HCMsKUMg

1import java.net.*;
2import java.io.*;
3import java.nio.file.*;
4import java.security.InvalidAlgorithmParameterException;
5import java.security.InvalidKeyException;
6import java.security.NoSuchAlgorithmException;
7import java.security.SecureRandom;
8import javax.crypto.*;
9import javax.crypto.spec.IvParameterSpec;
10import javax.crypto.spec.SecretKeySpec;
11
12public class prog{
13    public static void main(String args[]){
14
15        if (args[0].equals("-genKey")){
16            String keyFileName=args[1];
17            createKey(keyFileName);
18        }
19        else if (args[0].equals("-enc" )||args[0].equals("-dec")){
20
21            try {
22                Cipher c = Cipher.getInstance("AES/CTR/NoPadding");
23                SecretKey secretKey =readKey(args[1]);
24
25                if(args[0].equals("-enc")){
26
27
28                    //generates a random IV
29                    byte[] bytesForIV=new byte[16];
30                    SecureRandom sr = new SecureRandom();
31                    sr.nextBytes(bytesForIV);
32                    IvParameterSpec iv = new IvParameterSpec(bytesForIV);
33
34
35                    //runs cipher
36                    c.init(Cipher.ENCRYPT_MODE, secretKey, iv);
37                    runChiper(c, args[2], args[3],1,bytesForIV);
38
39
40                }else if(args[0].equals("-dec")){
41
42                    // reads the first 16 bytes of the file as IV
43                    IvParameterSpec iv =getIv(args[2]);
44
45
46                    //runs cipher
47                    c.init(Cipher.DECRYPT_MODE, secretKey, iv);
48                    runChiper(c, args[2], args[3],2,null);
49
50                }
51
52
53            } catch (NoSuchAlgorithmException e) {
54                e.printStackTrace();
55            } catch (NoSuchPaddingException e) {
56                e.printStackTrace();
57            } catch (InvalidAlgorithmParameterException e) {
58                e.printStackTrace();
59            } catch (InvalidKeyException e) {
60                e.printStackTrace();
61            } catch (FileNotFoundException e) {
62                System.out.println("File does not exist");
63            }
64
65        }
66        else{
67            System.out.println("Invalid operation");
68        }
69
70
71    }
72    static private IvParameterSpec getIv(String inFile){
73
74        try {
75
76            //reads the first 16 bytes of the file (IV)
77            FileInputStream inputFile = new FileInputStream(inFile);
78            byte[] inputBuf = new byte[16];
79            inputFile.read(inputBuf);
80            return new IvParameterSpec(inputBuf);
81
82        } catch (IOException e) {
83            e.printStackTrace();
84        }
85        return null;
86    }
87
88    static private void runChiper(Cipher c,String inFile,String outFile, int mode, byte[] bytesForIV) throws FileNotFoundException {
89        try{
90            FileOutputStream outputFile = new FileOutputStream(outFile);
91            FileInputStream inputFile = new FileInputStream(inFile);
92            byte[] inputBuf = new byte[1024];
93            int len;
94
95            // IV handling
96            if(mode==1){
97                //If we are encrypting we write the the IV as the first 16 bytes of the file
98                outputFile.write(bytesForIV);
99
100            }
101            if(mode==2){
102                //If we are decrypting we read the first 16 bytes since they are the IV , but we do nothing with it because the cipher is already initialized
103                inputFile.read(new byte[16]);
104            }
105
106            while ((len = inputFile.read(inputBuf)) != -1) {
107                byte[] outputBuf = c.update(inputBuf, 0, len);
108                if ( outputBuf != null ) {
109                    outputFile.write(outputBuf);
110                }
111            }
112
113            byte[] outputBuf = c.doFinal(); //calls for final
114            if ( outputBuf != null ) {
115                outputFile.write(outputBuf);
116            }
117        } catch (IOException e) {
118            e.printStackTrace();
119        } catch (BadPaddingException e) {
120            e.printStackTrace();
121        } catch (IllegalBlockSizeException e) {
122            e.printStackTrace();
123        }
124    }
125
126
127    protected static SecretKeySpec readKey(String keyFileName){
128        // reads a key stored in a file
129        try {
130            byte[] keyBytes = Files.readAllBytes(Paths.get(keyFileName));
131            SecretKeySpec secretKey = new SecretKeySpec(keyBytes, "AES");
132            return secretKey;
133        } catch (IOException e) {
134            e.printStackTrace();
135        }
136        return null;
137    }
138
139    protected static void createKey(String keyFileName){
140        // creates a key and saves it in a file
141        try {
142            KeyGenerator keyGen =  KeyGenerator.getInstance("AES");
143            keyGen.init(128);
144            SecretKey secretKey = keyGen.generateKey();
145
146            File keyFile = new File(keyFileName);
147            FileOutputStream out=null;
148            try  {
149                out = new FileOutputStream(keyFileName);
150                byte[] keyBytes = secretKey.getEncoded();
151                out.write(keyBytes);
152
153            } finally {
154
155                if (out != null) {
156                    out.close();
157                    System.out.println("Key created and saved on file: " +keyFileName);
158                }
159            }
160        } catch (NoSuchAlgorithmException e) {
161            System.out.println("Error creating key");
162        } catch (FileNotFoundException e) {
163            System.out.println("Problem creating file");
164        } catch (IOException e) {
165            e.printStackTrace();
166        }
167
168    }
169}