1 /* 2 * Copyright (C) 2020 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.server.locksettings; 18 19 import java.io.IOException; 20 import java.security.NoSuchAlgorithmException; 21 import java.security.SecureRandom; 22 23 import javax.crypto.KeyGenerator; 24 import javax.crypto.SecretKey; 25 import javax.crypto.spec.SecretKeySpec; 26 27 /** 28 * Key used to encrypt and decrypt the {@link RebootEscrowData}. 29 */ 30 class RebootEscrowKey { 31 32 /** The secret key will be of this format. */ 33 private static final String KEY_ALGO = "AES"; 34 35 /** The key size used for encrypting the reboot escrow data. */ 36 private static final int KEY_SIZE_BITS = 256; 37 38 private final SecretKey mKey; 39 RebootEscrowKey(SecretKey key)40 private RebootEscrowKey(SecretKey key) { 41 mKey = key; 42 } 43 fromKeyBytes(byte[] keyBytes)44 static RebootEscrowKey fromKeyBytes(byte[] keyBytes) { 45 return new RebootEscrowKey(new SecretKeySpec(keyBytes, KEY_ALGO)); 46 } 47 generate()48 static RebootEscrowKey generate() throws IOException { 49 final SecretKey secretKey; 50 try { 51 KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_ALGO); 52 keyGenerator.init(KEY_SIZE_BITS, new SecureRandom()); 53 secretKey = keyGenerator.generateKey(); 54 } catch (NoSuchAlgorithmException e) { 55 throw new IOException("Could not generate new secret key", e); 56 } 57 return new RebootEscrowKey(secretKey); 58 } 59 getKey()60 SecretKey getKey() { 61 return mKey; 62 } 63 getKeyBytes()64 byte[] getKeyBytes() { 65 return mKey.getEncoded(); 66 } 67 } 68