPackage(KEYCHAIN_PACKAGE); 333 intent.putExtra(EXTRA_RESPONSE, new AliasResponse(response)); 334 intent.putExtra(EXTRA_URI, uri); 335 intent.putExtra(EXTRA_ALIAS, alias); 336 // the PendingIntent is used to get calling package name 337 intent.putExtra(EXTRA_SENDER, PendingIntent.getActivity(activity, 0, new Intent(), 0)); 338 activity.startActivity(intent); 339 } 340 341 private static class AliasResponse extends IKeyChainAliasCallback.Stub { 342 private final KeyChainAliasCallback keyChainAliasResponse; 343 private AliasResponse(KeyChainAliasCallback keyChainAliasResponse) { 344 this.keyChainAliasResponse = keyChainAliasResponse; 345 } 346 @Override public void alias(String alias) { 347 keyChainAliasResponse.alias(alias); 348 } 349 } 350 351 /** 352 * Returns the {@code PrivateKey} for the requested alias, or null 353 * if no there is no result. 354 * 355 * <p> This method may block while waiting for a connection to another process, and must never 356 * be called from the main thread. 357 * 358 * @param alias The alias of the desired private key, typically returned via 359 * {@link KeyChainAliasCallback#alias}. 360 * @throws KeyChainException if the alias was valid but there was some problem accessing it. 361 * @throws IllegalStateException if called from the main thread. 362 */ 363 @Nullable @WorkerThread 364 public static PrivateKey getPrivateKey(@NonNull Context context, @NonNull String alias) 365 throws KeyChainException, InterruptedException { 366 if (alias == null) { 367 throw new NullPointerException("alias == null"); 368 } 369 KeyChainConnection keyChainConnection = bind(context); 370 try { 371 final IKeyChainService keyChainService = keyChainConnection.getService(); 372 final String keyId = keyChainService.requestPrivateKey(alias); 373 if (keyId == null) { 374 throw new KeyChainException("keystore had a problem"); 375 } 376 return AndroidKeyStoreProvider.loadAndroidKeyStorePrivateKeyFromKeystore( 377 KeyStore.getInstance(), keyId); 378 } catch (RemoteException e) { 379 throw new KeyChainException(e); 380 } catch (RuntimeException e) { 381 // only certain RuntimeExceptions can be propagated across the IKeyChainService call 382 throw new KeyChainException(e); 383 } catch (UnrecoverableKeyException e) { 384 throw new KeyChainException(e); 385 } finally { 386 keyChainConnection.close(); 387 } 388 } 389 390 /** 391 * Returns the {@code X509Certificate} chain for the requested 392 * alias, or null if no there is no result. 393 * 394 * <p> This method may block while waiting for a connection to another process, and must never 395 * be called from the main thread. 396 * 397 * @param alias The alias of the desired certificate chain, typically 398 * returned via {@link KeyChainAliasCallback#alias}. 399 * @throws KeyChainException if the alias was valid but there was some problem accessing it. 400 * @throws IllegalStateException if called from the main thread. 401 */ 402 @Nullable @WorkerThread 403 public static X509Certificate[] getCertificateChain(@NonNull Context context, 404 @NonNull String alias) throws KeyChainException, InterruptedException { 405 if (alias == null) { 406 throw new NullPointerException("alias == null"); 407 } 408 KeyChainConnection keyChainConnection = bind(context); 409 try { 410 IKeyChainService keyChainService = keyChainConnection.getService(); 411 412 final byte[] certificateBytes = keyChainService.getCertificate(alias); 413 if (certificateBytes == null) { 414 return null; 415 } 416 417 TrustedCertificateStore store = new TrustedCertificateStore(); 418 List<X509Certificate> chain = store 419 .getCertificateChain(toCertificate(certificateBytes)); 420 return chain.toArray(new X509Certificate[chain.size()]); 421 } catch (CertificateException e) { 422 throw new KeyChainException(e); 423 } catch (RemoteException e) { 424 throw new KeyChainException(e); 425 } catch (RuntimeException e) { 426 // only certain RuntimeExceptions can be propagated across the IKeyChainService call 427 throw new KeyChainException(e); 428 } finally { 429 keyChainConnection.close(); 430 } 431 } 432 433 /** 434 * Returns {@code true} if the current device's {@code KeyChain} supports a 435 * specific {@code PrivateKey} type indicated by {@code algorithm} (e.g., 436 * "RSA"). 