core/java/com/android/internal/widget/LockPatternUtils.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.internal.widget;

 import android.app.DevicePolicyManager;
 import android.content.ComponentName;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.os.SystemClock;
 import android.provider.Settings;
 import android.security.MessageDigest;
 import android.text.TextUtils;
 import android.util.Log;

 import com.google.android.collect.Lists;

 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.util.Arrays;
 import java.util.List;

 /**
  * Utilities for the lock patten and its settings.
  */
 public class LockPatternUtils {

     private static final String TAG = "LockPatternUtils";

     private static final String LOCK_PATTERN_FILE = "/system/gesture.key";
     private static final String LOCK_PASSWORD_FILE = "/system/password.key";

     /**
      * The maximum number of incorrect attempts before the user is prevented
      * from trying again for {@link #FAILED_ATTEMPT_TIMEOUT_MS}.
      */
     public static final int FAILED_ATTEMPTS_BEFORE_TIMEOUT = 5;

     /**
      * The number of incorrect attempts before which we fall back on an alternative
      * method of verifying the user, and resetting their lock pattern.
      */
     public static final int FAILED_ATTEMPTS_BEFORE_RESET = 20;

     /**
      * How long the user is prevented from trying again after entering the
      * wrong pattern too many times.
      */
     public static final long FAILED_ATTEMPT_TIMEOUT_MS = 30000L;

     /**
      * The interval of the countdown for showing progress of the lockout.
      */
     public static final long FAILED_ATTEMPT_COUNTDOWN_INTERVAL_MS = 1000L;

     /**
      * The minimum number of dots in a valid pattern.
      */
     public static final int MIN_LOCK_PATTERN_SIZE = 4;

     /**
      * Type of password being stored.
      * pattern = pattern screen
      * pin = digit-only password
      * password = alphanumeric password
      */
     public static final int MODE_PATTERN = DevicePolicyManager.PASSWORD_MODE_SOMETHING;
     public static final int MODE_PIN = DevicePolicyManager.PASSWORD_MODE_NUMERIC;
     public static final int MODE_PASSWORD = DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC;

     /**
      * The minimum number of dots the user must include in a wrong pattern
      * attempt for it to be counted against the counts that affect
      * {@link #FAILED_ATTEMPTS_BEFORE_TIMEOUT} and {@link #FAILED_ATTEMPTS_BEFORE_RESET}
      */
     public static final int MIN_PATTERN_REGISTER_FAIL = 3;

     private final static String LOCKOUT_PERMANENT_KEY = "lockscreen.lockedoutpermanently";
     private final static String LOCKOUT_ATTEMPT_DEADLINE = "lockscreen.lockoutattemptdeadline";
     private final static String PATTERN_EVER_CHOSEN_KEY = "lockscreen.patterneverchosen";
     public final static String PASSWORD_TYPE_KEY = "lockscreen.password_type";
     private final static String LOCK_PASSWORD_SALT_KEY = "lockscreen.password_salt";

     private final Context mContext;
     private final ContentResolver mContentResolver;
     private DevicePolicyManager mDevicePolicyManager;
     private static String sLockPatternFilename;
     private static String sLockPasswordFilename;

     /**
      * @param contentResolver Used to look up and save settings.
      */
     public LockPatternUtils(Context context) {
         mContext = context;
         mContentResolver = context.getContentResolver();
         mDevicePolicyManager =
                 (DevicePolicyManager)context.getSystemService(Context.DEVICE_POLICY_SERVICE);
         // Initialize the location of gesture lock file
         if (sLockPatternFilename == null) {
             sLockPatternFilename = android.os.Environment.getDataDirectory()
                     .getAbsolutePath() + LOCK_PATTERN_FILE;
             sLockPasswordFilename = android.os.Environment.getDataDirectory()
                     .getAbsolutePath() + LOCK_PASSWORD_FILE;
         }

     }

     public int getRequestedMinimumPasswordLength() {
         return mDevicePolicyManager.getMinimumPasswordLength();
     }

     /**
      * Gets the device policy password mode. If the mode is non-specific, returns
      * MODE_PATTERN which allows the user to choose anything.
      *
      * @return
      */
     public int getRequestedPasswordMode() {
         int policyMode = mDevicePolicyManager.getPasswordMode();
         switch (policyMode) {
             case DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC:
                 return MODE_PASSWORD;
             case DevicePolicyManager.PASSWORD_MODE_NUMERIC:
                 return MODE_PIN;
             case DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED:
                 return MODE_PATTERN;
         }
         return MODE_PATTERN;
     }

     /**
      * Returns the actual password mode, as set by keyguard after updating the password.
      *
      * @return
      */
     public void reportFailedPasswordAttempt() {
         mDevicePolicyManager.reportFailedPasswordAttempt();
     }

     public void reportSuccessfulPasswordAttempt() {
         mDevicePolicyManager.reportSuccessfulPasswordAttempt();
     }

     public void setActivePasswordState(int mode, int length) {
         int policyMode = DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED;
         switch (mode) {
             case MODE_PATTERN:
                 policyMode = DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED;
                 break;
             case MODE_PIN:
                 policyMode = DevicePolicyManager.PASSWORD_MODE_NUMERIC;
                 break;
             case MODE_PASSWORD:
                 policyMode = DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC;
                 break;
         }
         mDevicePolicyManager.setActivePasswordState(policyMode, length);
     }

