LockPatternUtils.java revision d47c6ed4a9f2b5bd31f6c806b74701428efe458b
1/* 2 * Copyright (C) 2007 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 com.android.internal.widget; 18 19import android.app.DevicePolicyManager; 20import android.content.ComponentName; 21import android.content.ContentResolver; 22import android.content.Context; 23import android.os.SystemClock; 24import android.provider.Settings; 25import android.security.MessageDigest; 26import android.text.TextUtils; 27import android.util.Log; 28 29import com.google.android.collect.Lists; 30 31import java.io.FileNotFoundException; 32import java.io.IOException; 33import java.io.RandomAccessFile; 34import java.security.NoSuchAlgorithmException; 35import java.security.SecureRandom; 36import java.util.Arrays; 37import java.util.List; 38 39/** 40 * Utilities for the lock patten and its settings. 41 */ 42public class LockPatternUtils { 43 44 private static final String TAG = "LockPatternUtils"; 45 46 private static final String LOCK_PATTERN_FILE = "/system/gesture.key"; 47 private static final String LOCK_PASSWORD_FILE = "/system/password.key"; 48 49 /** 50 * The maximum number of incorrect attempts before the user is prevented 51 * from trying again for {@link #FAILED_ATTEMPT_TIMEOUT_MS}. 52 */ 53 public static final int FAILED_ATTEMPTS_BEFORE_TIMEOUT = 5; 54 55 /** 56 * The number of incorrect attempts before which we fall back on an alternative 57 * method of verifying the user, and resetting their lock pattern. 58 */ 59 public static final int FAILED_ATTEMPTS_BEFORE_RESET = 20; 60 61 /** 62 * How long the user is prevented from trying again after entering the 63 * wrong pattern too many times. 64 */ 65 public static final long FAILED_ATTEMPT_TIMEOUT_MS = 30000L; 66 67 /** 68 * The interval of the countdown for showing progress of the lockout. 69 */ 70 public static final long FAILED_ATTEMPT_COUNTDOWN_INTERVAL_MS = 1000L; 71 72 /** 73 * The minimum number of dots in a valid pattern. 74 */ 75 public static final int MIN_LOCK_PATTERN_SIZE = 4; 76 77 /** 78 * Type of password being stored. 79 * pattern = pattern screen 80 * pin = digit-only password 81 * password = alphanumeric password 82 */ 83 public static final int MODE_PATTERN = DevicePolicyManager.PASSWORD_MODE_SOMETHING; 84 public static final int MODE_PIN = DevicePolicyManager.PASSWORD_MODE_NUMERIC; 85 public static final int MODE_PASSWORD = DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC; 86 87 /** 88 * The minimum number of dots the user must include in a wrong pattern 89 * attempt for it to be counted against the counts that affect 90 * {@link #FAILED_ATTEMPTS_BEFORE_TIMEOUT} and {@link #FAILED_ATTEMPTS_BEFORE_RESET} 91 */ 92 public static final int MIN_PATTERN_REGISTER_FAIL = 3; 93 94 private final static String LOCKOUT_PERMANENT_KEY = "lockscreen.lockedoutpermanently"; 95 private final static String LOCKOUT_ATTEMPT_DEADLINE = "lockscreen.lockoutattemptdeadline"; 96 private final static String PATTERN_EVER_CHOSEN_KEY = "lockscreen.patterneverchosen"; 97 public final static String PASSWORD_TYPE_KEY = "lockscreen.password_type"; 98 private final static String LOCK_PASSWORD_SALT_KEY = "lockscreen.password_salt"; 99 100 private final Context mContext; 101 private final ContentResolver mContentResolver; 102 private DevicePolicyManager mDevicePolicyManager; 103 private static String sLockPatternFilename; 104 private static String sLockPasswordFilename; 105 106 /** 107 * @param contentResolver Used to look up and save settings. 108 */ 109 public LockPatternUtils(Context context) { 110 mContext = context; 111 mContentResolver = context.getContentResolver(); 112 mDevicePolicyManager = 113 (DevicePolicyManager)context.getSystemService(Context.DEVICE_POLICY_SERVICE); 114 // Initialize the location of gesture lock file 115 if (sLockPatternFilename == null) { 116 sLockPatternFilename = android.os.Environment.getDataDirectory() 117 .getAbsolutePath() + LOCK_PATTERN_FILE; 118 sLockPasswordFilename = android.os.Environment.getDataDirectory() 119 .getAbsolutePath() + LOCK_PASSWORD_FILE; 120 } 121 122 } 123 124 public int getRequestedMinimumPasswordLength() { 125 return mDevicePolicyManager.getMinimumPasswordLength(); 126 } 127 128 /** 129 * Gets the device policy password mode. If the mode is non-specific, returns 130 * MODE_PATTERN which allows the user to choose anything. 