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      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 
     17 package android.security.keystore.recovery;
     18 
     19 import android.annotation.NonNull;
     20 import android.os.Parcel;
     21 import android.os.Parcelable;
     22 
     23 import com.android.internal.util.Preconditions;
     24 
     25 import java.io.ByteArrayInputStream;
     26 import java.security.cert.CertPath;
     27 import java.security.cert.CertificateEncodingException;
     28 import java.security.cert.CertificateException;
     29 import java.security.cert.CertificateFactory;
     30 
     31 /**
     32  * The certificate path of the recovery service.
     33  *
     34  * @hide
     35  */
     36 public 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