Java Cryptography Extension giving me different result every time

[sa sam]

i am using Java Cryptography Extension to encrypt/decrypt the password but it is giving me different encrypted string every time even though i am passing same string my sample code is as follows -

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;


public class Main {

public static void main(String arg[]) throws Exception {
for ( int i= 0 ; i < 1; i ++)
{
System.out.println(encrypt("admin"));
}
}

public static String encrypt(String x) throws Exception {
String pass = null ;
try{
KeyGenerator keygenerator = KeyGenerator.getInstance("AES");
keygenerator.init(128);
SecretKey myDesKey = keygenerator.generateKey();
Cipher desCipher;
desCipher = Cipher.getInstance("AES");
desCipher.init(Cipher.ENCRYPT_MODE, myDesKey);
byte[] text = x.getBytes();
byte[] textEncrypted = desCipher.doFinal(text);
pass = textEncrypted.toString();
}catch(Exception e){
e.printStackTrace();
}
return pass;
}
}

[Jesper de Jong]

Please UseCodeTags when you post source code.

[Jesper de Jong]

You get a different result each time because you are generating a new, random encryption key every time.

You should generate the key only once, and then store it and re-use it for encrypting and decrypting.

[sa sam]

Actually, i want to store that value into the database,
i will be very thankful if you gave me the example.
(just want to develop login page)

[David Newton]

You're asking how to store a value into a database?

[sa sam]

i am not asking how to store value. i am asking about, how to get constant encryption value.

[David Newton]

Jesper Young wrote:You should generate the key only once, and then store it and re-use it for encrypting and decrypting.

[Garrett Rowe]

Actually you should never need to decrypt the password. All you need is a one way hash, you can then store the hashed password in the database. When the user goes to login, you just hash the password that the user enters by the same method and check whether the two hashes are the same. You should also salt the password with a random salt to help prevent multiple accounts from being compromised using a rainbow table should your database become compromised. The salt can be stored in the database along with the hashed password. All this can easily be done using java.security.MessageDigest, and java.security.SecureRandom.

public int createRandomSalt() {
   SecureRandom rnd = new SecureRandom();
   //..
}
public String encrypt(String password, int salt) {
  MessageDigest msgDigest = MessageDigest.getInstance("SHA-256"); //Or MD5 or whatever algorithm you want to use
  //...
}

[Jesper de Jong]

ajay chavan wrote:i am not asking how to store value. i am asking about, how to get constant encryption value.

What your code above does, is like this: Every time you go out of your house and lock the door, you put a completely new lock with a new key on the door. And your questions is like: "Why does the key look different every time after I locked my door?". Answer: Because you're putting a new lock on the door every time...

[Henry Wong]

Jesper Young wrote:

ajay chavan wrote:i am not asking how to store value. i am asking about, how to get constant encryption value.

What your code above does, is like this: Every time you go out of your house and lock the door, you put a completely new lock with a new key on the door. And your questions is like: "Why does the key look different every time after I locked my door?". Answer: Because you're putting a new lock on the door every time...

Also, the key is not saved by the encrypt() method... so it more like "every time you go out of your house and lock the door, you put a completely new lock with a new key on the door. And throw away the key once you drive off".

Henry

[David Newton]

That's even *more* secure than a one-time pad, it's like a *no*-time pad!

Finally, I can make my mark on sci.crypt!!