xWwEWQc9

1package ru.psqq;
2
3import javax.crypto.Cipher;
4import javax.crypto.spec.IvParameterSpec;
5import javax.crypto.spec.SecretKeySpec;
6import java.io.*;
7import java.security.Key;
8import java.security.MessageDigest;
9import java.util.Base64;
10
11public class Main {
12
13    private static final String ALGORITHM = "AES";
14    private static final String TRANSFORMATION = "AES";
15
16    private static final String KEY = "ZZHHYYTTUUHHGGRR";
17    private static final String IV = "AAACCCDDDYYUURRS";
18
19    public static void main(String[] args) {
20        try {
21            test_encrypt_decrypt();
22        } catch (Exception e) {
23            System.out.println("Error: " + e.getMessage());
24            System.exit(1);
25        }
26    }
27
28    public static void test_encrypt_decrypt() throws Exception {
29        // encrypt "in.txt" -> "out.txt"
30        String s = readFile("in.txt");
31        String res = encrypt("mykey", IV, s);
32        PrintWriter writer = new PrintWriter("out.txt", "UTF-8");
33        writer.print(res);
34        writer.close();
35        // decrypt "out.txt" -> "out2.txt"
36        s = readFile("out.txt");
37        res = decrypt("mykey", IV, s);
38        writer = new PrintWriter("out2.txt", "UTF-8");
39        writer.print(res);
40        writer.close();
41    }
42
43    public static String encrypt(String key, String iv, String msg) throws Exception {
44        byte[] bytesOfKey = key.getBytes("UTF-8");
45        MessageDigest md = MessageDigest.getInstance("MD5");
46        byte[] keyBytes = md.digest(bytesOfKey);
47
48        final byte[] ivBytes = iv.getBytes();
49
50        SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
51        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
52        cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, new IvParameterSpec(ivBytes));
53
54        final byte[] resultBytes = cipher.doFinal(msg.getBytes());
55        return Base64.getMimeEncoder().encodeToString(resultBytes);
56    }
57
58    public static void test_decrypt() throws Exception {
59        String s = readFile("in.txt");
60        String res = decrypt(KEY, IV, s);
61        System.out.println("res:\n" + res);
62    }
63
64    public static String decrypt(String key, String iv, String encrypted) throws Exception {
65        byte[] bytesOfKey = key.getBytes("UTF-8");
66        MessageDigest md = MessageDigest.getInstance("MD5");
67        byte[] keyBytes = md.digest(bytesOfKey);
68
69        final byte[] ivBytes = iv.getBytes();
70
71        final byte[] encryptedBytes = Base64.getMimeDecoder().decode(encrypted);
72
73        SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
74        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
75        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, new IvParameterSpec(ivBytes));
76
77        final byte[] resultBytes = cipher.doFinal(encryptedBytes);
78        return new String(resultBytes);
79    }
80
81    public static String readFile(String filename) throws Exception {
82        BufferedReader br = new BufferedReader(new FileReader(filename));
83        try {
84            StringBuilder sb = new StringBuilder();
85            String line = br.readLine();
86            while (line != null) {
87                sb.append(line);
88                sb.append(System.lineSeparator());
89                line = br.readLine();
90            }
91            String everything = sb.toString();
92            return everything;
93        } finally {
94            br.close();
95        }
96    }
97
98    public static void test_read_file() throws Exception {
99        String s = readFile("in.txt");
100        System.out.println("in.txt:\n" + s);
101    }
102
103    public static void encrypt(String key, File inputFile, File outputFile) throws Exception {
104        doCrypto(Cipher.ENCRYPT_MODE, key, inputFile, outputFile);
105    }
106
107    public static void decrypt(String key, File inputFile, File outputFile) throws Exception {
108        doCrypto(Cipher.DECRYPT_MODE, key, inputFile, outputFile);
109    }
110
111    static void doCrypto(int cipherMode, String key, File inputFile,
112                          File outputFile) throws Exception {
113        Key secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
114        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
115        cipher.init(cipherMode, secretKey);
116
117        FileInputStream inputStream = new FileInputStream(inputFile);
118        byte[] inputBytes = new byte[(int) inputFile.length()];
119        inputStream.read(inputBytes);
120
121        byte[] outputBytes = cipher.doFinal(inputBytes);
122
123        FileOutputStream outputStream = new FileOutputStream(outputFile);
124        outputStream.write(outputBytes);
125
126        inputStream.close();
127        outputStream.close();
128    }
129
130    public static void test_doCrypto(String filename) throws Exception {
131        String key = "Mary has one cat";
132        File inputFile = new File("document.txt");
133        File encryptedFile = new File("document.encrypted");
134        File decryptedFile = new File("document.decrypted");
135
136        encrypt(key, inputFile, encryptedFile);
137        decrypt(key, encryptedFile, decryptedFile);
138    }
139
140    public static void test_write_to_file(String filename) throws Exception {
141        PrintWriter writer = new PrintWriter(filename, "UTF-8");
142        writer.println("The first line");
143        writer.println("The second line");
144        writer.close();
145    }
146}