131 * 132 * @return 133 */ 134 public int getRequestedPasswordMode() { 135 int policyMode = mDevicePolicyManager.getPasswordMode(); 136 switch (policyMode) { 137 case DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC: 138 return MODE_PASSWORD; 139 case DevicePolicyManager.PASSWORD_MODE_NUMERIC: 140 return MODE_PIN; 141 case DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED: 142 return MODE_PATTERN; 143 } 144 return MODE_PATTERN; 145 } 146 147 /** 148 * Returns the actual password mode, as set by keyguard after updating the password. 149 * 150 * @return 151 */ 152 public void reportFailedPasswordAttempt() { 153 mDevicePolicyManager.reportFailedPasswordAttempt(); 154 } 155 156 public void reportSuccessfulPasswordAttempt() { 157 mDevicePolicyManager.reportSuccessfulPasswordAttempt(); 158 } 159 160 public void setActivePasswordState(int mode, int length) { 161 int policyMode = DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED; 162 switch (mode) { 163 case MODE_PATTERN: 164 policyMode = DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED; 165 break; 166 case MODE_PIN: 167 policyMode = DevicePolicyManager.PASSWORD_MODE_NUMERIC; 168 break; 169 case MODE_PASSWORD: 170 policyMode = DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC; 171 break; 172 } 173 mDevicePolicyManager.setActivePasswordState(policyMode, length); 174 } 175 176 /** 177 * Check to see if a pattern matches the saved pattern. If no pattern exists, 178 * always returns true. 179 * @param pattern The pattern to check. 180 * @return Whether the pattern matches the stored one. 181 */ 182 public boolean checkPattern(List<LockPatternView.Cell> pattern) { 183 try { 184 // Read all the bytes from the file 185 RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "r"); 186 final byte[] stored = new byte[(int) raf.length()]; 187 int got = raf.read(stored, 0, stored.length); 188 raf.close(); 189 if (got <= 0) { 190 return true; 191 } 192 // Compare the hash from the file with the entered pattern's hash 193 return Arrays.equals(stored, LockPatternUtils.patternToHash(pattern)); 194 } catch (FileNotFoundException fnfe) { 195 return true; 196 } catch (IOException ioe) { 197 return true; 198 } 199 } 200 201 /** 202 * Check to see if a password matches the saved password. If no password exists, 203 * always returns true. 204 * @param password The password to check. 205 * @return Whether the password matches the stored one. 206 */ 207 public boolean checkPassword(String password) { 208 try { 209 // Read all the bytes from the file 210 RandomAccessFile raf = new RandomAccessFile(sLockPasswordFilename, "r"); 211 final byte[] stored = new byte[(int) raf.length()]; 212 int got = raf.read(stored, 0, stored.length); 213 raf.close(); 214 if (got <= 0) { 215 return true; 216 } 217 // Compare the hash from the file with the entered password's hash 218 return Arrays.equals(stored, passwordToHash(password)); 219 } catch (FileNotFoundException fnfe) { 220 return true; 221 } catch (IOException ioe) { 222 return true; 223 } 224 } 225 226 /** 227 * Checks to see if the given file exists and contains any data. Returns true if it does, 228 * false otherwise. 229 * @param filename 230 * @return true if file exists and is non-empty. 231 */ 232 private boolean nonEmptyFileExists(String filename) { 233 try { 234 // Check if we can read a byte from the file 235 RandomAccessFile raf = new RandomAccessFile(filename, "r"); 236 byte first = raf.readByte(); 237 raf.close(); 238 return true; 239 } catch (FileNotFoundException fnfe) { 240 return false; 241 } catch (IOException ioe) { 242 return false; 243 } 244 } 245 246 /** 247 * Check to see if the user has stored a lock pattern. 