     /**
      * Check to see if a pattern matches the saved pattern.  If no pattern exists,
      * always returns true.
      * @param pattern The pattern to check.
      * @return Whether the pattern matches the stored one.
      */
     public boolean checkPattern(List<LockPatternView.Cell> pattern) {
         try {
             // Read all the bytes from the file
             RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "r");
             final byte[] stored = new byte[(int) raf.length()];
             int got = raf.read(stored, 0, stored.length);
             raf.close();
             if (got <= 0) {
                 return true;
             }
             // Compare the hash from the file with the entered pattern's hash
             return Arrays.equals(stored, LockPatternUtils.patternToHash(pattern));
         } catch (FileNotFoundException fnfe) {
             return true;
         } catch (IOException ioe) {
             return true;
         }
     }

     /**
      * Check to see if a password matches the saved password.  If no password exists,
      * always returns true.
      * @param password The password to check.
      * @return Whether the password matches the stored one.
      */
     public boolean checkPassword(String password) {
         try {
             // Read all the bytes from the file
             RandomAccessFile raf = new RandomAccessFile(sLockPasswordFilename, "r");
             final byte[] stored = new byte[(int) raf.length()];
             int got = raf.read(stored, 0, stored.length);
             raf.close();
             if (got <= 0) {
                 return true;
             }
             // Compare the hash from the file with the entered password's hash
             return Arrays.equals(stored, passwordToHash(password));
         } catch (FileNotFoundException fnfe) {
             return true;
         } catch (IOException ioe) {
             return true;
         }
     }

     /**
      * Checks to see if the given file exists and contains any data. Returns true if it does,
      * false otherwise.
      * @param filename
      * @return true if file exists and is non-empty.
      */
     private boolean nonEmptyFileExists(String filename) {
         try {
             // Check if we can read a byte from the file
             RandomAccessFile raf = new RandomAccessFile(filename, "r");
             byte first = raf.readByte();
             raf.close();
             return true;
         } catch (FileNotFoundException fnfe) {
             return false;
         } catch (IOException ioe) {
             return false;
         }
     }

     /**
      * Check to see if the user has stored a lock pattern.
      * @return Whether a saved pattern exists.
      */
     public boolean savedPatternExists() {
         return nonEmptyFileExists(sLockPatternFilename);
     }

     /**
      * Check to see if the user has stored a lock pattern.
      * @return Whether a saved pattern exists.
      */
     public boolean savedPasswordExists() {
         return nonEmptyFileExists(sLockPasswordFilename);
     }

     /**
      * Return true if the user has ever chosen a pattern.  This is true even if the pattern is
      * currently cleared.
      *
      * @return True if the user has ever chosen a pattern.
      */
     public boolean isPatternEverChosen() {
         return getBoolean(PATTERN_EVER_CHOSEN_KEY);
     }

     /**
      * Clear any lock pattern or password.
      */
     public void clearLock() {
         saveLockPassword(null, LockPatternUtils.MODE_PATTERN);
         setLockPatternEnabled(false);
         saveLockPattern(null);
         setLong(PASSWORD_TYPE_KEY, MODE_PATTERN);
     }

     /**
      * Save a lock pattern.
      * @param pattern The new pattern to save.
      */
     public void saveLockPattern(List<LockPatternView.Cell> pattern) {
         // Compute the hash
         final byte[] hash  = LockPatternUtils.patternToHash(pattern);
         try {
             // Write the hash to file
             RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "rw");
             // Truncate the file if pattern is null, to clear the lock
             if (pattern == null) {
                 raf.setLength(0);
             } else {
                 raf.write(hash, 0, hash.length);
             }
             raf.close();
             if (pattern != null) {
                 setBoolean(PATTERN_EVER_CHOSEN_KEY, true);
                 setLong(PASSWORD_TYPE_KEY, MODE_PATTERN);
                 DevicePolicyManager dpm = (DevicePolicyManager)mContext.getSystemService(
                         Context.DEVICE_POLICY_SERVICE);
                 dpm.setActivePasswordState(
                         DevicePolicyManager.PASSWORD_MODE_SOMETHING, pattern.size());
             }
         } catch (FileNotFoundException fnfe) {
             // Cant do much, unless we want to fail over to using the settings provider
             Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename);
         } catch (IOException ioe) {
             // Cant do much
             Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename);
         }
     }

