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.app.Activity; 19 import android.app.PendingIntent; 20 import android.content.ComponentName; 21 import android.content.Context; 22 import android.content.Intent; 23 import android.content.ServiceConnection; 24 import android.os.IBinder; 25 import android.os.Looper; 26 import android.os.RemoteException; 27 import java.io.ByteArrayInputStream; 28 import java.io.Closeable; 29 import java.io.IOException; 30 import java.security.KeyPair; 31 import java.security.Principal; 32 import java.security.PrivateKey; 33 import java.security.cert.Certificate; 34 import java.security.cert.CertificateException; 35 import java.security.cert.CertificateFactory; 36 import java.security.cert.X509Certificate; 37 import java.util.ArrayList; 38 import java.util.List; 39 import java.util.concurrent.BlockingQueue; 40 import java.util.concurrent.LinkedBlockingQueue; 41 import libcore.util.Objects; 42 import org.apache.harmony.xnet.provider.jsse.TrustedCertificateStore; 43 44 /** 45 * The {@code KeyChain} class provides access to private keys and 46 * their corresponding certificate chains in credential storage. 47 * 48 * <p>Applications accessing the {@code KeyChain} normally go through 49 * these steps: 50 * 51 * <ol> 52 * 53 * <li>Receive a callback from an {@link javax.net.ssl.X509KeyManager 54 * X509KeyManager} that a private key is requested. 55 * 56 * <li>Call {@link #choosePrivateKeyAlias 57 * choosePrivateKeyAlias} to allow the user to select from a 58 * list of currently available private keys and corresponding 59 * certificate chains. The chosen alias will be returned by the 60 * callback {@link KeyChainAliasCallback#alias}, or null if no private 61 * key is available or the user cancels the request. 62 * 63 * <li>Call {@link #getPrivateKey} and {@link #getCertificateChain} to 64 * retrieve the credentials to return to the corresponding {@link 65 * javax.net.ssl.X509KeyManager} callbacks. 66 * 67 * </ol> 68 * 69 * <p>An application may remember the value of a selected alias to 70 * avoid prompting the user with {@link #choosePrivateKeyAlias 71 * choosePrivateKeyAlias} on subsequent connections. If the alias is 72 * no longer valid, null will be returned on lookups using that value 73 * 74 * <p>An application can request the installation of private keys and 75 * certificates via the {@code Intent} provided by {@link 76 * #createInstallIntent}. Private keys installed via this {@code 77 * Intent} will be accessible via {@link #choosePrivateKeyAlias} while 78 * Certificate Authority (CA) certificates will be trusted by all 79 * applications through the default {@code X509TrustManager}. 80 */ 81 // TODO reference intent for credential installation when public 82 public final class KeyChain { 83 84 private static final String TAG = "KeyChain"; 85 86 /** 87 * @hide Also used by KeyChainService implementation 88 */ 89 public static final String ACCOUNT_TYPE = "com.android.keychain"; 90 91 /** 92 * Action to bring up the KeyChainActivity 93 */ 94 private static final String ACTION_CHOOSER = "com.android.keychain.CHOOSER"; 95 96 /** 97 * Extra for use with {@link #ACTION_CHOOSER} 98 * @hide Also used by KeyChainActivity implementation 99 */ 100 public static final String EXTRA_RESPONSE = "response"; 101 102 /** 103 * Extra for use with {@link #ACTION_CHOOSER} 104 * @hide Also used by KeyChainActivity implementation 105 */ 106 public static final String EXTRA_HOST = "host"; 107 108 /** 109 * Extra for use with {@link #ACTION_CHOOSER} 110 * @hide Also used by KeyChainActivity implementation 111 */ 112 public static final String EXTRA_PORT = "port"; 113 114 /** 115 * Extra for use with {@link #ACTION_CHOOSER} 116 * @hide Also used by KeyChainActivity implementation 117 */ 118 public static final String EXTRA_ALIAS = "alias"; 119 120 /** 121 * Extra for use with {@link #ACTION_CHOOSER} 122 * @hide Also used by KeyChainActivity implementation 123 */ 124 public static final String EXTRA_SENDER = "sender"; 125 126 /** 127 * Action to bring up the CertInstaller 128 */ 129 private static final String ACTION_INSTALL = "android.credentials.INSTALL"; 130 131 /** 132 * Optional extra to specify a {@code String} credential name on 133 * the {@code Intent} returned by {@link #createInstallIntent}. 