1 /*
2  * Copyright (C) 2016 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.apksig.internal.apk.v1;
18 
19 import java.util.Comparator;
20 
21 /**
22  * Digest algorithm used with JAR signing (aka v1 signing scheme).
23  */
24 public enum DigestAlgorithm {
25     /** SHA-1 */
26     SHA1("SHA-1"),
27 
28     /** SHA2-256 */
29     SHA256("SHA-256");
30 
31     private final String mJcaMessageDigestAlgorithm;
32 
DigestAlgorithm(String jcaMessageDigestAlgoritm)33     private DigestAlgorithm(String jcaMessageDigestAlgoritm) {
34         mJcaMessageDigestAlgorithm = jcaMessageDigestAlgoritm;
35     }
36 
37     /**
38      * Returns the {@link java.security.MessageDigest} algorithm represented by this digest
39      * algorithm.
40      */
getJcaMessageDigestAlgorithm()41     String getJcaMessageDigestAlgorithm() {
42         return mJcaMessageDigestAlgorithm;
43     }
44 
45     public static Comparator<DigestAlgorithm> BY_STRENGTH_COMPARATOR = new StrengthComparator();
46 
47     private static class StrengthComparator implements Comparator<DigestAlgorithm> {
48         @Override
compare(DigestAlgorithm a1, DigestAlgorithm a2)49         public int compare(DigestAlgorithm a1, DigestAlgorithm a2) {
50             switch (a1) {
51                 case SHA1:
52                     switch (a2) {
53                         case SHA1:
54                             return 0;
55                         case SHA256:
56                             return -1;
57                     }
58                     throw new RuntimeException("Unsupported algorithm: " + a2);
59 
60                 case SHA256:
61                     switch (a2) {
62                         case SHA1:
63                             return 1;
64                         case SHA256:
65                             return 0;
66                     }
67                     throw new RuntimeException("Unsupported algorithm: " + a2);
68 
69                 default:
70                     throw new RuntimeException("Unsupported algorithm: " + a1);
71             }
72         }
73     }
74 }
75