437 */ 438 public static boolean isKeyAlgorithmSupported( 439 @NonNull @KeyProperties.KeyAlgorithmEnum String algorithm) { 440 final String algUpper = algorithm.toUpperCase(Locale.US); 441 return KeyProperties.KEY_ALGORITHM_EC.equals(algUpper) 442 || KeyProperties.KEY_ALGORITHM_RSA.equals(algUpper); 443 } 444 445 /** 446 * Returns {@code true} if the current device's {@code KeyChain} binds any 447 * {@code PrivateKey} of the given {@code algorithm} to the device once 448 * imported or generated. This can be used to tell if there is special 449 * hardware support that can be used to bind keys to the device in a way 450 * that makes it non-exportable. 451 * 452 * @deprecated Whether the key is bound to the secure hardware is known only 453 * once the key has been imported. To find out, use: 454 * <pre>{@code 455 * PrivateKey key = ...; // private key from KeyChain 456 * 457 * KeyFactory keyFactory = 458 * KeyFactory.getInstance(key.getAlgorithm(), "AndroidKeyStore"); 459 * KeyInfo keyInfo = keyFactory.getKeySpec(key, KeyInfo.class); 460 * if (keyInfo.isInsideSecureHardware()) { 461 * // The key is bound to the secure hardware of this Android 462 * }}</pre> 463 */ 464 @Deprecated 465 public static boolean isBoundKeyAlgorithm( 466 @NonNull @KeyProperties.KeyAlgorithmEnum String algorithm) { 467 if (!isKeyAlgorithmSupported(algorithm)) { 468 return false; 469 } 470 471 return KeyStore.getInstance().isHardwareBacked(algorithm); 472 } 473 474 /** @hide */ 475 @NonNull 476 public static X509Certificate toCertificate(@NonNull byte[] bytes) { 477 if (bytes == null) { 478 throw new IllegalArgumentException("bytes == null"); 479 } 480 try { 481 CertificateFactory certFactory = CertificateFactory.getInstance("X.509"); 482 Certificate cert = certFactory.generateCertificate(new ByteArrayInputStream(bytes)); 483 return (X509Certificate) cert; 484 } catch (CertificateException e) { 485 throw new AssertionError(e); 486 } 487 } 488 489 /** 490 * @hide for reuse by CertInstaller and Settings. 491 * @see KeyChain#bind 492 */ 493 public final static class KeyChainConnection implements Closeable { 494 private final Context context; 495 private final ServiceConnection serviceConnection; 496 private final IKeyChainService service; 497 private KeyChainConnection(Context context, 498 ServiceConnection serviceConnection, 499 IKeyChainService service) { 500 this.context = context; 501 this.serviceConnection = serviceConnection; 502 this.service = service; 503 } 504 @Override public void close() { 505 context.unbindService(serviceConnection); 506 } 507 public IKeyChainService getService() { 508 return service; 509 } 510 } 511 512 /** 513 * @hide for reuse by CertInstaller and Settings. 514 * 515 * Caller should call unbindService on the result when finished. 516 */ 517 @WorkerThread 518 public static KeyChainConnection bind(@NonNull Context context) throws InterruptedException { 519 return bindAsUser(context, Process.myUserHandle()); 520 } 521 522 /** 523 * @hide 524 */ 525 @WorkerThread 526 public static KeyChainConnection bindAsUser(@NonNull Context context, UserHandle user) 527 throws InterruptedException { 528 if (context == null) { 529 throw new NullPointerException("context == null"); 530 } 531 ensureNotOnMainThread(context); 532 final BlockingQueue<IKeyChainService> q = new LinkedBlockingQueue<IKeyChainService>(1); 533 ServiceConnection keyChainServiceConnection = new ServiceConnection() { 534 volatile boolean mConnectedAtLeastOnce = false; 535 @Override public void onServiceConnected(ComponentName name, IBinder service) { 536 if (!mConnectedAtLeastOnce) { 537 mConnectedAtLeastOnce = true; 538 try { 539 q.put(IKeyChainService.Stub.asInterface(service)); 540 } catch (InterruptedException e) { 541 // will never happen, since the queue starts with one available slot 542 } 543 } 544 } 545 @Override public void onServiceDisconnected(ComponentName name) {} 546 }; 547 Intent intent = new Intent(IKeyChainService.class.getName()); 548 ComponentName comp = intent.resolveSystemService(context.getPackageManager(), 0); 549 intent.setComponent(comp); 550 boolean isBound = context.bindServiceAsUser(intent, 551 keyChainServiceConnection, 552 Context.BIND_AUTO_CREATE, 553 user); 554 if (!isBound) { 555 throw new AssertionError("could not bind to KeyChainService"); 556 } 557 return new KeyChainConnection(context, keyChainServiceConnection, q.take()); 558 } 559 560 private static void ensureNotOnMainThread(@NonNull Context context) { 561 Looper looper = Looper.myLooper(); 562 if (looper != null && looper == context.getMainLooper()) { 563 throw new IllegalStateException( 564 "calling this from your main thread can lead to deadlock"); 565 } 566 } 567 } 568