134 */ 135 // Compatible with old com.android.certinstaller.CredentialHelper.CERT_NAME_KEY 136 public static final String EXTRA_NAME = "name"; 137 138 /** 139 * Optional extra to specify an X.509 certificate to install on 140 * the {@code Intent} returned by {@link #createInstallIntent}. 141 * The extra value should be a PEM or ASN.1 DER encoded {@code 142 * byte[]}. An {@link X509Certificate} can be converted to DER 143 * encoded bytes with {@link X509Certificate#getEncoded}. 144 * 145 * <p>{@link #EXTRA_NAME} may be used to provide a default alias 146 * name for the installed certificate. 147 */ 148 // Compatible with old android.security.Credentials.CERTIFICATE 149 public static final String EXTRA_CERTIFICATE = "CERT"; 150 151 /** 152 * Optional extra for use with the {@code Intent} returned by 153 * {@link #createInstallIntent} to specify a PKCS#12 key store to 154 * install. The extra value should be a {@code byte[]}. The bytes 155 * may come from an external source or be generated with {@link 156 * java.security.KeyStore#store} on a "PKCS12" instance. 157 * 158 * <p>The user will be prompted for the password to load the key store. 159 * 160 * <p>The key store will be scanned for {@link 161 * java.security.KeyStore.PrivateKeyEntry} entries and both the 162 * private key and associated certificate chain will be installed. 163 * 164 * <p>{@link #EXTRA_NAME} may be used to provide a default alias 165 * name for the installed credentials. 166 */ 167 // Compatible with old android.security.Credentials.PKCS12 168 public static final String EXTRA_PKCS12 = "PKCS12"; 169 170 /** 171 * Returns an {@code Intent} that can be used for credential 172 * installation. The intent may be used without any extras, in 173 * which case the user will be able to install credentials from 174 * their own source. 175 * 176 * <p>Alternatively, {@link #EXTRA_CERTIFICATE} or {@link 177 * #EXTRA_PKCS12} maybe used to specify the bytes of an X.509 178 * certificate or a PKCS#12 key store for installation. These 179 * extras may be combined with {@link #EXTRA_NAME} to provide a 180 * default alias name for credentials being installed. 181 * 182 * <p>When used with {@link Activity#startActivityForResult}, 183 * {@link Activity#RESULT_OK} will be returned if a credential was 184 * successfully installed, otherwise {@link 185 * Activity#RESULT_CANCELED} will be returned. 186 */ 187 public static Intent createInstallIntent() { 188 Intent intent = new Intent(ACTION_INSTALL); 189 intent.setClassName("com.android.certinstaller", 190 "com.android.certinstaller.CertInstallerMain"); 191 return intent; 192 } 193 194 /** 195 * Launches an {@code Activity} for the user to select the alias 196 * for a private key and certificate pair for authentication. The 197 * selected alias or null will be returned via the 198 * KeyChainAliasCallback callback. 199 * 200 * <p>{@code keyTypes} and {@code issuers} may be used to 201 * highlight suggested choices to the user, although to cope with 202 * sometimes erroneous values provided by servers, the user may be 203 * able to override these suggestions. 204 * 205 * <p>{@code host} and {@code port} may be used to give the user 206 * more context about the server requesting the credentials. 207 * 208 * <p>{@code alias} allows the chooser to preselect an existing 209 * alias which will still be subject to user confirmation. 210 * 211 * <p>This method requires the caller to hold the permission 212 * {@link android.Manifest.permission#USE_CREDENTIALS}. 213 * 214 * @param activity The {@link Activity} context to use for 215 * launching the new sub-Activity to prompt the user to select 216 * a private key; used only to call startActivity(); must not 217 * be null. 218 * @param response Callback to invoke when the request completes; 219 * must not be null 220 * @param keyTypes The acceptable types of asymmetric keys such as 221 * "RSA" or "DSA", or a null array. 