Import TertiaryKeyManager

/*

 * Copyright (C) 2019 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.server.backup.encryption.keys;

import android.annotation.Nullable;

import android.content.Context;

import android.util.Slog;

import com.android.server.backup.encryption.protos.nano.WrappedKeyProto;

import java.io.IOException;

import java.security.InvalidAlgorithmParameterException;

import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

import java.util.Optional;

import javax.crypto.IllegalBlockSizeException;

import javax.crypto.NoSuchPaddingException;

import javax.crypto.SecretKey;

/**

 * Gets the correct tertiary key to use during a backup, rotating it if required.

 *

 * <p>Calling any method on this class will count a incremental backup against the app, and the key

 * will be rotated if required.

 */

public class TertiaryKeyManager {

    private static final String TAG = "TertiaryKeyMgr";

    private final TertiaryKeyStore mKeyStore;

    private final TertiaryKeyGenerator mKeyGenerator;

    private final TertiaryKeyRotationScheduler mTertiaryKeyRotationScheduler;

    private final RecoverableKeyStoreSecondaryKey mSecondaryKey;

    private final String mPackageName;

    private boolean mKeyRotated;

    @Nullable private SecretKey mTertiaryKey;

    public TertiaryKeyManager(

            Context context,

            SecureRandom secureRandom,

            TertiaryKeyRotationScheduler tertiaryKeyRotationScheduler,

            RecoverableKeyStoreSecondaryKey secondaryKey,

            String packageName) {

        mSecondaryKey = secondaryKey;

        mPackageName = packageName;

        mKeyGenerator = new TertiaryKeyGenerator(secureRandom);

        mKeyStore = TertiaryKeyStore.newInstance(context, secondaryKey);

        mTertiaryKeyRotationScheduler = tertiaryKeyRotationScheduler;

    }

    /**

     * Returns either the previously used tertiary key, or a new tertiary key if there was no

     * previous key or it needed to be rotated.

     */

    public SecretKey getKey()

            throws InvalidKeyException, IOException, IllegalBlockSizeException,

                    NoSuchPaddingException, NoSuchAlgorithmException,

                    InvalidAlgorithmParameterException {

        init();

        return mTertiaryKey;

    }

    /** Returns the key given by {@link #getKey()} wrapped by the secondary key. */

    public WrappedKeyProto.WrappedKey getWrappedKey()

            throws InvalidKeyException, IOException, IllegalBlockSizeException,

                    NoSuchPaddingException, NoSuchAlgorithmException,

                    InvalidAlgorithmParameterException {

        init();

        return KeyWrapUtils.wrap(mSecondaryKey.getSecretKey(), mTertiaryKey);

    }

    /**

     * Returns {@code true} if a new tertiary key was generated at the start of this session,

     * otherwise {@code false}.

     */

    public boolean wasKeyRotated()

            throws InvalidKeyException, IllegalBlockSizeException, IOException,

                    NoSuchPaddingException, NoSuchAlgorithmException,

                    InvalidAlgorithmParameterException {

        init();

        return mKeyRotated;

    }

    private void init()

            throws IllegalBlockSizeException, InvalidKeyException, IOException,

                    NoSuchAlgorithmException, NoSuchPaddingException,

                    InvalidAlgorithmParameterException {

        if (mTertiaryKey != null) {

            return;

        }

        Optional<SecretKey> key = getExistingKeyIfNotRotated();

        if (!key.isPresent()) {

            Slog.d(TAG, "Generating new tertiary key for " + mPackageName);

            key = Optional.of(mKeyGenerator.generate());

            mKeyRotated = true;

            mTertiaryKeyRotationScheduler.recordKeyRotation(mPackageName);

            mKeyStore.save(mPackageName, key.get());

        }

        mTertiaryKey = key.get();

        mTertiaryKeyRotationScheduler.recordBackup(mPackageName);

    }

    private Optional<SecretKey> getExistingKeyIfNotRotated()

            throws InvalidKeyException, IOException, InvalidAlgorithmParameterException,

                    NoSuchAlgorithmException, NoSuchPaddingException {

        if (mTertiaryKeyRotationScheduler.isKeyRotationDue(mPackageName)) {

            Slog.i(TAG, "Tertiary key rotation was required for " + mPackageName);

            return Optional.empty();

        } else {

            Slog.i(TAG, "Tertiary key rotation was not required");

            return mKeyStore.load(mPackageName);

        }

    }

}

/*

 * Copyright (C) 2019 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.server.backup.encryption.keys;

import static com.google.common.truth.Truth.assertThat;

import static org.mockito.ArgumentMatchers.any;

import static org.mockito.Mockito.inOrder;

import static org.mockito.Mockito.never;

import static org.mockito.Mockito.reset;

import static org.mockito.Mockito.verify;

import static org.mockito.Mockito.when;

import static org.robolectric.RuntimeEnvironment.application;

import android.security.keystore.recovery.RecoveryController;

import com.android.server.backup.encryption.protos.nano.WrappedKeyProto;

import com.android.server.testing.shadows.ShadowRecoveryController;

import org.junit.Before;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.mockito.InOrder;

import org.mockito.Mock;

import org.mockito.MockitoAnnotations;

import org.robolectric.RobolectricTestRunner;

import org.robolectric.annotation.Config;

import java.security.SecureRandom;

import javax.crypto.SecretKey;

@RunWith(RobolectricTestRunner.class)

