Merge "Make password history hashing more secure" into pi-dev (66b6d1c3) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/widget/ILockSettings.aidl

+1 −0

Original line number	Diff line number	Diff line
		@@ -45,6 +45,7 @@ interface ILockSettings {
		boolean checkVoldPassword(int userId);
		boolean havePattern(int userId);
		boolean havePassword(int userId);
		byte[] getHashFactor(String currentCredential, int userId);
		void setSeparateProfileChallengeEnabled(int userId, boolean enabled, String managedUserPassword);
		boolean getSeparateProfileChallengeEnabled(int userId);
		void registerStrongAuthTracker(in IStrongAuthTracker tracker);

core/java/com/android/internal/widget/LockPatternUtils.java

+81 −24

Original line number	Diff line number	Diff line
		@@ -66,8 +66,10 @@ import java.security.MessageDigest;
		import java.security.NoSuchAlgorithmException;
		import java.security.SecureRandom;
		import java.util.ArrayList;
		import java.util.Arrays;
		import java.util.Collection;
		import java.util.List;
		import java.util.StringJoiner;
		/**
		* Utilities for the lock pattern and its settings.
		*/
		@@ -165,6 +167,7 @@ public class LockPatternUtils {

		public static final String SYNTHETIC_PASSWORD_HANDLE_KEY = "sp-handle";
		public static final String SYNTHETIC_PASSWORD_ENABLED_KEY = "enable-sp";
		private static final String HISTORY_DELIMITER = ",";

		private final Context mContext;
		private final ContentResolver mContentResolver;
		@@ -506,32 +509,51 @@ public class LockPatternUtils {
		}
		}

		/**
		* Returns the password history hash factor, needed to check new password against password
		* history with {@link #checkPasswordHistory(String, byte[], int)}
		*/
		public byte[] getPasswordHistoryHashFactor(String currentPassword, int userId) {
		try {
		return getLockSettings().getHashFactor(currentPassword, userId);
		} catch (RemoteException e) {
		Log.e(TAG, "failed to get hash factor", e);
		return null;
		}
		}

		/**
		* Check to see if a password matches any of the passwords stored in the
		* password history.
		*
		* @param password The password to check.
		* @param passwordToCheck The password to check.
		* @param hashFactor Hash factor of the current user returned from
		* {@link ILockSettings#getHashFactor}
		* @return Whether the password matches any in the history.
		*/
		public boolean checkPasswordHistory(String password, int userId) {
		String passwordHashString = new String(
		passwordToHash(password, userId), StandardCharsets.UTF_8);
		public boolean checkPasswordHistory(String passwordToCheck, byte[] hashFactor, int userId) {
		if (TextUtils.isEmpty(passwordToCheck)) {
		Log.e(TAG, "checkPasswordHistory: empty password");
		return false;
		}
		String passwordHistory = getString(PASSWORD_HISTORY_KEY, userId);
		if (passwordHistory == null) {
		if (TextUtils.isEmpty(passwordHistory)) {
		return false;
		}
		// Password History may be too long...
		int passwordHashLength = passwordHashString.length();
		int passwordHistoryLength = getRequestedPasswordHistoryLength(userId);
		if(passwordHistoryLength == 0) {
		return false;
		}
		int neededPasswordHistoryLength = passwordHashLength * passwordHistoryLength
		+ passwordHistoryLength - 1;
		if (passwordHistory.length() > neededPasswordHistoryLength) {
		passwordHistory = passwordHistory.substring(0, neededPasswordHistoryLength);
		String legacyHash = legacyPasswordToHash(passwordToCheck, userId);
		String passwordHash = passwordToHistoryHash(passwordToCheck, hashFactor, userId);
		String[] history = passwordHistory.split(HISTORY_DELIMITER);
		// Password History may be too long...
		for (int i = 0; i < Math.min(passwordHistoryLength, history.length); i++) {
		if (history[i].equals(legacyHash) \|\| history[i].equals(passwordHash)) {
		return true;
		}
		}
		return passwordHistory.contains(passwordHashString);
		return false;
		}