222 * @param issuers The acceptable certificate issuers for the 223 * certificate matching the private key, or null. 224 * @param host The host name of the server requesting the 225 * certificate, or null if unavailable. 226 * @param port The port number of the server requesting the 227 * certificate, or -1 if unavailable. 228 * @param alias The alias to preselect if available, or null if 229 * unavailable. 230 */ 231 public static void choosePrivateKeyAlias(Activity activity, KeyChainAliasCallback response, 232 String[] keyTypes, Principal[] issuers, 233 String host, int port, 234 String alias) { 235 /* 236 * TODO currently keyTypes, issuers are unused. They are meant 237 * to follow the semantics and purpose of X509KeyManager 238 * method arguments. 239 * 240 * keyTypes would allow the list to be filtered and typically 241 * will be set correctly by the server. In practice today, 242 * most all users will want only RSA, rarely DSA, and usually 243 * only a small number of certs will be available. 244 * 245 * issuers is typically not useful. Some servers historically 246 * will send the entire list of public CAs known to the 247 * server. Others will send none. If this is used, if there 248 * are no matches after applying the constraint, it should be 249 * ignored. 250 */ 251 if (activity == null) { 252 throw new NullPointerException("activity == null"); 253 } 254 if (response == null) { 255 throw new NullPointerException("response == null"); 256 } 257 Intent intent = new Intent(ACTION_CHOOSER); 258 intent.putExtra(EXTRA_RESPONSE, new AliasResponse(response)); 259 intent.putExtra(EXTRA_HOST, host); 260 intent.putExtra(EXTRA_PORT, port); 261 intent.putExtra(EXTRA_ALIAS, alias); 262 // the PendingIntent is used to get calling package name 263 intent.putExtra(EXTRA_SENDER, PendingIntent.getActivity(activity, 0, new Intent(), 0)); 264 activity.startActivity(intent); 265 } 266 267 private static class AliasResponse extends IKeyChainAliasCallback.Stub { 268 private final KeyChainAliasCallback keyChainAliasResponse; 269 private AliasResponse(KeyChainAliasCallback keyChainAliasResponse) { 270 this.keyChainAliasResponse = keyChainAliasResponse; 271 } 272 @Override public void alias(String alias) { 273 keyChainAliasResponse.alias(alias); 274 } 275 } 276 277 /** 278 * Returns the {@code PrivateKey} for the requested alias, or null 279 * if no there is no result. 280 * 281 * <p>This method requires the caller to hold the permission 282 * {@link android.Manifest.permission#USE_CREDENTIALS}. 283 * 284 * @param alias The alias of the desired private key, typically 285 * returned via {@link KeyChainAliasCallback#alias}. 286 * @throws KeyChainException if the alias was valid but there was some problem accessing it. 287 */ 288 public static PrivateKey getPrivateKey(Context context, String alias) 289 throws KeyChainException, InterruptedException { 290 if (alias == null) { 291 throw new NullPointerException("alias == null"); 292 } 293 KeyChainConnection keyChainConnection = bind(context); 294 try { 295 IKeyChainService keyChainService = keyChainConnection.getService(); 296 byte[] privateKeyBytes = keyChainService.getPrivateKey(alias); 297 return toPrivateKey(privateKeyBytes); 298 } catch (RemoteException e) { 299 throw new KeyChainException(e); 300 } catch (RuntimeException e) { 301 // only certain RuntimeExceptions can be propagated across the IKeyChainService call 302 throw new KeyChainException(e); 303 } finally { 304 keyChainConnection.close(); 305 } 306 } 307 308 /** 309 * Returns the {@code X509Certificate} chain for the requested 310 * alias, or null if no there is no result. 311 * 312 * <p>This method requires the caller to hold the permission 313 * {@link android.Manifest.permission#USE_CREDENTIALS}. 314 * 315 * @param alias The alias of the desired certificate chain, typically 316 * returned via {@link KeyChainAliasCallback#alias}. 