     /**
      * Save a lock password.
      * @param password The password to save
      */
     public void saveLockPassword(String password, int mode) {
         // Compute the hash
         final byte[] hash = passwordToHash(password);
         try {
             // Write the hash to file
             RandomAccessFile raf = new RandomAccessFile(sLockPasswordFilename, "rw");
             // Truncate the file if pattern is null, to clear the lock
             if (password == null) {
                 raf.setLength(0);
             } else {
                 raf.write(hash, 0, hash.length);
             }
             raf.close();
             if (password != null) {
                 int textMode = TextUtils.isDigitsOnly(password) ? MODE_PIN : MODE_PASSWORD;
                 if (textMode > mode) {
                     mode = textMode;
                 }
                 setLong(PASSWORD_TYPE_KEY, mode);
                 DevicePolicyManager dpm = (DevicePolicyManager)mContext.getSystemService(
                         Context.DEVICE_POLICY_SERVICE);
                 dpm.setActivePasswordState(mode, password.length());
             }
         } catch (FileNotFoundException fnfe) {
             // Cant do much, unless we want to fail over to using the settings provider
             Log.e(TAG, "Unable to save lock pattern to " + sLockPasswordFilename);
         } catch (IOException ioe) {
             // Cant do much
             Log.e(TAG, "Unable to save lock pattern to " + sLockPasswordFilename);
         }
     }

     public int getPasswordMode() {
         return (int) getLong(PASSWORD_TYPE_KEY, MODE_PATTERN);
     }

     /**
      * Deserialize a pattern.
      * @param string The pattern serialized with {@link #patternToString}
      * @return The pattern.
      */
     public static List<LockPatternView.Cell> stringToPattern(String string) {
         List<LockPatternView.Cell> result = Lists.newArrayList();

         final byte[] bytes = string.getBytes();
         for (int i = 0; i < bytes.length; i++) {
             byte b = bytes[i];
             result.add(LockPatternView.Cell.of(b / 3, b % 3));
         }
         return result;
     }

     /**
      * Serialize a pattern.
      * @param pattern The pattern.
      * @return The pattern in string form.
      */
     public static String patternToString(List<LockPatternView.Cell> pattern) {
         if (pattern == null) {
             return "";
         }
         final int patternSize = pattern.size();

         byte[] res = new byte[patternSize];
         for (int i = 0; i < patternSize; i++) {
             LockPatternView.Cell cell = pattern.get(i);
             res[i] = (byte) (cell.getRow() * 3 + cell.getColumn());
         }
         return new String(res);
     }

     /*
      * Generate an SHA-1 hash for the pattern. Not the most secure, but it is
      * at least a second level of protection. First level is that the file
      * is in a location only readable by the system process.
      * @param pattern the gesture pattern.
      * @return the hash of the pattern in a byte array.
      */
     private static byte[] patternToHash(List<LockPatternView.Cell> pattern) {
         if (pattern == null) {
             return null;
         }

         final int patternSize = pattern.size();
         byte[] res = new byte[patternSize];
         for (int i = 0; i < patternSize; i++) {
             LockPatternView.Cell cell = pattern.get(i);
             res[i] = (byte) (cell.getRow() * 3 + cell.getColumn());
         }
         try {
             MessageDigest md = MessageDigest.getInstance("SHA-1");
             byte[] hash = md.digest(res);
             return hash;
         } catch (NoSuchAlgorithmException nsa) {
             return res;
         }
     }

     private String getSalt() {
         long salt = getLong(LOCK_PASSWORD_SALT_KEY, 0);
         if (salt == 0) {
             try {
                 salt = SecureRandom.getInstance("SHA1PRNG").nextLong();
                 setLong(LOCK_PASSWORD_SALT_KEY, salt);
                 Log.v(TAG, "Initialized lock password salt");
             } catch (NoSuchAlgorithmException e) {
                 // Throw an exception rather than storing a password we'll never be able to recover
                 throw new IllegalStateException("Couldn't get SecureRandom number", e);
             }
         }
         return Long.toHexString(salt);
     }

     /*
      * Generate a hash for the given password. To avoid brute force attacks, we use a salted hash.
      * Not the most secure, but it is at least a second level of protection. First level is that
      * the file is in a location only readable by the system process.
      * @param password the gesture pattern.
      * @return the hash of the pattern in a byte array.
      */
      public byte[] passwordToHash(String password) {
         if (password == null) {
             return null;
         }
         String algo = null;
         byte[] hashed = null;
         try {
             byte[] saltedPassword = (password + getSalt()).getBytes();
             byte[] sha1 = MessageDigest.getInstance(algo = "SHA-1").digest(saltedPassword);
             byte[] md5 = MessageDigest.getInstance(algo = "MD5").digest(saltedPassword);
             hashed = (toHex(sha1) + toHex(md5)).getBytes();
         } catch (NoSuchAlgorithmException e) {
             Log.w(TAG, "Failed to encode string because of missing algorithm: " + algo);
         }
         return hashed;
     }

     private static String toHex(byte[] ary) {
         final String hex = "0123456789ABCDEF";
         String ret = "";
         for (int i = 0; i < ary.length; i++) {
             ret += hex.charAt((ary[i] >> 4) & 0xf);
             ret += hex.charAt(ary[i] & 0xf);
         }
         return ret;
     }

     /**
      * @return Whether the lock password is enabled.
      */
     public boolean isLockPasswordEnabled() {
         long mode = getLong(PASSWORD_TYPE_KEY, 0);
         return savedPasswordExists() && (mode == MODE_PASSWORD || mode == MODE_PIN);
     }