		/**
		@@ -830,6 +852,7 @@ public class LockPatternUtils {
		updateEncryptionPasswordIfNeeded(password,
		PasswordMetrics.computeForPassword(password).quality, userHandle);
		updatePasswordHistory(password, userHandle);
		onAfterChangingPassword(userHandle);
		}

		/**
		@@ -852,8 +875,15 @@ public class LockPatternUtils {
		}
		}

		/**
		* Store the hash of the current password in the password history list, if device policy
		* enforces password history requirement.
		*/
		private void updatePasswordHistory(String password, int userHandle) {

		if (TextUtils.isEmpty(password)) {
		Log.e(TAG, "checkPasswordHistory: empty password");
		return;
		}
		// Add the password to the password history. We assume all
		// password hashes have the same length for simplicity of implementation.
		String passwordHistory = getString(PASSWORD_HISTORY_KEY, userHandle);
		@@ -864,16 +894,25 @@ public class LockPatternUtils {
		if (passwordHistoryLength == 0) {
		passwordHistory = "";
		} else {
		byte[] hash = passwordToHash(password, userHandle);
		passwordHistory = new String(hash, StandardCharsets.UTF_8) + "," + passwordHistory;
		// Cut it to contain passwordHistoryLength hashes
		// and passwordHistoryLength -1 commas.
		passwordHistory = passwordHistory.substring(0, Math.min(hash.length
		* passwordHistoryLength + passwordHistoryLength - 1, passwordHistory
		.length()));
		final byte[] hashFactor = getPasswordHistoryHashFactor(password, userHandle);
		String hash = passwordToHistoryHash(password, hashFactor, userHandle);
		if (hash == null) {
		Log.e(TAG, "Compute new style password hash failed, fallback to legacy style");
		hash = legacyPasswordToHash(password, userHandle);
		}
		if (TextUtils.isEmpty(passwordHistory)) {
		passwordHistory = hash;
		} else {
		String[] history = passwordHistory.split(HISTORY_DELIMITER);
		StringJoiner joiner = new StringJoiner(HISTORY_DELIMITER);
		joiner.add(hash);
		for (int i = 0; i < passwordHistoryLength - 1 && i < history.length; i++) {
		joiner.add(history[i]);
		}
		passwordHistory = joiner.toString();
		}
		}
		setString(PASSWORD_HISTORY_KEY, passwordHistory, userHandle);
		onAfterChangingPassword(userHandle);
		}

		/**
		@@ -1098,7 +1137,7 @@ public class LockPatternUtils {
		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.
		@@ -1107,7 +1146,7 @@ public class LockPatternUtils {
		*
		* @return the hash of the pattern in a byte array.
		*/
		public byte[] passwordToHash(String password, int userId) {
		public String legacyPasswordToHash(String password, int userId) {
		if (password == null) {
		return null;
		}
		@@ -1122,7 +1161,24 @@ public class LockPatternUtils {
		System.arraycopy(md5, 0, combined, sha1.length, md5.length);

		final char[] hexEncoded = HexEncoding.encode(combined);
		return new String(hexEncoded).getBytes(StandardCharsets.UTF_8);
		return new String(hexEncoded);
		} catch (NoSuchAlgorithmException e) {
		throw new AssertionError("Missing digest algorithm: ", e);
		}
		}

		/**
		* Hash the password for password history check purpose.
		*/
		private String passwordToHistoryHash(String passwordToHash, byte[] hashFactor, int userId) {
		if (TextUtils.isEmpty(passwordToHash) \|\| hashFactor == null) {
		return null;
		}
		try {
		MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
		sha256.update(hashFactor);
		sha256.update((passwordToHash + getSalt(userId)).getBytes());
		return new String(HexEncoding.encode(sha256.digest()));
		} catch (NoSuchAlgorithmException e) {
		throw new AssertionError("Missing digest algorithm: ", e);
		}
		@@ -1571,6 +1627,7 @@ public class LockPatternUtils {

