0f6Cf1Gh

1protected void EncryptAndroid()
2{
3    byte[] data = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
4            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
5            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',                
6            };
7    byte[] header = {'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd', 'a', 'b', 'c', 'd',
8            'a', 'b', 'c', 'd',};
9    byte[] updatedHeader = {'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D',
10            'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A', 'B', 'C', 'D'};
11
12    try {
13        SecretKey secret = generateKeyAndroid();
14
15        Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
16        cipher.init(Cipher.ENCRYPT_MODE, secret);
17
18        AlgorithmParameters params = cipher.getParameters();
19        byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
20
21        FileOutputStream os = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
22        CipherOutputStream cos = new CipherOutputStream(os, cipher);
23
24        int offset = 0;
25        cos.write(header, offset, 10);
26        cos.write(data, offset, 40);
27
28        FileOutputStream ivStream = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/iv.dat");
29        if (ivStream != null) {
30            Log.d("Encryption", "Writing iv data to output file");
31            ivStream.write(iv);
32        }
33        ivStream.close();
34        cos.close();
35
36        //Create new instance of cipher
37        cipher = Cipher.getInstance("AES/CTR/NoPadding");
38        cipher.init(Cipher.ENCRYPT_MODE, secret);
39
40        AlgorithmParameters params1 = cipher.getParameters();
41        byte[] iv1 = params1.getParameterSpec(IvParameterSpec.class).getIV();
42
43        //Re open the file to Update the header at starting of the file.
44        FileOutputStream os1 = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
45        CipherOutputStream cos1 = new CipherOutputStream(os1, cipher);
46        cos1.write(updatedHeader, offset, 10);
47        cos1.close();
48
49        FileOutputStream ivStream1 = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/iv1.dat");
50        if (ivStream1 != null) {
51            Log.d("Encryption", "Writing iv data to output file");
52            ivStream1.write(iv1);
53        }
54    }catch (Exception e) {
55        e.printStackTrace();
56    }
57}
58protected void DecryptAndroid() {
59    byte[] hBytes = new byte[10];
60    byte[] dBytes = new byte[100];
61
62    try {
63        Log.d("Decryption", "Reading iv data ");
64        File f1 = new File(sdCard.getAbsolutePath() + "/Notes/iv.dat");
65        byte[] newivtext = new byte[(int) f1.length()];
66        FileInputStream readivStream = new FileInputStream(sdCard.getAbsolutePath() + "/Notes/iv.dat");
67        if (readivStream != null) {
68            readivStream.read(newivtext);
69        }
70
71        File f2 = new File(sdCard.getAbsolutePath() + "/Notes/iv1.dat");
72        byte[] newivtext1 = new byte[(int) f2.length()];
73        FileInputStream readivStream1 = new FileInputStream(sdCard.getAbsolutePath() + "/Notes/iv1.dat");
74        if (readivStream1 != null) {
75            readivStream1.read(newivtext1);
76        }
77
78        // The key can also be obtained from the Android Keystore any time as follows:
79        KeyStore keyStore = KeyStore.getInstance("AndroidKeyStore");
80        keyStore.load(null);
81        SecretKey dsecret = (SecretKey) keyStore.getKey("key2", null);
82
83        // Initialize dcipher
84        Cipher dcipher = Cipher.getInstance("AES/CTR/NoPadding");
85        dcipher.init(Cipher.DECRYPT_MODE, dsecret,new IvParameterSpec(newivtext1));
86
87        FileInputStream inputStream = new FileInputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
88        FileOutputStream os = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/sample.decrypted");
89
90        //decrypt header
91        int b = inputStream.read(hBytes);
92        byte[] dB = new byte[10];
93        dB = dcipher.doFinal(hBytes);
94        os.write(dB, 0, b);
95
96        // Re-Initialize dcipher
97        dcipher = Cipher.getInstance("AES/CTR/NoPadding");
98        dcipher.init(Cipher.DECRYPT_MODE, dsecret,new IvParameterSpec(newivtext));
99        FileInputStream inputStream1 = new FileInputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
100        inputStream1.skip(10);
101        CipherInputStream cis = new CipherInputStream(inputStream1, dcipher);
102        b = cis.read(dBytes);
103        while (b != -1) {
104            Log.d("Decryption", "Bytes decrypted" + b);
105            os.write(dBytes, 0, b);
106        }
107        cis.close();
108        os.close();
109
110    } catch (Exception e) {
111        e.printStackTrace();
112    }
113}