PyW93HkT

1import java.net.*;
2import java.io.*;
3import javax.crypto.*;
4import javax.crypto.spec.IvParameterSpec;
5import javax.crypto.spec.SecretKeySpec;
6import java.security.*;
7
8public class Client {
9    public static void main(String args[]) {
10
11        Socket s = null;
12        int serversocket = 4567;
13        try {
14            s = new Socket("127.0.0.1", serversocket);
15
16            DataInputStream in = new DataInputStream(s.getInputStream());
17            DataOutputStream out = new DataOutputStream(s.getOutputStream());
18
19            while (true){
20                //key
21                byte [] key = {1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4};
22
23                //hash function and new keys
24                MessageDigest md = MessageDigest.getInstance("SHA-256");
25
26                byte [] byte1 = {1};
27                byte [] aux1 = concat(key, byte1);
28                byte [] hash1= md.digest(aux1);
29                SecretKey k1 = new SecretKeySpec(hash1, 0, hash1.length, "AES");
30
31                byte [] byte2 = {2};
32                byte [] aux2 = concat(key, byte2);
33                byte [] hash2= md.digest(aux2);
34                SecretKey k2 = new SecretKeySpec(hash2, 0, hash2.length, "HMAC");
35
36                //message authentication code
37                Mac mac = Mac.getInstance("HmacSHA256");
38                mac.init(k2);
39                int nSeq = 0;
40
41                //nonce - sends the bytes in plaintext so that the server can create the same IV
42                byte[] bytesForIV=new byte[16];
43                SecureRandom sr = new SecureRandom();
44                sr.nextBytes(bytesForIV);
45                IvParameterSpec iv = new IvParameterSpec(bytesForIV);
46                out.write(bytesForIV);
47
48                //E(m, k1) = c
49                Cipher c = Cipher.getInstance("AES/CTR/PKCS5Padding");
50                c.init(Cipher.ENCRYPT_MODE, k1, iv);
51
52
53                String text = "";
54                InputStreamReader input = new InputStreamReader(System.in);
55                BufferedReader reader = new BufferedReader(input);
56
57                while (true) {
58
59                    try {
60                        text = reader.readLine();
61
62
63                        byte [] enc = c.doFinal(text.getBytes());
64                        byte [] nSeqByte = intToByteArray(nSeq);
65
66                        byte [] authTagAux = concat(enc, nSeqByte);
67                        byte [] authTag = mac.doFinal(authTagAux);
68
69                        // pacote=[tamanho da ciphertext(4 bytes)][mac(32 bytes)][ciphertext]
70                        byte[] pacote=concat(intToByteArray(enc.length),concat(authTag,enc));
71                        out.write(pacote);
72                        nSeq++;
73
74                    }
75                    catch (Exception e) {
76
77                    }
78
79
80                }
81            }
82        } catch (UnknownHostException e) {
83            System.out.println("Sock:" + e.getMessage());
84        } catch (EOFException e) {
85            System.out.println("EOF:" + e.getMessage());
86        } catch (IOException e) {
87            System.out.println("IO:" + e.getMessage());
88        } catch (NoSuchPaddingException e) {
89            e.printStackTrace();
90        } catch (NoSuchAlgorithmException e) {
91            e.printStackTrace();
92        } catch (InvalidAlgorithmParameterException e) {
93            e.printStackTrace();
94        } catch (InvalidKeyException e) {
95            e.printStackTrace();
96
97        } finally {
98            if (s != null)
99                try {
100                    s.close();
101                } catch (IOException e) {
102                    System.out.println("close:" + e.getMessage());
103                }
104        }
105    }
106
107    private static byte [] concat(byte[] first, byte[] second) throws IOException {
108        ByteArrayOutputStream baos = new ByteArrayOutputStream();
109        baos.write(first);
110        baos.write(second);
111        byte [] result = baos.toByteArray();
112        baos.reset();
113        return result;
114    }
115
116    //https://stackoverflow.com/questions/2183240/java-integer-to-byte-array
117    public static final byte[] intToByteArray(int value) {
118        return new byte[]{
119                (byte)(value >>> 24),
120                (byte)(value >>> 16),
121                (byte)(value >>> 8),
122                (byte)value};
123    }
124}