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
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/*
* Copyright (C) 2017, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.util.sha1;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import static org.junit.Assume.assumeTrue;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.util.IO;
import org.junit.Test;
public class SHA1Test {
private static final String TEST1 = "abc";
private static final String TEST2a = "abcdbcdecdefdefgefghfghighijhi";
private static final String TEST2b = "jkijkljklmklmnlmnomnopnopq";
private static final String TEST2 = TEST2a + TEST2b;
@Test
public void test0() throws NoSuchAlgorithmException {
ObjectId exp = ObjectId
.fromString("da39a3ee5e6b4b0d3255bfef95601890afd80709");
MessageDigest m = MessageDigest.getInstance("SHA-1");
m.update(new byte[] {});
ObjectId m1 = ObjectId.fromRaw(m.digest());
SHA1 s = SHA1.newInstance();
s.update(new byte[] {});
ObjectId s1 = ObjectId.fromRaw(s.digest());
s.reset();
s.update(new byte[] {});
ObjectId s2 = s.toObjectId();
assertEquals(m1, s1);
assertEquals(exp, s1);
assertEquals(exp, s2);
}
@Test
public void test1() throws NoSuchAlgorithmException {
ObjectId exp = ObjectId
.fromString("a9993e364706816aba3e25717850c26c9cd0d89d");
MessageDigest m = MessageDigest.getInstance("SHA-1");
m.update(TEST1.getBytes(UTF_8));
ObjectId m1 = ObjectId.fromRaw(m.digest());
SHA1 s = SHA1.newInstance();
s.update(TEST1.getBytes(UTF_8));
ObjectId s1 = ObjectId.fromRaw(s.digest());
s.reset();
s.update(TEST1.getBytes(UTF_8));
ObjectId s2 = s.toObjectId();
assertEquals(m1, s1);
assertEquals(exp, s1);
assertEquals(exp, s2);
}
@Test
public void test2() throws NoSuchAlgorithmException {
ObjectId exp = ObjectId
.fromString("84983e441c3bd26ebaae4aa1f95129e5e54670f1");
MessageDigest m = MessageDigest.getInstance("SHA-1");
m.update(TEST2.getBytes(UTF_8));
ObjectId m1 = ObjectId.fromRaw(m.digest());
SHA1 s = SHA1.newInstance();
s.update(TEST2.getBytes(UTF_8));
ObjectId s1 = ObjectId.fromRaw(s.digest());
s.reset();
s.update(TEST2.getBytes(UTF_8));
ObjectId s2 = s.toObjectId();
assertEquals(m1, s1);
assertEquals(exp, s1);
assertEquals(exp, s2);
}
@Test
public void shatteredCollision()
throws IOException, NoSuchAlgorithmException {
byte[] pdf1 = read("shattered-1.pdf", 422435);
byte[] pdf2 = read("shattered-2.pdf", 422435);
MessageDigest md;
SHA1 s;
// SHAttered attack generated these PDFs to have identical SHA-1.
ObjectId bad = ObjectId
.fromString("38762cf7f55934b34d179ae6a4c80cadccbb7f0a");
md = MessageDigest.getInstance("SHA-1");
md.update(pdf1);
assertEquals("shattered-1 collides", bad,
ObjectId.fromRaw(md.digest()));
s = SHA1.newInstance().setDetectCollision(false);
s.update(pdf1);
assertEquals("shattered-1 collides", bad, s.toObjectId());
md = MessageDigest.getInstance("SHA-1");
md.update(pdf2);
assertEquals("shattered-2 collides", bad,
ObjectId.fromRaw(md.digest()));
s = SHA1.newInstance().setDetectCollision(false);
s.update(pdf2);
assertEquals("shattered-2 collides", bad, s.toObjectId());
// SHA1 with detectCollision shouldn't be fooled.
s = SHA1.newInstance().setDetectCollision(true);
s.update(pdf1);
try {
s.digest();
fail("expected " + Sha1CollisionException.class.getSimpleName());
} catch (Sha1CollisionException e) {
assertEquals(e.getMessage(),
"SHA-1 collision detected on " + bad.name());
}
s = SHA1.newInstance().setDetectCollision(true);
s.update(pdf2);
try {
s.digest();
fail("expected " + Sha1CollisionException.class.getSimpleName());
} catch (Sha1CollisionException e) {
assertEquals(e.getMessage(),
"SHA-1 collision detected on " + bad.name());
}
}
@Test
public void shatteredStoredInGitBlob() throws IOException {
byte[] pdf1 = read("shattered-1.pdf", 422435);
byte[] pdf2 = read("shattered-2.pdf", 422435);
// Although the prior test detects the chance of a collision, adding
// the Git blob header permutes the data enough for this specific
// attack example to not be detected as a collision. (A different file
// pair that takes the Git header into account however, would.)
ObjectId id1 = blob(pdf1, SHA1.newInstance().setDetectCollision(true));
ObjectId id2 = blob(pdf2, SHA1.newInstance().setDetectCollision(true));
assertEquals(
ObjectId.fromString("ba9aaa145ccd24ef760cf31c74d8f7ca1a2e47b0"),
id1);
assertEquals(
ObjectId.fromString("b621eeccd5c7edac9b7dcba35a8d5afd075e24f2"),
id2);
}
@Test
public void detectsShatteredByDefault() throws IOException {
assumeTrue(System.getProperty("org.eclipse.jgit.util.sha1.detectCollision") == null);
assumeTrue(System.getProperty("org.eclipse.jgit.util.sha1.safeHash") == null);
byte[] pdf1 = read("shattered-1.pdf", 422435);
SHA1 s = SHA1.newInstance();
s.update(pdf1);
try {
s.digest();
fail("expected " + Sha1CollisionException.class.getSimpleName());
} catch (Sha1CollisionException e) {
assertTrue("shattered-1 detected", true);
}
}
private static ObjectId blob(byte[] pdf1, SHA1 s) {
s.update(Constants.encodedTypeString(Constants.OBJ_BLOB));
s.update((byte) ' ');
s.update(Constants.encodeASCII(pdf1.length));
s.update((byte) 0);
s.update(pdf1);
return s.toObjectId();
}
private byte[] read(String name, int sizeHint) throws IOException {
try (InputStream in = getClass().getResourceAsStream(name)) {
ByteBuffer buf = IO.readWholeStream(in, sizeHint);
byte[] r = new byte[buf.remaining()];
buf.get(r);
return r;
}
}
}
|
