AES encrypt and decrypt not the same

Question

I use aes to encrypt and decrypt a file. Why is the resulting file not the same as the input?
package mybeans;
import java.io.*;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Hashtable;
import javax.crypto.*;
import javax.crypto.spec.*;
public class Encrypt {
     public static void main(String args[]) throws Exception {
          Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
          SecretKeySpec keySpec = new SecretKeySpec(
                    "05468345670abcde".getBytes(), "AES");
          IvParameterSpec ivSpec = new IvParameterSpec("f45gt7g83sd56210"
                    .getBytes());
          cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
          FileInputStream fis = new FileInputStream(new File("C:\\text.txt"));
          CipherInputStream cis = new CipherInputStream(fis, cipher);
          FileOutputStream fos = new FileOutputStream(new File(
                    "C:\\encrypted.txt"));
          byte[] b = new byte[8];
          int i;
          while ((i = cis.read(b)) != -1) {
               fos.write(b, 0, i);
          fos.flush();
          fos.close();
package mybeans;
import java.io.*;
import javax.crypto.*;
import javax.crypto.spec.*;
public class Decrypt {
     public static void main(String args[]) throws Exception {
          Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
          SecretKeySpec keySpec = new SecretKeySpec(
                    "05468345670abcde".getBytes(), "AES");
          IvParameterSpec ivSpec = new IvParameterSpec("f45gt7g83sd56210"
                    .getBytes());
          cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
          FileInputStream fis = new FileInputStream(new File("C:\\encrypted.txt"));
          CipherInputStream cis = new CipherInputStream(fis, cipher);
          FileOutputStream fos = new FileOutputStream(new File(
                    "C:\\decrypted.txt"));
          byte[] b = new byte[8];
          int i;
          while ((i = cis.read(b)) != -1) {
               fos.write(b, 0, i);
          fos.flush();
          fos.close();
          cis.close();
          fis.close();
}Here is the data in the file:
James,"smith",007
mike,"smith",001
the result is this:
James,"smith",007
mike,"smith",
Edited by: iketurna on Jun 3, 2008 1:47 PM

Answer 1

Thanks sabre!
Very insightful.
I used PKCS5Padding and the file has all of the data, but there are extra padding at the end of the second line
Also,
how would you store your key and iv?
Currently I using this to create the iv and key:
public class KeyClass {
private SecretKeySpec keygeneration() {
SecretKeySpec skeySpec=null;
try {
  KeyGenerator kgen = KeyGenerator.getInstance("AES");
  kgen.init(128);
  SecretKey skey = kgen.generateKey();
  byte[] key = skey.getEncoded();
  skeySpec = new SecretKeySpec(key,"AES");
}catch(Exception e) {
  System.out.println("error in keygen = "+e);
return skeySpec;
public void keyFile() {
try{
FileOutputStream fos=new FileOutputStream("c:\\keyFile.txt");
DataOutputStream dos=new DataOutputStream(fos);
SecretKeySpec skeySpec=keygeneration();
byte[] key=skeySpec.getEncoded();
BASE64Encoder base64 = new BASE64Encoder();
String encodedString = base64.encodeBuffer(key);
dos.write(encodedString.getBytes());
}catch(Exception e1){
  System.out.println("error file write "+e1);
public static void main(String args[]){
  KeyClass cKey = new KeyClass();
  cKey.keyFile();
}Edited by: iketurna on Jun 5, 2008 7:29 AM