1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.apkzlib.sign;
import com.android.annotations.NonNull;
/**
* Message digest algorithms.
*/
public enum DigestAlgorithm {
/**
* SHA-1 digest.
* <p>
* Android 2.3 (API Level 9) to 4.2 (API Level 17) (inclusive) do not support SHA-2
* JAR signatures.
* <p>
* Moreover, platforms prior to API Level 18, without the additional
* Digest-Algorithms attribute, only support SHA or SHA1 algorithm names in .SF and
* MANIFEST.MF attributes.
*/
SHA1("SHA1", "SHA-1"),
/**
* SHA-256 digest.
*/
SHA256("SHA-256", "SHA-256");
/**
* API level which supports {@link #SHA256} with {@link SignatureAlgorithm#RSA}.
*/
public static final int API_SHA_256_RSA = 18;
/**
* API level which supports {@link #SHA256} for all {@link SignatureAlgorithm}s.
*
* <p>Before that, SHA256 can only be used with RSA.
*/
public static final int API_SHA_256_ALL_ALGORITHMS = 21;
/**
* Name of algorithm for message digest.
*/
@NonNull
public final String messageDigestName;
/**
* Name of attribute in signature file with the manifest digest.
*/
@NonNull
public final String manifestAttributeName;
/**
* Name of attribute in entry (both manifest and signature file) with the entry's digest.
*/
@NonNull
public final String entryAttributeName;
/**
* Creates a digest algorithm.
*
* @param attributeName attribute name in the signature file
* @param messageDigestName name of algorithm for message digest
*/
DigestAlgorithm(@NonNull String attributeName, @NonNull String messageDigestName) {
this.messageDigestName = messageDigestName;
this.entryAttributeName = attributeName + "-Digest";
this.manifestAttributeName = attributeName + "-Digest-Manifest";
}
/**
* Finds the best digest algorithm applicable for a given SDK.
*
* @param minSdk the minimum SDK
* @param signatureAlgorithm signature algorithm used
* @return the best algorithm found
*/
@NonNull
public static DigestAlgorithm findBest(
int minSdk,
@NonNull SignatureAlgorithm signatureAlgorithm) {
if (signatureAlgorithm == SignatureAlgorithm.RSA) {
// PKCS #7 RSA signatures with SHA-256 are
// supported only since API Level 18 (JB MR2).
return minSdk >= API_SHA_256_RSA ? SHA256 : SHA1;
} else {
// PKCS #7 ECDSA and DSA signatures with SHA-256
// are supported only since API Level 21 (Android L).
return minSdk >= API_SHA_256_ALL_ALGORITHMS ? SHA256 : SHA1;
}
}
}
|