248 * @return Whether a saved pattern exists. 249 */ 250 public boolean savedPatternExists() { 251 return nonEmptyFileExists(sLockPatternFilename); 252 } 253 254 /** 255 * Check to see if the user has stored a lock pattern. 256 * @return Whether a saved pattern exists. 257 */ 258 public boolean savedPasswordExists() { 259 return nonEmptyFileExists(sLockPasswordFilename); 260 } 261 262 /** 263 * Return true if the user has ever chosen a pattern. This is true even if the pattern is 264 * currently cleared. 265 * 266 * @return True if the user has ever chosen a pattern. 267 */ 268 public boolean isPatternEverChosen() { 269 return getBoolean(PATTERN_EVER_CHOSEN_KEY); 270 } 271 272 /** 273 * Clear any lock pattern or password. 274 */ 275 public void clearLock() { 276 saveLockPassword(null, LockPatternUtils.MODE_PATTERN); 277 setLockPatternEnabled(false); 278 saveLockPattern(null); 279 setLong(PASSWORD_TYPE_KEY, MODE_PATTERN); 280 } 281 282 /** 283 * Save a lock pattern. 284 * @param pattern The new pattern to save. 285 */ 286 public void saveLockPattern(List<LockPatternView.Cell> pattern) { 287 // Compute the hash 288 final byte[] hash = LockPatternUtils.patternToHash(pattern); 289 try { 290 // Write the hash to file 291 RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "rw"); 292 // Truncate the file if pattern is null, to clear the lock 293 if (pattern == null) { 294 raf.setLength(0); 295 } else { 296 raf.write(hash, 0, hash.length); 297 } 298 raf.close(); 299 if (pattern != null) { 300 setBoolean(PATTERN_EVER_CHOSEN_KEY, true); 301 setLong(PASSWORD_TYPE_KEY, MODE_PATTERN); 302 DevicePolicyManager dpm = (DevicePolicyManager)mContext.getSystemService( 303 Context.DEVICE_POLICY_SERVICE); 304 dpm.setActivePasswordState( 305 DevicePolicyManager.PASSWORD_MODE_SOMETHING, pattern.size()); 306 } 307 } catch (FileNotFoundException fnfe) { 308 // Cant do much, unless we want to fail over to using the settings provider 309 Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename); 310 } catch (IOException ioe) { 311 // Cant do much 312 Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename); 313 } 314 } 315 316 /** 317 * Save a lock password. 318 * @param password The password to save 319 */ 320 public void saveLockPassword(String password, int mode) { 321 // Compute the hash 322 final byte[] hash = passwordToHash(password); 323 try { 324 // Write the hash to file 325 RandomAccessFile raf = new RandomAccessFile(sLockPasswordFilename, "rw"); 326 // Truncate the file if pattern is null, to clear the lock 327 if (password == null) { 328 raf.setLength(0); 329 } else { 330 raf.write(hash, 0, hash.length); 331 } 332 raf.close(); 333 if (password != null) { 334 int textMode = TextUtils.isDigitsOnly(password) ? MODE_PIN : MODE_PASSWORD; 335 if (textMode > mode) { 336 mode = textMode; 337 } 338 setLong(PASSWORD_TYPE_KEY, mode); 339 DevicePolicyManager dpm = (DevicePolicyManager)mContext.getSystemService( 340 Context.DEVICE_POLICY_SERVICE); 341 dpm.setActivePasswordState(mode, password.length()); 342 } 343 } catch (FileNotFoundException fnfe) { 344 // Cant do much, unless we want to fail over to using the settings provider 345 Log.e(TAG, "Unable to save lock pattern to " + sLockPasswordFilename); 346 } catch (IOException ioe) { 347 // Cant do much 348 Log.e(TAG, "Unable to save lock pattern to " + sLockPasswordFilename); 349 } 350 } 351 352 public int getPasswordMode() { 353 return (int) getLong(PASSWORD_TYPE_KEY, MODE_PATTERN); 354 } 355 356 /** 357 * Deserialize a pattern. 358 * @param string The pattern serialized with {@link #patternToString} 359 * @return The pattern. 360 */ 361 public static List<LockPatternView.Cell> stringToPattern(String string) { 362 List<LockPatternView.Cell> result = Lists.newArrayList(); 363 364 final byte[] bytes = string.getBytes(); 365 for (int i = 0; i < bytes.length; i++) { 366 byte b = bytes[i]; 367 result.add(LockPatternView.Cell.of(b / 3, b % 3)); 368 } 369 return result; 370 } 371 372 /** 373 * Serialize a pattern. 