     /**
      * @return Whether the lock pattern is enabled.
      */
     public boolean isLockPatternEnabled() {
         return getBoolean(Settings.System.LOCK_PATTERN_ENABLED)
                 && getLong(PASSWORD_TYPE_KEY, MODE_PATTERN) == MODE_PATTERN;
     }

     /**
      * Set whether the lock pattern is enabled.
      */
     public void setLockPatternEnabled(boolean enabled) {
         setBoolean(Settings.System.LOCK_PATTERN_ENABLED, enabled);
     }

     /**
      * @return Whether the visible pattern is enabled.
      */
     public boolean isVisiblePatternEnabled() {
         return getBoolean(Settings.System.LOCK_PATTERN_VISIBLE);
     }

     /**
      * Set whether the visible pattern is enabled.
      */
     public void setVisiblePatternEnabled(boolean enabled) {
         setBoolean(Settings.System.LOCK_PATTERN_VISIBLE, enabled);
     }

     /**
      * @return Whether tactile feedback for the pattern is enabled.
      */
     public boolean isTactileFeedbackEnabled() {
         return getBoolean(Settings.System.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED);
     }

     /**
      * Set whether tactile feedback for the pattern is enabled.
      */
     public void setTactileFeedbackEnabled(boolean enabled) {
         setBoolean(Settings.System.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED, enabled);
     }

     /**
      * Set and store the lockout deadline, meaning the user can't attempt his/her unlock
      * pattern until the deadline has passed.
      * @return the chosen deadline.
      */
     public long setLockoutAttemptDeadline() {
         final long deadline = SystemClock.elapsedRealtime() + FAILED_ATTEMPT_TIMEOUT_MS;
         setLong(LOCKOUT_ATTEMPT_DEADLINE, deadline);
         return deadline;
     }

     /**
      * @return The elapsed time in millis in the future when the user is allowed to
      *   attempt to enter his/her lock pattern, or 0 if the user is welcome to
      *   enter a pattern.
      */
     public long getLockoutAttemptDeadline() {
         final long deadline = getLong(LOCKOUT_ATTEMPT_DEADLINE, 0L);
         final long now = SystemClock.elapsedRealtime();
         if (deadline < now || deadline > (now + FAILED_ATTEMPT_TIMEOUT_MS)) {
             return 0L;
         }
         return deadline;
     }

     /**
      * @return Whether the user is permanently locked out until they verify their
      *   credentials.  Occurs after {@link #FAILED_ATTEMPTS_BEFORE_RESET} failed
      *   attempts.
      */
     public boolean isPermanentlyLocked() {
         return getBoolean(LOCKOUT_PERMANENT_KEY);
     }

     /**
      * Set the state of whether the device is permanently locked, meaning the user
      * must authenticate via other means.
      *
      * @param locked Whether the user is permanently locked out until they verify their
      *   credentials.  Occurs after {@link #FAILED_ATTEMPTS_BEFORE_RESET} failed
      *   attempts.
      */
     public void setPermanentlyLocked(boolean locked) {
         setBoolean(LOCKOUT_PERMANENT_KEY, locked);
     }

     /**
      * @return A formatted string of the next alarm (for showing on the lock screen),
      *   or null if there is no next alarm.
      */
     public String getNextAlarm() {
         String nextAlarm = Settings.System.getString(mContentResolver,
                 Settings.System.NEXT_ALARM_FORMATTED);
         if (nextAlarm == null || TextUtils.isEmpty(nextAlarm)) {
             return null;
         }
         return nextAlarm;
     }

     private boolean getBoolean(String systemSettingKey) {
         // STOPSHIP: these need to be moved to secure settings!
         return 1 ==
                 android.provider.Settings.System.getInt(
                         mContentResolver,
                         systemSettingKey, 0);
     }

     private void setBoolean(String systemSettingKey, boolean enabled) {
         // STOPSHIP: these need to be moved to secure settings!
         android.provider.Settings.System.putInt(
                         mContentResolver,
                         systemSettingKey,
                         enabled ? 1 : 0);
     }

     private long getLong(String systemSettingKey, long def) {
         // STOPSHIP: these need to be moved to secure settings!
         return android.provider.Settings.System.getLong(mContentResolver, systemSettingKey, def);
     }

     private void setLong(String systemSettingKey, long value) {
         // STOPSHIP: these need to be moved to secure settings!
         android.provider.Settings.System.putLong(mContentResolver, systemSettingKey, value);
     }

     public boolean isSecure() {
         long mode = getPasswordMode();
         boolean secure = mode == MODE_PATTERN && isLockPatternEnabled() && savedPatternExists()
             || (mode == MODE_PIN || mode == MODE_PASSWORD) && savedPasswordExists();
         return secure;
     }
 }
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.internal.widget;

	import android.app.DevicePolicyManager;
	import android.content.ComponentName;
	import android.content.ContentResolver;
	import android.content.Context;
	import android.os.SystemClock;
	import android.provider.Settings;
	import android.security.MessageDigest;
	import android.text.TextUtils;
	import android.util.Log;

	import com.google.android.collect.Lists;

	import java.io.FileNotFoundException;
	import java.io.IOException;
	import java.io.RandomAccessFile;
	import java.security.NoSuchAlgorithmException;
	import java.security.SecureRandom;
	import java.util.Arrays;
	import java.util.List;