@Config(shadows = ShadowRecoveryController.class)

public class TertiaryKeyManagerTest {

    private static final String TEST_PACKAGE_1 = "com.example.app1";

    private static final String TEST_PACKAGE_2 = "com.example.app2";

    private SecureRandom mSecureRandom;

    private RecoverableKeyStoreSecondaryKey mSecondaryKey;

    @Mock private TertiaryKeyRotationScheduler mTertiaryKeyRotationScheduler;

    @Before

    public void setUp() throws Exception {

        MockitoAnnotations.initMocks(this);

        mSecureRandom = new SecureRandom();

        mSecondaryKey =

                new RecoverableKeyStoreSecondaryKeyManager(

                                RecoveryController.getInstance(application), mSecureRandom)

                        .generate();

        ShadowRecoveryController.reset();

    }

    private TertiaryKeyManager createNewManager(String packageName) {

        return new TertiaryKeyManager(

                application,

                mSecureRandom,

                mTertiaryKeyRotationScheduler,

                mSecondaryKey,

                packageName);

    }

    @Test

    public void getKey_noExistingKey_returnsNewKey() throws Exception {

        assertThat(createNewManager(TEST_PACKAGE_1).getKey()).isNotNull();

    }

    @Test

    public void getKey_noExistingKey_recordsIncrementalBackup() throws Exception {

        createNewManager(TEST_PACKAGE_1).getKey();

        verify(mTertiaryKeyRotationScheduler).recordBackup(TEST_PACKAGE_1);

    }

    @Test

    public void getKey_existingKey_returnsExistingKey() throws Exception {

        TertiaryKeyManager manager = createNewManager(TEST_PACKAGE_1);

        SecretKey existingKey = manager.getKey();

        assertThat(manager.getKey()).isEqualTo(existingKey);

    }

    @Test

    public void getKey_existingKey_recordsBackupButNotRotation() throws Exception {

        createNewManager(TEST_PACKAGE_1).getKey();

        reset(mTertiaryKeyRotationScheduler);

        createNewManager(TEST_PACKAGE_1).getKey();

        verify(mTertiaryKeyRotationScheduler).recordBackup(TEST_PACKAGE_1);

        verify(mTertiaryKeyRotationScheduler, never()).recordKeyRotation(any());

    }

    @Test

    public void getKey_existingKeyButRotationRequired_returnsNewKey() throws Exception {

        SecretKey firstKey = createNewManager(TEST_PACKAGE_1).getKey();

        when(mTertiaryKeyRotationScheduler.isKeyRotationDue(TEST_PACKAGE_1)).thenReturn(true);

        SecretKey secondKey = createNewManager(TEST_PACKAGE_1).getKey();

        assertThat(secondKey).isNotEqualTo(firstKey);

    }

    @Test

    public void getKey_existingKeyButRotationRequired_recordsKeyRotationAndBackup()

            throws Exception {

        when(mTertiaryKeyRotationScheduler.isKeyRotationDue(TEST_PACKAGE_1)).thenReturn(true);

        createNewManager(TEST_PACKAGE_1).getKey();

        InOrder inOrder = inOrder(mTertiaryKeyRotationScheduler);

        inOrder.verify(mTertiaryKeyRotationScheduler).recordKeyRotation(TEST_PACKAGE_1);

        inOrder.verify(mTertiaryKeyRotationScheduler).recordBackup(TEST_PACKAGE_1);

    }

    @Test

    public void getKey_twoApps_returnsDifferentKeys() throws Exception {

        TertiaryKeyManager firstManager = createNewManager(TEST_PACKAGE_1);

        TertiaryKeyManager secondManager = createNewManager(TEST_PACKAGE_2);

        SecretKey firstKey = firstManager.getKey();

        assertThat(secondManager.getKey()).isNotEqualTo(firstKey);

    }

    @Test

    public void getWrappedKey_noExistingKey_returnsWrappedNewKey() throws Exception {

        TertiaryKeyManager manager = createNewManager(TEST_PACKAGE_1);

        SecretKey unwrappedKey = manager.getKey();

        WrappedKeyProto.WrappedKey wrappedKey = manager.getWrappedKey();

        SecretKey expectedUnwrappedKey =

                KeyWrapUtils.unwrap(mSecondaryKey.getSecretKey(), wrappedKey);

        assertThat(unwrappedKey).isEqualTo(expectedUnwrappedKey);

    }

    @Test

    public void getWrappedKey_existingKey_returnsWrappedExistingKey() throws Exception {

        TertiaryKeyManager manager = createNewManager(TEST_PACKAGE_1);

        WrappedKeyProto.WrappedKey wrappedKey = manager.getWrappedKey();

        SecretKey unwrappedKey = manager.getKey();

        SecretKey expectedUnwrappedKey =

                KeyWrapUtils.unwrap(mSecondaryKey.getSecretKey(), wrappedKey);

        assertThat(unwrappedKey).isEqualTo(expectedUnwrappedKey);

    }

    @Test

    public void wasKeyRotated_noExistingKey_returnsTrue() throws Exception {

        TertiaryKeyManager manager = createNewManager(TEST_PACKAGE_1);

        assertThat(manager.wasKeyRotated()).isTrue();

    }

    @Test

    public void wasKeyRotated_existingKey_returnsFalse() throws Exception {

        createNewManager(TEST_PACKAGE_1).getKey();

        assertThat(createNewManager(TEST_PACKAGE_1).wasKeyRotated()).isFalse();

    }

}