1/*
2 * Copyright (C) 2017 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
17package android.security.keystore.recovery;
18
19import android.annotation.NonNull;
20import android.os.Parcel;
21import android.os.Parcelable;
22
23import com.android.internal.util.Preconditions;
24
25import java.io.ByteArrayInputStream;
26import java.security.cert.CertPath;
27import java.security.cert.CertificateEncodingException;
28import java.security.cert.CertificateException;
29import java.security.cert.CertificateFactory;
30
31/**
32 * The certificate path of the recovery service.
33 *
34 * @hide
35 */
36public final class RecoveryCertPath implements Parcelable {
37
38    private static final String CERT_PATH_ENCODING = "PkiPath";
39
40    private final byte[] mEncodedCertPath;
41
42    /**
43     * Wraps a {@code CertPath} to create a {@code Parcelable} for Binder calls.
44     *
45     * @param certPath The certificate path to be wrapped.
46     * @throws CertificateException if the given certificate path cannot be encoded properly.
47     */
48    public static @NonNull RecoveryCertPath createRecoveryCertPath(@NonNull CertPath certPath)
49            throws CertificateException {
50        // Perform the encoding here to avoid throwing exceptions in writeToParcel
51        try {
52            return new RecoveryCertPath(encodeCertPath(certPath));
53        } catch (CertificateEncodingException e) {
54            throw new CertificateException("Failed to encode the given CertPath", e);
55        }
56    }
57
58    /**
59     * Obtains the {@code CertPath} wrapped in the Parcelable.
60     *
61     * @return the wrapped certificate path.
62     * @throws CertificateException if the wrapped certificate path cannot be decoded properly.
63     */
64    public @NonNull CertPath getCertPath() throws CertificateException {
65        // Perform the decoding here to avoid throwing exceptions in createFromParcel
66        return decodeCertPath(mEncodedCertPath);
67    }
68
69    private RecoveryCertPath(@NonNull byte[] encodedCertPath) {
70        mEncodedCertPath = Preconditions.checkNotNull(encodedCertPath);
71    }
72
73    private RecoveryCertPath(Parcel in) {
74        mEncodedCertPath = in.createByteArray();
75    }
76
77    public static final Parcelable.Creator<RecoveryCertPath> CREATOR =
78            new Parcelable.Creator<RecoveryCertPath>() {
79        public RecoveryCertPath createFromParcel(Parcel in) {
80            return new RecoveryCertPath(in);
81        }
82
83        public RecoveryCertPath[] newArray(int length) {
84            return new RecoveryCertPath[length];
85        }
86    };
87
88    @Override
89    public void writeToParcel(Parcel out, int flags) {
90        out.writeByteArray(mEncodedCertPath);
91    }
92
93    @Override
94    public int describeContents() {
95        return 0;
96    }
97
98    @NonNull
99    private static byte[] encodeCertPath(@NonNull CertPath certPath)
100            throws CertificateEncodingException {
101        Preconditions.checkNotNull(certPath);
102        return certPath.getEncoded(CERT_PATH_ENCODING);
103    }
104
105    @NonNull
106    private static CertPath decodeCertPath(@NonNull byte[] bytes) throws CertificateException {
107        Preconditions.checkNotNull(bytes);
108        CertificateFactory certFactory;
109        try {
110            certFactory = CertificateFactory.getInstance("X.509");
111        } catch (CertificateException e) {
112            // Should not happen, as X.509 is mandatory for all providers.
113            throw new RuntimeException(e);
114        }
115        return certFactory.generateCertPath(new ByteArrayInputStream(bytes), CERT_PATH_ENCODING);
116    }
117}
118