uSyWMfFM

1package cviko5;
2
3import java.security.NoSuchAlgorithmException;
4
5import javax.crypto.*;
6import javax.crypto.spec.IvParameterSpec;
7
8public class DES {
9
10	public static enum PBM {
11		PB_ASCII, PB_HEX, PB_HEX_UPPER;
12	};
13
14	public static final int PB_TAB = 8;
15	public static final int PB_LENGTH = 25;
16
17	public static void PrintBytes(byte[] bytes, PBM mode) {
18		String modestr;
19		switch (mode) {
20		case PB_ASCII:
21			modestr = "%c";
22			break;
23		case PB_HEX:
24			modestr = "%02x";
25			break;
26		case PB_HEX_UPPER:
27		default:
28			modestr = "%02X";
29		}
30		for (int ind = 0; ind < bytes.length; ind++) {
31			try {
32				System.out.printf(modestr, bytes[ind]);
33			} catch (Exception e) {
34				System.out.printf("%%%02X%%", bytes[ind]);
35			}
36			if ((ind + 1) % PB_LENGTH == 0)
37				System.out.println("\\");
38			else if ((ind + 1) % PB_TAB == 0)
39				System.out.print(" ");
40		}
41		System.out.println();
42	}
43
44	public static void main(String[] args) throws Exception {
45
46		String pole[] = { "DES/CBC/PKCS5Padding", "DES/OFB/PKCS5Padding", "DES/CFB/PKCS5Padding",
47				"DES/CFB32/PKCS5Padding", "DES/CFB8/PKCS5Padding" };
48
49		for (String s : pole) {
50			System.out.println(s);
51			System.out.println();
52			Cipher desCipher = Cipher.getInstance(s); // Create the cipher
53
54			KeyGenerator keygen = KeyGenerator.getInstance("DES");
55			SecretKey desKey = keygen.generateKey();
56			desCipher.init(Cipher.ENCRYPT_MODE, desKey); // Initialize the cipher for encryption; IvParameterSpec
57			byte[] iv = desCipher.getIV();
58
59			Cipher desCipher2 = Cipher.getInstance(s);
60
61			byte[] cleartext = "ABCDEFGHXXXXXXXXABCDEFGH".getBytes();
62			PrintBytes(cleartext, PBM.PB_ASCII);
63			byte[] ciphertext = desCipher.doFinal(cleartext); // Encrypt the cleartext
64			ciphertext[10] = (byte) (ciphertext[5] ^ 128);
65			PrintBytes(ciphertext, PBM.PB_HEX);
66
67			desCipher2.init(Cipher.DECRYPT_MODE, desKey, new IvParameterSpec(iv)); // Initialize the same cipher for
68																					// decryption
69			byte[] decryptedtext = desCipher2.doFinal(ciphertext); // Decrypt the ciphertext
70			PrintBytes(decryptedtext, PBM.PB_ASCII);
71			System.out.println();
72		}
73
74	}
75
76}