		updateEncryptionPasswordIfNeeded(credential, quality, userId);
		updatePasswordHistory(credential, userId);
		onAfterChangingPassword(userId);
		} else {
		if (!TextUtils.isEmpty(credential)) {
		throw new IllegalArgumentException("password must be emtpy for NONE type");

services/core/java/com/android/server/locksettings/LockSettingsService.java

+29 −1

Original line number	Diff line number	Diff line
		@@ -1742,7 +1742,8 @@ public class LockSettingsService extends ILockSettings.Stub {
		if (storedHash.type == LockPatternUtils.CREDENTIAL_TYPE_PATTERN) {
		hash = LockPatternUtils.patternToHash(LockPatternUtils.stringToPattern(credential));
		} else {
		hash = mLockPatternUtils.passwordToHash(credential, userId);
		hash = mLockPatternUtils.legacyPasswordToHash(credential, userId)
		.getBytes(StandardCharsets.UTF_8);
		}
		if (Arrays.equals(hash, storedHash.hash)) {
		if (storedHash.type == LockPatternUtils.CREDENTIAL_TYPE_PATTERN) {
		@@ -2532,6 +2533,33 @@ public class LockSettingsService extends ILockSettings.Stub {
		mRecoverableKeyStoreManager.lockScreenSecretChanged(credentialType, credential, userId);
		}

		/**
		* Returns a fixed pseudorandom byte string derived from the user's synthetic password.
		* This is used to salt the password history hash to protect the hash against offline
		* bruteforcing, since rederiving this value requires a successful authentication.
		*/
		@Override
		public byte[] getHashFactor(String currentCredential, int userId) throws RemoteException {
		checkPasswordReadPermission(userId);
		if (TextUtils.isEmpty(currentCredential)) {
		currentCredential = null;
		}
		synchronized (mSpManager) {
		if (!isSyntheticPasswordBasedCredentialLocked(userId)) {
		Slog.w(TAG, "Synthetic password not enabled");
		return null;
		}
		long handle = getSyntheticPasswordHandleLocked(userId);
		AuthenticationResult auth = mSpManager.unwrapPasswordBasedSyntheticPassword(
		getGateKeeperService(), handle, currentCredential, userId, null);
		if (auth.authToken == null) {
		Slog.w(TAG, "Current credential is incorrect");
		return null;
		}
		return auth.authToken.derivePasswordHashFactor();
		}
		}

		private long addEscrowToken(byte[] token, int userId) throws RemoteException {
		if (DEBUG) Slog.d(TAG, "addEscrowToken: user=" + userId);
		synchronized (mSpManager) {

services/core/java/com/android/server/locksettings/SyntheticPasswordManager.java

+6 −0

Original line number	Diff line number	Diff line
		@@ -123,6 +123,7 @@ public class SyntheticPasswordManager {
		private static final byte[] PERSONALIZATION_FBE_KEY = "fbe-key".getBytes();
		private static final byte[] PERSONALIZATION_AUTHSECRET_KEY = "authsecret-hal".getBytes();
		private static final byte[] PERSONALIZATION_SP_SPLIT = "sp-split".getBytes();
		private static final byte[] PERSONALIZATION_PASSWORD_HASH = "pw-hash".getBytes();
		private static final byte[] PERSONALIZATION_E0 = "e0-encryption".getBytes();
		private static final byte[] PERSONALISATION_WEAVER_PASSWORD = "weaver-pwd".getBytes();
		private static final byte[] PERSONALISATION_WEAVER_KEY = "weaver-key".getBytes();
		@@ -165,6 +166,11 @@ public class SyntheticPasswordManager {
		syntheticPassword.getBytes());
		}

		public byte[] derivePasswordHashFactor() {
		return SyntheticPasswordCrypto.personalisedHash(PERSONALIZATION_PASSWORD_HASH,
		syntheticPassword.getBytes());
		}

		private void initialize(byte[] P0, byte[] P1) {
		this.P1 = P1;
		this.syntheticPassword = String.valueOf(HexEncoding.encode(