/*
* 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.content.ContentResolver;
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.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";
/**
* 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;
/**
* 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 = "lockscreen.patterneverchosen";
private final ContentResolver mContentResolver;
private static String sLockPatternFilename;
/**
* @param contentResolver Used to look up and save settings.
*/
public LockPatternUtils(ContentResolver contentResolver) {
mContentResolver = contentResolver;
// Initialize the location of gesture lock file
if (sLockPatternFilename == null) {
sLockPatternFilename = android.os.Environment.getDataDirectory()
.getAbsolutePath() + LOCK_PATTERN_FILE;
}
}
/**
* 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 matchees 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 the user has stored a lock pattern.
* @return Whether a saved pattern exists.
*/
public boolean savedPatternExists() {
try {
// Check if we can read a byte from the file
RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename, "r");
byte first = raf.readByte();
raf.close();
return true;
} catch (FileNotFoundException fnfe) {
return false;
} catch (IOException ioe) {
return false;
}
}
/**
* 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);
}
/**
* 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();
setBoolean(PATTERN_EVER_CHOSEN, true);
} 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);
}
}
/**
* 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.
*/
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;
}
}
/**
* @return Whether the lock pattern is enabled.
*/
public boolean isLockPatternEnabled() {
return getBoolean(Settings.System.LOCK_PATTERN_ENABLED);
}
/**
* 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. If false, that means the user has gone
* out of permanent lock, so the existing (forgotten) lock pattern needs to
* be cleared.
* @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);
if (!locked) {
setLockPatternEnabled(false);
saveLockPattern(null);
}
}
/**
* @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) {
return 1 ==
android.provider.Settings.System.getInt(
mContentResolver,
systemSettingKey, 0);
}
private void setBoolean(String systemSettingKey, boolean enabled) {
android.provider.Settings.System.putInt(
mContentResolver,
systemSettingKey,
enabled ? 1 : 0);
}
private long getLong(String systemSettingKey, long def) {
return android.provider.Settings.System.getLong(mContentResolver, systemSettingKey, def);
}
private void setLong(String systemSettingKey, long value) {
android.provider.Settings.System.putLong(mContentResolver, systemSettingKey, value);
}
}
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