-
Notifications
You must be signed in to change notification settings - Fork 0
/
CertificateBreak.java
111 lines (87 loc) · 2.73 KB
/
CertificateBreak.java
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
//credit to https://web.archive.org/web/20110516145331/http://weblogs.java.net/blog/pat/archive/2004/10/stupid_scanner.html for file to string
import java.util.Random;
import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
/**
* Given an original file and a 'malicious' file, CertificateBreak trivially
* modifies the 'malicious' file so that the java hashCode() of each file is
* identical.
*/
public class CertificateBreak {
public static void main(String args[]) {
String data = "";
String malicious = "";
String dataFile = "hello.py";
String malFile = "malicious.py";
if(args.length == 0) {
System.out.println("No parameters specified, using default files");
} else if(args.length == 2) {
dataFile = args[0];
malFile = args[1];
} else {
System.out.println("Incorrect usage, exiting program. Correct usage:");
System.out.println("\tjava CertificateBreak (original file) " +
"('malicious' file)");
System.out.println("If no parameters are specified, the default files " +
"are used. (hello.py and malicious.py)");
return;
}
try {
data = new Scanner(new File(dataFile)).useDelimiter("\\A").next();
malicious = new Scanner(new File(malFile)).useDelimiter("\\A").next();
} catch(FileNotFoundException e) {
e.printStackTrace();
System.out.println("File not found. Check spelling and location of " +
"file. Exiting.");
return;
}
String comment = getCommentCode(malFile);
Random r = new Random();
int cert = data.hashCode();
int fakeCert = malicious.hashCode();
String junkData = "";
System.out.print("Generating file...");
while(true) {
//generate string with 150 +/- 50 characters
for(int j = 0; j < r.nextInt(100) + 100; j++) {
// generate random string, hash the string
junkData += (char)(r.nextInt(74) + '0');
fakeCert = (malicious + comment + junkData).hashCode();
}
if(cert == fakeCert) {
System.out.println(" done.");
break;
}
junkData = "";
}
String finalFile = malicious + comment + junkData;
System.out.println("\n\n" + finalFile);
System.out.println("\n\nOriginal hash: " + data.hashCode());
System.out.println("Generated file hash: " + finalFile.hashCode());
}
/**
* From a filename's extension, determine he string needed to initiate a
* comment.
*/
public static String getCommentCode(String filename) {
String ext = filename.substring(filename.lastIndexOf('.'),
filename.length());
switch(ext) {
case ".py":
case ".rb":
return "#";
case ".c":
case ".h":
case ".java":
case ".cpp":
case ".hpp":
case ".cxx":
case ".js":
case ".cs":
case ".go":
return "//";
}
return "";
}
}