0VFdZ46i

1import java.io.BufferedInputStream;
2import java.io.FileInputStream;
3import java.io.IOException;
4import java.security.DigestInputStream;
5import javax.crypto.Mac;
6import java.security.MessageDigest;
7import java.security.NoSuchAlgorithmException;
8import javax.crypto.KeyGenerator;
9import javax.crypto.SecretKey;
10import java.security.InvalidKeyException;
11
12public class TestDigest {
13
14    /**
15     * Generate the MessageDigest from a string
16     * @param the string
17     * @return the digest of the string
18     */
19    public byte[] testMessageDigest(String str) 
20            throws NoSuchAlgorithmException 
21    {
22        MessageDigest md = MessageDigest.getInstance("MD5");
23        md.update(str.getBytes());
24        return md.digest();
25    }
26    
27    public byte[] testMac(String str, SecretKey key) 
28            throws NoSuchAlgorithmException, InvalidKeyException
29    {
30        Mac md = Mac.getInstance("HmacMD5");
31        md.init(key);
32        md.update(str.getBytes());
33        return md.doFinal();
34    }
35
36    /**
37     * Generate the MessageDigest of a file
38     * @param the filename
39     * @return the digest of the file
40     */
41    public byte[] testDigestInputStream(String file) 
42            throws IOException,NoSuchAlgorithmException 
43    {
44        // other values: "SHA", "MD5", "SHA-384", "SHA-512", "MD2"
45        MessageDigest md = MessageDigest.getInstance("SHA");
46        
47        BufferedInputStream in = 
48                new BufferedInputStream(
49                new DigestInputStream(
50                new FileInputStream(file),md));
51        
52        int c;
53        
54        while((c = in.read()) != -1);
55        
56        return md.digest();
57    }
58    
59    /**
60     * Print a byte array in hexadecimal form
61     * @param the byte array
62     */
63    public static void printHexadecimal(byte[] bytes)
64    {
65        for(int i=0; i<bytes.length; i++)
66            System.out.printf("%X",bytes[i]);
67    }
68    
69    public static void main(String args[]) throws Exception 
70    {
71        String fileTest = "/etc/passwd";
72        String stringTest = "How can I believe in God when just last week I " +
73                "got my tongue caught in the roller of an electric typewriter?";
74        
75        TestDigest td = new TestDigest();
76        
77        // Print the digest of a test string
78        System.out.print("String: " + stringTest +"\n" + "String Digest:");
79        td.printHexadecimal(td.testMessageDigest(stringTest));
80        System.out.println();
81        
82        // Print the digest of a test file
83        System.out.print("File: " + fileTest +"\n" + "File Digest:");
84        td.printHexadecimal(td.testDigestInputStream(fileTest));
85        System.out.println();
86
87        // Print the digest of a test file
88        System.out.print("File MAC:");
89        KeyGenerator keyGen = KeyGenerator.getInstance("HmacMD5");
90        SecretKey key = keyGen.generateKey();
91        System.out.println("Key:");
92        printHexadecimal(key.getEncoded());
93        System.out.println();
94
95        System.out.println("MAC:");
96        td.printHexadecimal(td.testMac(stringTest,key));
97        System.out.println();
98
99    }
100}