	/**
	* Utilities for the lock patten and its settings.
	*/
	public class LockPatternUtils {

	private static final String TAG = "LockPatternUtils";

	private static final String LOCK_PATTERN_FILE = "/system/gesture.key";
	private static final String LOCK_PASSWORD_FILE = "/system/password.key";

	/**
	* The maximum number of incorrect attempts before the user is prevented
	* from trying again for {@link #FAILED_ATTEMPT_TIMEOUT_MS}.
	*/
	public static final int FAILED_ATTEMPTS_BEFORE_TIMEOUT = 5;

	/**
	* The number of incorrect attempts before which we fall back on an alternative
	* method of verifying the user, and resetting their lock pattern.
	*/
	public static final int FAILED_ATTEMPTS_BEFORE_RESET = 20;

	/**
	* How long the user is prevented from trying again after entering the
	* wrong pattern too many times.
	*/
	public static final long FAILED_ATTEMPT_TIMEOUT_MS = 30000L;

	/**
	* The interval of the countdown for showing progress of the lockout.
	*/
	public static final long FAILED_ATTEMPT_COUNTDOWN_INTERVAL_MS = 1000L;

	/**
	* The minimum number of dots in a valid pattern.
	*/
	public static final int MIN_LOCK_PATTERN_SIZE = 4;

	/**
	* Type of password being stored.
	* pattern = pattern screen
	* pin = digit-only password
	* password = alphanumeric password
	*/
	public static final int MODE_PATTERN = DevicePolicyManager.PASSWORD_MODE_SOMETHING;
	public static final int MODE_PIN = DevicePolicyManager.PASSWORD_MODE_NUMERIC;
	public static final int MODE_PASSWORD = DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC;

	/**
	* The minimum number of dots the user must include in a wrong pattern
	* attempt for it to be counted against the counts that affect
	* {@link #FAILED_ATTEMPTS_BEFORE_TIMEOUT} and {@link #FAILED_ATTEMPTS_BEFORE_RESET}
	*/
	public static final int MIN_PATTERN_REGISTER_FAIL = 3;

	private final static String LOCKOUT_PERMANENT_KEY = "lockscreen.lockedoutpermanently";
	private final static String LOCKOUT_ATTEMPT_DEADLINE = "lockscreen.lockoutattemptdeadline";
	private final static String PATTERN_EVER_CHOSEN_KEY = "lockscreen.patterneverchosen";
	public final static String PASSWORD_TYPE_KEY = "lockscreen.password_type";
	private final static String LOCK_PASSWORD_SALT_KEY = "lockscreen.password_salt";

	private final Context mContext;
	private final ContentResolver mContentResolver;
	private DevicePolicyManager mDevicePolicyManager;
	private static String sLockPatternFilename;
	private static String sLockPasswordFilename;

	/**
	* @param contentResolver Used to look up and save settings.
	*/
	public LockPatternUtils(Context context) {
	mContext = context;
	mContentResolver = context.getContentResolver();
	mDevicePolicyManager =
	(DevicePolicyManager)context.getSystemService(Context.DEVICE_POLICY_SERVICE);
	// Initialize the location of gesture lock file
	if (sLockPatternFilename == null) {
	sLockPatternFilename = android.os.Environment.getDataDirectory()
	.getAbsolutePath() + LOCK_PATTERN_FILE;
	sLockPasswordFilename = android.os.Environment.getDataDirectory()
	.getAbsolutePath() + LOCK_PASSWORD_FILE;
	}

	}

	public int getRequestedMinimumPasswordLength() {
	return mDevicePolicyManager.getMinimumPasswordLength();
	}

	/**
	* Gets the device policy password mode. If the mode is non-specific, returns
	* MODE_PATTERN which allows the user to choose anything.
	*
	* @return
	*/
	public int getRequestedPasswordMode() {
	int policyMode = mDevicePolicyManager.getPasswordMode();
	switch (policyMode) {
	case DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC:
	return MODE_PASSWORD;
	case DevicePolicyManager.PASSWORD_MODE_NUMERIC:
	return MODE_PIN;
	case DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED:
	return MODE_PATTERN;
	}
	return MODE_PATTERN;
	}

	/**
	* Returns the actual password mode, as set by keyguard after updating the password.
	*
	* @return
	*/
	public void reportFailedPasswordAttempt() {
	mDevicePolicyManager.reportFailedPasswordAttempt();
	}

	public void reportSuccessfulPasswordAttempt() {
	mDevicePolicyManager.reportSuccessfulPasswordAttempt();
	}

	public void setActivePasswordState(int mode, int length) {
	int policyMode = DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED;
	switch (mode) {
	case MODE_PATTERN:
	policyMode = DevicePolicyManager.PASSWORD_MODE_UNSPECIFIED;
	break;
	case MODE_PIN:
	policyMode = DevicePolicyManager.PASSWORD_MODE_NUMERIC;
	break;
	case MODE_PASSWORD:
	policyMode = DevicePolicyManager.PASSWORD_MODE_ALPHANUMERIC;
	break;
	}
	mDevicePolicyManager.setActivePasswordState(policyMode, length);
	}

