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1package KrypteringPackage;
2
3import javax.crypto.*;
4import javax.crypto.spec.*;
5import java.security.*;
6import java.io.*;
7
8public class DecryptHandler {
9	
10	public static void main(String[] args) {
11		
12		if (args.length == 3)
13	{
14		String encryptedData = args[0];
15		String secretKeyLocation = args[1];
16		String decryptedData = args[2];
17
18        
19		byte[] data = null;
20		SecretKey secretKey = null;
21		
22		try {
23			FileInputStream fileIn = new FileInputStream(encryptedData); //lägger in krypterade datan i en byte[]
24	         ObjectInputStream objectIn = new ObjectInputStream(fileIn);
25	         data = (byte[]) objectIn.readObject();
26	         objectIn.close();
27	         fileIn.close();
28			}
29		 catch (IOException | ClassNotFoundException e1) {
30			e1.printStackTrace();
31		}
32		
33		try { // Binär deserializerar nyckeln eftersom det inte går att skriva det i plan text sen konvertera den till secretKey
34			
35			FileInputStream fileIn = new FileInputStream(secretKeyLocation);
36			
37	         ObjectInputStream objectIn = new ObjectInputStream(fileIn);
38	         secretKey = (SecretKey) objectIn.readObject();
39	         objectIn.close();
40	         fileIn.close();
41			}
42		 catch (IOException | ClassNotFoundException e1) {
43			e1.printStackTrace();
44		}
45		
46		data = encryptedData.getBytes();
47		byte[] decryptedDataWithKey = null;
48		
49        Cipher cipher;
50		try {
51
52			cipher = Cipher.getInstance("Blowfish/CBC/PKCS5Padding"); // algoritm som används
53	        cipher.init(Cipher.DECRYPT_MODE, secretKey); // väljer att man ska dekryptera
54
55	        decryptedDataWithKey = cipher.doFinal(data); //enkrypterade datan blir dekrypterad
56	        
57		} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException  e) {
58			e.printStackTrace();
59		} 
60		
61		
62	
63		Writer writer;
64		try { // Skriver den krypterade datan till en ny fil med namnet på encryptedData
65			writer = new BufferedWriter(new OutputStreamWriter(
66				    new FileOutputStream(decryptedData + ".txt"), "utf-8"));
67			writer.write(decryptedDataWithKey.toString());
68
69			writer.flush();
70			System.out.println("decrypted " + encryptedData + " to file " + decryptedData);
71			
72			writer.close();
73		} catch (IOException e) {
74			// TODO Auto-generated catch block
75			e.printStackTrace();
76			} 
77
78		
79	}
80		else
81		{
82			System.out.println("Incorrect Syntax. java EncryptHandler <encryptedData> <secretKey> <decryptetData>");
83		}
84	}
85}