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1package sample;
2
3import javax.crypto.Cipher;
4import javax.crypto.spec.IvParameterSpec;
5import javax.crypto.spec.SecretKeySpec;
6import java.nio.ByteBuffer;
7import java.security.SecureRandom;
8import java.util.Arrays;
9import java.util.Random;
10
11public class AesCipher {
12
13//    private static final String INIT_VECTOR = "ItIsOurBigSecret";
14//    private static final String INIT_VECTOR = "dfgthyjukifredsr";
15
16    // зашифрование
17    static byte[] encrypt(byte[] secretKey, byte[] plainText, String mode) {
18
19        try {
20            if (!isKeyLengthValid(secretKey)) {
21                throw new Exception("Длина ключа должна быть 128, 192 или 256 бит!");
22            }
23
24//            IvParameterSpec ivParameterSpec = new IvParameterSpec(INIT_VECTOR.getBytes());
25            SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey, "AES");
26
27            Cipher cipher = Cipher.getInstance("AES/" + mode + "/PKCS5Padding");
28
29            SecureRandom secureRandom = new SecureRandom();
30            byte[] iv = new byte[cipher.getBlockSize()];
31            secureRandom.nextBytes(iv);
32            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
33
34            if (mode.equals("ECB"))
35                cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
36            else
37                cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
38
39            byte[] c = cipher.doFinal(plainText);
40
41//            return cipher.doFinal(plainText);
42            return ByteBuffer.wrap(new byte[iv.length + c.length]).put(iv).put(c).array();
43        } catch (Throwable cause) {
44            System.out.print(cause.getMessage());
45        }
46
47        return null;
48    }
49
50
51    // дешифрование
52    static byte[] decrypt(byte[] secretKey, byte[] cipherText, String mode) {
53
54        try {
55            if (!isKeyLengthValid(secretKey)) {
56                throw new Exception("Длина ключа должна быть 128, 192 или 256 бит!");
57            }
58
59//            IvParameterSpec ivParameterSpec = new IvParameterSpec(INIT_VECTOR.getBytes());
60            SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey, "AES");
61
62            Cipher cipher = Cipher.getInstance("AES/" + mode + "/NoPadding");
63
64            byte[] iv = new byte[cipher.getBlockSize()];
65            System.arraycopy(cipherText, 0, iv, 0, iv.length);
66            IvParameterSpec ivParameterSpec = new IvParameterSpec(iv);
67
68            if (mode.equals("ECB"))
69                cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
70            else
71                cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);
72
73            byte[] cipherTextNew = new byte[cipherText.length - iv.length];
74            System.arraycopy(cipherText, 15, cipherTextNew, 0, cipherTextNew.length);
75
76            return cipher.doFinal(cipherTextNew);
77        } catch (Throwable cause) {
78            System.out.print(cause.getMessage());
79            Controller.ShowMessage(cause.getMessage());
80        }
81
82        return null;
83    }
84
85
86    // проверка длины ключа
87    private static boolean isKeyLengthValid(byte[] key) {
88        return key.length == 16 || key.length == 24 || key.length == 32;
89    }
90
91
92    // генерация инициализирующего вектора
93    private static String genInitVector() {
94
95        Random r = new Random();
96        StringBuilder builder = new StringBuilder();
97
98        for (int j = 0; j < 16; j++) {
99            char code = (char) (r.nextInt(94) + 33); // символы с кодами от 33 по 126
100            builder.append(Character.toString(code));
101        }
102
103        return builder.toString();
104    }
105
106}