	/**
	* Check to see if a pattern matches the saved pattern. If no pattern exists,
	* always returns true.
	* @param pattern The pattern to check.
	* @return Whether the pattern matches the stored one.
	*/
	public boolean checkPattern(List<LockPatternView.Cell> pattern) {
	try {
	// Read all the bytes from the file
	RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "r");
	final byte[] stored = new byte[(int) raf.length()];
	int got = raf.read(stored, 0, stored.length);
	raf.close();
	if (got <= 0) {
	return true;
	}
	// Compare the hash from the file with the entered pattern's hash
	return Arrays.equals(stored, LockPatternUtils.patternToHash(pattern));
	} catch (FileNotFoundException fnfe) {
	return true;
	} catch (IOException ioe) {
	return true;
	}
	}

	/**
	* Check to see if a password matches the saved password. If no password exists,
	* always returns true.
	* @param password The password to check.
	* @return Whether the password matches the stored one.
	*/
	public boolean checkPassword(String password) {
	try {
	// Read all the bytes from the file
	RandomAccessFile raf = new RandomAccessFile(sLockPasswordFilename, "r");
	final byte[] stored = new byte[(int) raf.length()];
	int got = raf.read(stored, 0, stored.length);
	raf.close();
	if (got <= 0) {
	return true;
	}
	// Compare the hash from the file with the entered password's hash
	return Arrays.equals(stored, passwordToHash(password));
	} catch (FileNotFoundException fnfe) {
	return true;
	} catch (IOException ioe) {
	return true;
	}
	}

	/**
	* Checks to see if the given file exists and contains any data. Returns true if it does,
	* false otherwise.
	* @param filename
	* @return true if file exists and is non-empty.
	*/
	private boolean nonEmptyFileExists(String filename) {
	try {
	// Check if we can read a byte from the file
	RandomAccessFile raf = new RandomAccessFile(filename, "r");
	byte first = raf.readByte();
	raf.close();
	return true;
	} catch (FileNotFoundException fnfe) {
	return false;
	} catch (IOException ioe) {
	return false;
	}
	}

	/**
	* Check to see if the user has stored a lock pattern.
	* @return Whether a saved pattern exists.
	*/
	public boolean savedPatternExists() {
	return nonEmptyFileExists(sLockPatternFilename);
	}

	/**
	* Check to see if the user has stored a lock pattern.
	* @return Whether a saved pattern exists.
	*/
	public boolean savedPasswordExists() {
	return nonEmptyFileExists(sLockPasswordFilename);
	}

	/**
	* Return true if the user has ever chosen a pattern. This is true even if the pattern is
	* currently cleared.
	*
	* @return True if the user has ever chosen a pattern.
	*/
	public boolean isPatternEverChosen() {
	return getBoolean(PATTERN_EVER_CHOSEN_KEY);
	}

	/**
	* Clear any lock pattern or password.
	*/
	public void clearLock() {
	saveLockPassword(null, LockPatternUtils.MODE_PATTERN);
	setLockPatternEnabled(false);
	saveLockPattern(null);
	setLong(PASSWORD_TYPE_KEY, MODE_PATTERN);
	}

	/**
	* Save a lock pattern.
	* @param pattern The new pattern to save.
	*/
	public void saveLockPattern(List<LockPatternView.Cell> pattern) {
	// Compute the hash
	final byte[] hash = LockPatternUtils.patternToHash(pattern);
	try {
	// Write the hash to file
	RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "rw");
	// Truncate the file if pattern is null, to clear the lock
	if (pattern == null) {
	raf.setLength(0);
	} else {
	raf.write(hash, 0, hash.length);
	}
	raf.close();
	if (pattern != null) {
	setBoolean(PATTERN_EVER_CHOSEN_KEY, true);
	setLong(PASSWORD_TYPE_KEY, MODE_PATTERN);
	DevicePolicyManager dpm = (DevicePolicyManager)mContext.getSystemService(
	Context.DEVICE_POLICY_SERVICE);
	dpm.setActivePasswordState(
	DevicePolicyManager.PASSWORD_MODE_SOMETHING, pattern.size());
	}
	} catch (FileNotFoundException fnfe) {
	// Cant do much, unless we want to fail over to using the settings provider
	Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename);
	} catch (IOException ioe) {
	// Cant do much
	Log.e(TAG, "Unable to save lock pattern to " + sLockPatternFilename);
	}
	}

