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 android.security;
18 
19 import android.annotation.NonNull;
20 import android.hardware.security.keymint.HardwareAuthToken;
21 import android.hardware.security.secureclock.Timestamp;
22 
23 import java.nio.ByteBuffer;
24 import java.nio.ByteOrder;
25 
26 /**
27  * @hide This Utils class provides method(s) for AuthToken conversion.
28  */
29 public class AuthTokenUtils {
30 
AuthTokenUtils()31     private AuthTokenUtils(){
32     }
33 
34     /**
35      * Build a HardwareAuthToken from a byte array
36      * @param array byte array representing an auth token
37      * @return HardwareAuthToken representation of an auth token
38      */
toHardwareAuthToken(@onNull byte[] array)39     public static @NonNull HardwareAuthToken toHardwareAuthToken(@NonNull byte[] array) {
40         final HardwareAuthToken hardwareAuthToken = new HardwareAuthToken();
41 
42         // First byte is version, which does not exist in HardwareAuthToken anymore
43         // Next 8 bytes is the challenge.
44         hardwareAuthToken.challenge =
45                 ByteBuffer.wrap(array, 1, 8).order(ByteOrder.nativeOrder()).getLong();
46 
47         // Next 8 bytes is the userId
48         hardwareAuthToken.userId =
49                 ByteBuffer.wrap(array, 9, 8).order(ByteOrder.nativeOrder()).getLong();
50 
51         // Next 8 bytes is the authenticatorId.
52         hardwareAuthToken.authenticatorId =
53                 ByteBuffer.wrap(array, 17, 8).order(ByteOrder.nativeOrder()).getLong();
54 
55         // while the other fields are in machine byte order, authenticatorType and timestamp
56         // are in network byte order.
57         // Next 4 bytes is the authenticatorType.
58         hardwareAuthToken.authenticatorType =
59                 ByteBuffer.wrap(array, 25, 4).order(ByteOrder.BIG_ENDIAN).getInt();
60         // Next 8 bytes is the timestamp.
61         final Timestamp timestamp = new Timestamp();
62         timestamp.milliSeconds =
63                 ByteBuffer.wrap(array, 29, 8).order(ByteOrder.BIG_ENDIAN).getLong();
64         hardwareAuthToken.timestamp = timestamp;
65 
66         // Last 32 bytes is the mac, 37:69
67         hardwareAuthToken.mac = new byte[32];
68         System.arraycopy(array, 37 /* srcPos */,
69                 hardwareAuthToken.mac,
70                 0 /* destPos */,
71                 32 /* length */);
72 
73         return hardwareAuthToken;
74     }
75 }
76