374 * @param pattern The pattern. 375 * @return The pattern in string form. 376 */ 377 public static String patternToString(List<LockPatternView.Cell> pattern) { 378 if (pattern == null) { 379 return ""; 380 } 381 final int patternSize = pattern.size(); 382 383 byte[] res = new byte[patternSize]; 384 for (int i = 0; i < patternSize; i++) { 385 LockPatternView.Cell cell = pattern.get(i); 386 res[i] = (byte) (cell.getRow() * 3 + cell.getColumn()); 387 } 388 return new String(res); 389 } 390 391 /* 392 * Generate an SHA-1 hash for the pattern. Not the most secure, but it is 393 * at least a second level of protection. First level is that the file 394 * is in a location only readable by the system process. 395 * @param pattern the gesture pattern. 396 * @return the hash of the pattern in a byte array. 397 */ 398 private static byte[] patternToHash(List<LockPatternView.Cell> pattern) { 399 if (pattern == null) { 400 return null; 401 } 402 403 final int patternSize = pattern.size(); 404 byte[] res = new byte[patternSize]; 405 for (int i = 0; i < patternSize; i++) { 406 LockPatternView.Cell cell = pattern.get(i); 407 res[i] = (byte) (cell.getRow() * 3 + cell.getColumn()); 408 } 409 try { 410 MessageDigest md = MessageDigest.getInstance("SHA-1"); 411 byte[] hash = md.digest(res); 412 return hash; 413 } catch (NoSuchAlgorithmException nsa) { 414 return res; 415 } 416 } 417 418 private String getSalt() { 419 long salt = getLong(LOCK_PASSWORD_SALT_KEY, 0); 420 if (salt == 0) { 421 try { 422 salt = SecureRandom.getInstance("SHA1PRNG").nextLong(); 423 setLong(LOCK_PASSWORD_SALT_KEY, salt); 424 Log.v(TAG, "Initialized lock password salt"); 425 } catch (NoSuchAlgorithmException e) { 426 // Throw an exception rather than storing a password we'll never be able to recover 427 throw new IllegalStateException("Couldn't get SecureRandom number", e); 428 } 429 } 430 return Long.toHexString(salt); 431 } 432 433 /* 434 * Generate a hash for the given password. To avoid brute force attacks, we use a salted hash. 435 * Not the most secure, but it is at least a second level of protection. First level is that 436 * the file is in a location only readable by the system process. 437 * @param password the gesture pattern. 438 * @return the hash of the pattern in a byte array. 439 */ 440 public byte[] passwordToHash(String password) { 441 if (password == null) { 442 return null; 443 } 444 String algo = null; 445 byte[] hashed = null; 446 try { 447 byte[] saltedPassword = (password + getSalt()).getBytes(); 448 byte[] sha1 = MessageDigest.getInstance(algo = "SHA-1").digest(saltedPassword); 449 byte[] md5 = MessageDigest.getInstance(algo = "MD5").digest(saltedPassword); 450 hashed = (toHex(sha1) + toHex(md5)).getBytes(); 451 } catch (NoSuchAlgorithmException e) { 452 Log.w(TAG, "Failed to encode string because of missing algorithm: " + algo); 453 } 454 return hashed; 455 } 456 457 private static String toHex(byte[] ary) { 458 final String hex = "0123456789ABCDEF"; 459 String ret = ""; 460 for (int i = 0; i < ary.length; i++) { 461 ret += hex.charAt((ary[i] >> 4) & 0xf); 462 ret += hex.charAt(ary[i] & 0xf); 463 } 464 return ret; 465 } 466 467 /** 468 * @return Whether the lock password is enabled. 469 */ 470 public boolean isLockPasswordEnabled() { 471 long mode = getLong(PASSWORD_TYPE_KEY, 0); 472 return savedPasswordExists() && (mode == MODE_PASSWORD || mode == MODE_PIN); 473 } 474 475 /** 476 * @return Whether the lock pattern is enabled. 477 */ 478 public boolean isLockPatternEnabled() { 479 return getBoolean(Settings.System.LOCK_PATTERN_ENABLED) 480 && getLong(PASSWORD_TYPE_KEY, MODE_PATTERN) == MODE_PATTERN; 481 } 482 483 /** 484 * Set whether the lock pattern is enabled. 485 */ 486 public void setLockPatternEnabled(boolean enabled) { 487 setBoolean(Settings.System.LOCK_PATTERN_ENABLED, enabled); 488 } 489 490 /** 491 * @return Whether the visible pattern is enabled. 