	/**
	* Save a lock password.
	* @param password The password to save
	*/
	public void saveLockPassword(String password, int mode) {
	// Compute the hash
	final byte[] hash = passwordToHash(password);
	try {
	// Write the hash to file
	RandomAccessFile raf = new RandomAccessFile(sLockPasswordFilename, "rw");
	// Truncate the file if pattern is null, to clear the lock
	if (password == null) {
	raf.setLength(0);
	} else {
	raf.write(hash, 0, hash.length);
	}
	raf.close();
	if (password != null) {
	int textMode = TextUtils.isDigitsOnly(password) ? MODE_PIN : MODE_PASSWORD;
	if (textMode > mode) {
	mode = textMode;
	}
	setLong(PASSWORD_TYPE_KEY, mode);
	DevicePolicyManager dpm = (DevicePolicyManager)mContext.getSystemService(
	Context.DEVICE_POLICY_SERVICE);
	dpm.setActivePasswordState(mode, password.length());
	}
	} catch (FileNotFoundException fnfe) {
	// Cant do much, unless we want to fail over to using the settings provider
	Log.e(TAG, "Unable to save lock pattern to " + sLockPasswordFilename);
	} catch (IOException ioe) {
	// Cant do much
	Log.e(TAG, "Unable to save lock pattern to " + sLockPasswordFilename);
	}
	}

	public int getPasswordMode() {
	return (int) getLong(PASSWORD_TYPE_KEY, MODE_PATTERN);
	}

	/**
	* Deserialize a pattern.
	* @param string The pattern serialized with {@link #patternToString}
	* @return The pattern.
	*/
	public static List<LockPatternView.Cell> stringToPattern(String string) {
	List<LockPatternView.Cell> result = Lists.newArrayList();

	final byte[] bytes = string.getBytes();
	for (int i = 0; i < bytes.length; i++) {
	byte b = bytes[i];
	result.add(LockPatternView.Cell.of(b / 3, b % 3));
	}
	return result;
	}

	/**
	* Serialize a pattern.
	* @param pattern The pattern.
	* @return The pattern in string form.
	*/
	public static String patternToString(List<LockPatternView.Cell> pattern) {
	if (pattern == null) {
	return "";
	}
	final int patternSize = pattern.size();

	byte[] res = new byte[patternSize];
	for (int i = 0; i < patternSize; i++) {
	LockPatternView.Cell cell = pattern.get(i);
	res[i] = (byte) (cell.getRow() * 3 + cell.getColumn());
	}
	return new String(res);
	}

	/*
	* Generate an SHA-1 hash for the pattern. Not the most secure, but it is
	* at least a second level of protection. First level is that the file
	* is in a location only readable by the system process.
	* @param pattern the gesture pattern.
	* @return the hash of the pattern in a byte array.
	*/
	private static byte[] patternToHash(List<LockPatternView.Cell> pattern) {
	if (pattern == null) {
	return null;
	}

	final int patternSize = pattern.size();
	byte[] res = new byte[patternSize];
	for (int i = 0; i < patternSize; i++) {
	LockPatternView.Cell cell = pattern.get(i);
	res[i] = (byte) (cell.getRow() * 3 + cell.getColumn());
	}
	try {
	MessageDigest md = MessageDigest.getInstance("SHA-1");
	byte[] hash = md.digest(res);
	return hash;
	} catch (NoSuchAlgorithmException nsa) {
	return res;
	}
	}

	private String getSalt() {
	long salt = getLong(LOCK_PASSWORD_SALT_KEY, 0);
	if (salt == 0) {
	try {
	salt = SecureRandom.getInstance("SHA1PRNG").nextLong();
	setLong(LOCK_PASSWORD_SALT_KEY, salt);
	Log.v(TAG, "Initialized lock password salt");
	} catch (NoSuchAlgorithmException e) {
	// Throw an exception rather than storing a password we'll never be able to recover
	throw new IllegalStateException("Couldn't get SecureRandom number", e);
	}
	}
	return Long.toHexString(salt);
	}

	/*
	* Generate a hash for the given password. To avoid brute force attacks, we use a salted hash.
	* Not the most secure, but it is at least a second level of protection. First level is that
	* the file is in a location only readable by the system process.
	* @param password the gesture pattern.
	* @return the hash of the pattern in a byte array.
	*/
	public byte[] passwordToHash(String password) {
	if (password == null) {
	return null;
	}
	String algo = null;
	byte[] hashed = null;
	try {
	byte[] saltedPassword = (password + getSalt()).getBytes();
	byte[] sha1 = MessageDigest.getInstance(algo = "SHA-1").digest(saltedPassword);
	byte[] md5 = MessageDigest.getInstance(algo = "MD5").digest(saltedPassword);
	hashed = (toHex(sha1) + toHex(md5)).getBytes();
	} catch (NoSuchAlgorithmException e) {
	Log.w(TAG, "Failed to encode string because of missing algorithm: " + algo);
	}
	return hashed;
	}

	private static String toHex(byte[] ary) {
	final String hex = "0123456789ABCDEF";
	String ret = "";
	for (int i = 0; i < ary.length; i++) {
	ret += hex.charAt((ary[i] >> 4) & 0xf);
	ret += hex.charAt(ary[i] & 0xf);
	}
	return ret;
	}

