| /* |
| * Copyright (C) 2018 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 java.security.NoSuchAlgorithmException; |
| import java.security.SecureRandom; |
| |
| import javax.crypto.KeyGenerator; |
| import javax.crypto.SecretKey; |
| |
| /** 256-bit AES key generator. Each app should have its own separate AES key. */ |
| public class TertiaryKeyGenerator { |
| private static final int KEY_SIZE_BITS = 256; |
| private static final String KEY_ALGORITHM = "AES"; |
| |
| private final KeyGenerator mKeyGenerator; |
| |
| /** New instance generating keys using {@code secureRandom}. */ |
| public TertiaryKeyGenerator(SecureRandom secureRandom) { |
| try { |
| mKeyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM); |
| mKeyGenerator.init(KEY_SIZE_BITS, secureRandom); |
| } catch (NoSuchAlgorithmException e) { |
| throw new AssertionError( |
| "Impossible condition: JCE thinks it does not support AES.", e); |
| } |
| } |
| |
| /** Generates a new random AES key. */ |
| public SecretKey generate() { |
| return mKeyGenerator.generateKey(); |
| } |
| } |