ehripUsp

1byte[] 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'};
2byte[] header = {'a','b','c','d','a','b','c','d','a','b','c','d','a','b','c','d'};
3byte[] updatedHeader = {'A','B','C','D','A','B','C','D','A','B','C','D','A','B','C','D'};
4
5byte[] dBytes = new byte[400];
6int offset =0;
7
8SecretKey secretKey = generateKey();
9
10try {
11    //cipher initialization for Encryption
12    Cipher cipher = Cipher.getInstance("AES");
13    cipher.init(Cipher.ENCRYPT_MODE,secretKey);
14
15    FileOutputStream os = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
16    CipherOutputStream cos = new CipherOutputStream(os,cipher);
17    FileOutputStream os1 = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
18    CipherOutputStream cos1 = new CipherOutputStream(os1,cipher);
19
20    Log.d("Encryption", "Writing cipher text to output file");
21    cos.write(header, offset, 10); //Write 10 bytes header data with smallCase array
22    cos.write(data, offset, 40); // write 40 bytes actual data
23    cos.close();
24
25    cos1.write(updatedHeader, offset, 10); // Overwrite header data with capitalCase array data
26    cos1.close();
27
28    //Cipher initialization for decryption
29    Cipher dcipher = Cipher.getInstance("AES");
30    dcipher.init(Cipher.DECRYPT_MODE,secretKey);
31
32    FileInputStream inputStream = new FileInputStream(sdCard.getAbsolutePath() + "/Notes/sample.encrypted");
33
34    CipherInputStream cis = new CipherInputStream(inputStream,dcipher);
35    FileOutputStream dos = new FileOutputStream(sdCard.getAbsolutePath() + "/Notes/sample.decrypted");
36
37    int b = cis.read(dBytes);
38    while(b != -1) {
39        Log.d("Decryption","Bytes decrypted" + b);
40        dos.write(dBytes, 0, b);
41        b = cis.read(dBytes);
42    }
43    cis.close();
44    os.close();
45}catch (Exception   e) { e.printStackTrace();  }