317 * @throws KeyChainException if the alias was valid but there was some problem accessing it. 318 */ 319 public static X509Certificate[] getCertificateChain(Context context, String alias) 320 throws KeyChainException, InterruptedException { 321 if (alias == null) { 322 throw new NullPointerException("alias == null"); 323 } 324 KeyChainConnection keyChainConnection = bind(context); 325 try { 326 IKeyChainService keyChainService = keyChainConnection.getService(); 327 byte[] certificateBytes = keyChainService.getCertificate(alias); 328 List<X509Certificate> chain = new ArrayList<X509Certificate>(); 329 chain.add(toCertificate(certificateBytes)); 330 TrustedCertificateStore store = new TrustedCertificateStore(); 331 for (int i = 0; true; i++) { 332 X509Certificate cert = chain.get(i); 333 if (Objects.equal(cert.getSubjectX500Principal(), cert.getIssuerX500Principal())) { 334 break; 335 } 336 X509Certificate issuer = store.findIssuer(cert); 337 if (issuer == null) { 338 break; 339 } 340 chain.add(issuer); 341 } 342 return chain.toArray(new X509Certificate[chain.size()]); 343 } catch (RemoteException e) { 344 throw new KeyChainException(e); 345 } catch (RuntimeException e) { 346 // only certain RuntimeExceptions can be propagated across the IKeyChainService call 347 throw new KeyChainException(e); 348 } finally { 349 keyChainConnection.close(); 350 } 351 } 352 353 private static PrivateKey toPrivateKey(byte[] bytes) { 354 if (bytes == null) { 355 throw new IllegalArgumentException("bytes == null"); 356 } 357 try { 358 KeyPair keyPair = (KeyPair) Credentials.convertFromPem(bytes).get(0); 359 return keyPair.getPrivate(); 360 } catch (IOException e) { 361 throw new AssertionError(e); 362 } 363 } 364 365 private static X509Certificate toCertificate(byte[] bytes) { 366 if (bytes == null) { 367 throw new IllegalArgumentException("bytes == null"); 368 } 369 try { 370 CertificateFactory certFactory = CertificateFactory.getInstance("X.509"); 371 Certificate cert = certFactory.generateCertificate(new ByteArrayInputStream(bytes)); 372 return (X509Certificate) cert; 373 } catch (CertificateException e) { 374 throw new AssertionError(e); 375 } 376 } 377 378 /** 379 * @hide for reuse by CertInstaller and Settings. 380 * @see KeyChain#bind 381 */ 382 public final static class KeyChainConnection implements Closeable { 383 private final Context context; 384 private final ServiceConnection serviceConnection; 385 private final IKeyChainService service; 386 private KeyChainConnection(Context context, 387 ServiceConnection serviceConnection, 388 IKeyChainService service) { 389 this.context = context; 390 this.serviceConnection = serviceConnection; 391 this.service = service; 392 } 393 @Override public void close() { 394 context.unbindService(serviceConnection); 395 } 396 public IKeyChainService getService() { 397 return service; 398 } 399 } 400 401 /** 402 * @hide for reuse by CertInstaller and Settings. 403 * 404 * Caller should call unbindService on the result when finished. 405 */ 406 public static KeyChainConnection bind(Context context) throws InterruptedException { 407 if (context == null) { 408 throw new NullPointerException("context == null"); 409 } 410 ensureNotOnMainThread(context); 411 final BlockingQueue<IKeyChainService> q = new LinkedBlockingQueue<IKeyChainService>(1); 412 ServiceConnection keyChainServiceConnection = new ServiceConnection() { 413 volatile boolean mConnectedAtLeastOnce = false; 414 @Override public void onServiceConnected(ComponentName name, IBinder service) { 415 if (!mConnectedAtLeastOnce) { 416 mConnectedAtLeastOnce = true; 417 try { 418 q.put(IKeyChainService.Stub.asInterface(service)); 419 } catch (InterruptedException e) { 420 // will never happen, since the queue starts with one available slot 421 } 422 } 423 } 424 @Override public void onServiceDisconnected(ComponentName name) {} 425 }; 426 boolean isBound = context.bindService(new Intent(IKeyChainService.class.getName()), 427 keyChainServiceConnection, 428 Context.BIND_AUTO_CREATE); 429 if (!isBound) { 430 throw new AssertionError("could not bind to KeyChainService"); 431 } 432 return new KeyChainConnection(context, keyChainServiceConnection, q.take()); 433 } 434 435 private static void ensureNotOnMainThread(Context context) { 436 Looper looper = Looper.myLooper(); 437 if (looper != null && looper == context.getMainLooper()) { 438 throw new IllegalStateException( 439 "calling this from your main thread can lead to deadlock"); 440 } 441 } 442 } 443