	/**
	* @return Whether the lock password is enabled.
	*/
	public boolean isLockPasswordEnabled() {
	long mode = getLong(PASSWORD_TYPE_KEY, 0);
	return savedPasswordExists() && (mode == MODE_PASSWORD \|\| mode == MODE_PIN);
	}

	/**
	* @return Whether the lock pattern is enabled.
	*/
	public boolean isLockPatternEnabled() {
	return getBoolean(Settings.System.LOCK_PATTERN_ENABLED)
	&& getLong(PASSWORD_TYPE_KEY, MODE_PATTERN) == MODE_PATTERN;
	}

	/**
	* Set whether the lock pattern is enabled.
	*/
	public void setLockPatternEnabled(boolean enabled) {
	setBoolean(Settings.System.LOCK_PATTERN_ENABLED, enabled);
	}

	/**
	* @return Whether the visible pattern is enabled.
	*/
	public boolean isVisiblePatternEnabled() {
	return getBoolean(Settings.System.LOCK_PATTERN_VISIBLE);
	}

	/**
	* Set whether the visible pattern is enabled.
	*/
	public void setVisiblePatternEnabled(boolean enabled) {
	setBoolean(Settings.System.LOCK_PATTERN_VISIBLE, enabled);
	}

	/**
	* @return Whether tactile feedback for the pattern is enabled.
	*/
	public boolean isTactileFeedbackEnabled() {
	return getBoolean(Settings.System.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED);
	}

	/**
	* Set whether tactile feedback for the pattern is enabled.
	*/
	public void setTactileFeedbackEnabled(boolean enabled) {
	setBoolean(Settings.System.LOCK_PATTERN_TACTILE_FEEDBACK_ENABLED, enabled);
	}

	/**
	* Set and store the lockout deadline, meaning the user can't attempt his/her unlock
	* pattern until the deadline has passed.
	* @return the chosen deadline.
	*/
	public long setLockoutAttemptDeadline() {
	final long deadline = SystemClock.elapsedRealtime() + FAILED_ATTEMPT_TIMEOUT_MS;
	setLong(LOCKOUT_ATTEMPT_DEADLINE, deadline);
	return deadline;
	}

	/**
	* @return The elapsed time in millis in the future when the user is allowed to
	* attempt to enter his/her lock pattern, or 0 if the user is welcome to
	* enter a pattern.
	*/
	public long getLockoutAttemptDeadline() {
	final long deadline = getLong(LOCKOUT_ATTEMPT_DEADLINE, 0L);
	final long now = SystemClock.elapsedRealtime();
	if (deadline < now \|\| deadline > (now + FAILED_ATTEMPT_TIMEOUT_MS)) {
	return 0L;
	}
	return deadline;
	}

	/**
	* @return Whether the user is permanently locked out until they verify their
	* credentials. Occurs after {@link #FAILED_ATTEMPTS_BEFORE_RESET} failed
	* attempts.
	*/
	public boolean isPermanentlyLocked() {
	return getBoolean(LOCKOUT_PERMANENT_KEY);
	}

	/**
	* Set the state of whether the device is permanently locked, meaning the user
	* must authenticate via other means.
	*
	* @param locked Whether the user is permanently locked out until they verify their
	* credentials. Occurs after {@link #FAILED_ATTEMPTS_BEFORE_RESET} failed
	* attempts.
	*/
	public void setPermanentlyLocked(boolean locked) {
	setBoolean(LOCKOUT_PERMANENT_KEY, locked);
	}

	/**
	* @return A formatted string of the next alarm (for showing on the lock screen),
	* or null if there is no next alarm.
	*/
	public String getNextAlarm() {
	String nextAlarm = Settings.System.getString(mContentResolver,
	Settings.System.NEXT_ALARM_FORMATTED);
	if (nextAlarm == null \|\| TextUtils.isEmpty(nextAlarm)) {
	return null;
	}
	return nextAlarm;
	}

	private boolean getBoolean(String systemSettingKey) {
	// STOPSHIP: these need to be moved to secure settings!
	return 1 ==
	android.provider.Settings.System.getInt(
	mContentResolver,
	systemSettingKey, 0);
	}

	private void setBoolean(String systemSettingKey, boolean enabled) {
	// STOPSHIP: these need to be moved to secure settings!
	android.provider.Settings.System.putInt(
	mContentResolver,
	systemSettingKey,
	enabled ? 1 : 0);
	}

	private long getLong(String systemSettingKey, long def) {
	// STOPSHIP: these need to be moved to secure settings!
	return android.provider.Settings.System.getLong(mContentResolver, systemSettingKey, def);
	}

	private void setLong(String systemSettingKey, long value) {
	// STOPSHIP: these need to be moved to secure settings!
	android.provider.Settings.System.putLong(mContentResolver, systemSettingKey, value);
	}

	public boolean isSecure() {
	long mode = getPasswordMode();
	boolean secure = mode == MODE_PATTERN && isLockPatternEnabled() && savedPatternExists()
	\|\| (mode == MODE_PIN \|\| mode == MODE_PASSWORD) && savedPasswordExists();
	return secure;
	}
	}