492 */ 493 public boolean isVisiblePatternEnabled() { 494 return getBoolean(Settings.System.LOCK_PATTERN_VISIBLE); 495 } 496 497 /** 498 * Set whether the visible pattern is enabled. 499 */ 500 public void setVisiblePatternEnabled(boolean enabled) { 501 setBoolean(Settings.System.LOCK_PATTERN_VISIBLE, enabled); 502 } 503 504 /** 505 * @return Whether tactile feedback for the pattern is enabled. 506 */ 507 public boolean isTactileFeedbackEnabled() { 508 return getBoolean(Settings.System.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED); 509 } 510 511 /** 512 * Set whether tactile feedback for the pattern is enabled. 513 */ 514 public void setTactileFeedbackEnabled(boolean enabled) { 515 setBoolean(Settings.System.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED, enabled); 516 } 517 518 /** 519 * Set and store the lockout deadline, meaning the user can't attempt his/her unlock 520 * pattern until the deadline has passed. 521 * @return the chosen deadline. 522 */ 523 public long setLockoutAttemptDeadline() { 524 final long deadline = SystemClock.elapsedRealtime() + FAILED_ATTEMPT_TIMEOUT_MS; 525 setLong(LOCKOUT_ATTEMPT_DEADLINE, deadline); 526 return deadline; 527 } 528 529 /** 530 * @return The elapsed time in millis in the future when the user is allowed to 531 * attempt to enter his/her lock pattern, or 0 if the user is welcome to 532 * enter a pattern. 533 */ 534 public long getLockoutAttemptDeadline() { 535 final long deadline = getLong(LOCKOUT_ATTEMPT_DEADLINE, 0L); 536 final long now = SystemClock.elapsedRealtime(); 537 if (deadline < now || deadline > (now + FAILED_ATTEMPT_TIMEOUT_MS)) { 538 return 0L; 539 } 540 return deadline; 541 } 542 543 /** 544 * @return Whether the user is permanently locked out until they verify their 545 * credentials. Occurs after {@link #FAILED_ATTEMPTS_BEFORE_RESET} failed 546 * attempts. 547 */ 548 public boolean isPermanentlyLocked() { 549 return getBoolean(LOCKOUT_PERMANENT_KEY); 550 } 551 552 /** 553 * Set the state of whether the device is permanently locked, meaning the user 554 * must authenticate via other means. 555 * 556 * @param locked Whether the user is permanently locked out until they verify their 557 * credentials. Occurs after {@link #FAILED_ATTEMPTS_BEFORE_RESET} failed 558 * attempts. 559 */ 560 public void setPermanentlyLocked(boolean locked) { 561 setBoolean(LOCKOUT_PERMANENT_KEY, locked); 562 } 563 564 /** 565 * @return A formatted string of the next alarm (for showing on the lock screen), 566 * or null if there is no next alarm. 567 */ 568 public String getNextAlarm() { 569 String nextAlarm = Settings.System.getString(mContentResolver, 570 Settings.System.NEXT_ALARM_FORMATTED); 571 if (nextAlarm == null || TextUtils.isEmpty(nextAlarm)) { 572 return null; 573 } 574 return nextAlarm; 575 } 576 577 private boolean getBoolean(String systemSettingKey) { 578 // STOPSHIP: these need to be moved to secure settings! 579 return 1 == 580 android.provider.Settings.System.getInt( 581 mContentResolver, 582 systemSettingKey, 0); 583 } 584 585 private void setBoolean(String systemSettingKey, boolean enabled) { 586 // STOPSHIP: these need to be moved to secure settings! 587 android.provider.Settings.System.putInt( 588 mContentResolver, 589 systemSettingKey, 590 enabled ? 1 : 0); 591 } 592 593 private long getLong(String systemSettingKey, long def) { 594 // STOPSHIP: these need to be moved to secure settings! 595 return android.provider.Settings.System.getLong(mContentResolver, systemSettingKey, def); 596 } 597 598 private void setLong(String systemSettingKey, long value) { 599 // STOPSHIP: these need to be moved to secure settings! 600 android.provider.Settings.System.putLong(mContentResolver, systemSettingKey, value); 601 } 602 603 public boolean isSecure() { 604 long mode = getPasswordMode(); 605 boolean secure = mode == MODE_PATTERN && isLockPatternEnabled() && savedPatternExists() 606 || (mode == MODE_PIN || mode == MODE_PASSWORD) && savedPasswordExists(); 607 return secure; 608 } 609} 610