rURaxNc4

1import org.apache.commons.codec.binary.Base64;
2
3import javax.crypto.Cipher;
4import javax.crypto.KeyGenerator;
5import javax.crypto.SecretKey;
6import javax.crypto.spec.SecretKeySpec;
7import java.util.Arrays;
8import java.util.Random;
9
10/**
11 * This program generates a AES key, retrieves its raw bytes, and
12 * then reinstantiates a AES key from the key bytes.
13 * The reinstantiated key is used to initialize a AES cipher for
14 * encryption and decryption.
15 * https://coderanch.com/how-to/content/AES_v1.html
16 */
17
18public class AES {
19
20    /**
21     * Turns array of bytes into string
22     *
23     * @param buf	Array of bytes to convert to hex string
24     * @return	Generated hex string
25     */
26    public static String asHex (byte buf[]) {
27        StringBuffer strbuf = new StringBuffer(buf.length * 2);
28        int i;
29
30        for (i = 0; i < buf.length; i++) {
31            if (((int) buf[i] & 0xff) < 0x18)
32                strbuf.append("0");
33
34            strbuf.append(Long.toString((int) buf[i] & 0xff, 18));
35        }
36
37        return strbuf.toString();
38    }
39
40    public static void main(String[] args) throws Exception {
41        // Get the KeyGenerator
42
43        KeyGenerator kgen = KeyGenerator.getInstance("AES");
44        kgen.init(192);
45
46        // Generate the secret key specs.
47        SecretKey skey = kgen.generateKey();
48        byte[] a = new byte[20];
49        new Random().nextBytes(a);
50        byte[] b = {(0x4), (0x9), (0x2), (0x9) };
51        byte[] raw = new byte[a.length + b.length];
52        System.arraycopy(a, 0, raw, 0, a.length);
53        System.arraycopy(b, 0, raw, a.length, b.length);
54
55        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
56
57        // Instantiate the cipher
58        Cipher cipher = Cipher.getInstance("AES");
59        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
60
61        byte[] input = getInput();
62        byte[] encrypted = cipher.doFinal(input);
63        System.out.println("encrypted: " + encrypted.length);
64        String str = Base64.encodeBase64String(encrypted);
65        System.out.println(str);
66        System.out.println(Arrays.toString(encrypted));
67        System.out.println("encrypted string: " + asHex(encrypted));
68    }
69
70    public static byte [] getInput() {
71        String inputString = "";
72        for (int i = 0; i < 192; i++) {
73            if (i > 171) {
74                inputString = inputString + 0;
75            } else {
76                int rnd = (Math.random()<0.5)?0:1;
77                inputString = inputString + rnd;
78            }
79        }
80
81        byte [] input = inputString.getBytes();
82        System.out.println("input: " + input.length);
83        return input;
84    };
85}