Cipher DoFinal returns 0

Question

Hi
I want to wrtite a program that would take
a)Plain password
b)Encode it
c)Write to a file
Second program
a)to read the file
b)get the encode password and decode it
c)get the plain password back.
First code is as follows:
import java.io.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class EncryptFile
public static void main(String args[]) {
if (args.length < 1)
System.out.println("Usage: java EncryptFile <password>");
System.exit(-1);
try
File desFile = new File("encrypt.des");
if(desFile.exists())
desFile.delete();
FileInputStream fis=null;
FileOutputStream fos;
CipherInputStream cis;
// Creation of Secret key
byte key[] = "abcdEFGH".getBytes();
SecretKeySpec secretKey = new SecretKeySpec(key,"DES");
// Creation of Cipher objects
Cipher encrypt =
Cipher.getInstance("DES/ECB/PKCS5Padding");
encrypt.init(Cipher.ENCRYPT_MODE, secretKey);
// Open the Plaintext file
String password = args[0];
System.out.println(" Plain password " + password );
//Take the plain password + encode it + encrypt it
byte[] utf8 = password.getBytes("UTF8");
// Encrypt
byte[] enc = encrypt.doFinal();
// Encode bytes to base64 to get a string
password=new sun.misc.BASE64Encoder().encode(enc);
System.out.println(" Encode password " + password);
//write it to a file
byte[] encodearr = password.getBytes();
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(desFile));
bos.write(encodearr);
bos.flush();
bos.close();
} catch (Exception e)
e.printStackTrace();
The decrypt code is as follows:
import java.io.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class DecryptFile
public static void main(String args[]) {
try
File desFile = new File("encrypt.des");
File desFileBis = new File("decrypt.des");
FileInputStream fis;
FileOutputStream fos;
CipherInputStream cis;
// Creation of Secret key
byte key[] = "abcdEFGH".getBytes();
SecretKeySpec secretKey = new SecretKeySpec(key,"DES");
// Creation of Cipher objects
Cipher decrypt =
Cipher.getInstance("DES/ECB/PKCS5Padding");
decrypt.init(Cipher.DECRYPT_MODE, secretKey);
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(desFile));
byte b[] = new byte[100];
int i = bis.read(b);
String temp=null;
while (i !=-1)
temp = new String(b,0,i);
System.out.println(" data is " + temp);
i = bis.read(b);
byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(temp);
System.out.println( "dec " + dec.length);
// Decrypt
byte[] utf8 = decrypt.doFinal(dec);
System.out.println( "utf " + utf8.length);
} catch (Exception e)
e.printStackTrace();
First i run the EncryptFile.java the o/p is as follows:
C:\test\Alldump>java EncryptFile india123
Plain password india123
Encode password eYQJ953cHuI=
Now when i run the Decryptfile .java the o/p is as follows:
C:\test\Alldump>java DecryptFile
data is eYQJ953cHuI=
dec 8
utf 0
What can be the problem her
Best Regards
Manoj

Answer 1

I have not studied all your code but one obvious point -
//Take the plain password + encode it + encrypt it
byte[] utf8 = password.getBytes("UTF8");
// Encrypt
byte[] enc = encrypt.doFinal();You have never encrypted anything! Should this not be
//Take the plain password + encode it + encrypt it
byte[] utf8 = password.getBytes("UTF8");
// Encrypt
byte[] enc = encrypt.doFinal(utf8);