Solved

Java crypto

Posted on 2011-02-13
8
361 Views
Last Modified: 2012-05-11
String hashPassword = md5(arg4);

byte[] hPassword = AES.getAESKey(hashPassword, "888");
response = AES.encrypt(hPassword, "challenge");

//---------------------------------------------------------------------------------------

String driverHash = hashPassword;

byte[] driver_hash = AES.getAESKey(driverHash, "888");
String checkResponse = AES.decrypt(driver_hash, "challenge");

I compiled the codes. no error. Tried running the codes, I got a java.lang.NumberFormatException: For input string: "ch"

When I changed "challenge" to a single digit "1", it can run fine. Im stuck. What can be the problem??
0
Comment
Question by:moombaz
  • 4
  • 4
8 Comments
 
LVL 47

Expert Comment

by:for_yan
ID: 34883763
Sorry, I was trying to find this method getAESKey in Java Crypto API, and
somehow, I could not. What is the type of this AES in your code, or
is it a static method. But could not find class AES in Java Crypto either.

Most obvious general point is that it expects String which should be possible to be evaluated
as integer (so "1" will work and "challenge" would not, did you try some other number?),
 but this is certainly not too helpful.

Perhaps someone with experience in Crypto would advise.

Still if you elaborate a little bit on the context, maybe it will help.
0
 
LVL 1

Author Comment

by:moombaz
ID: 34884896
hi for_yan,

im using all of this

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;
import cryptosystem.*;
import java.security.*;
0
 
LVL 47

Expert Comment

by:for_yan
ID: 34884914
So is AES a class within these packages or it is an instance
of some class? If the latter, then what is the class name?
I was looking for a method getAESKey in Java crypto
but it for some reason escapes me.
0
Free Tool: SSL Checker

Scans your site and returns information about your SSL implementation and certificate. Helpful for debugging and validating your SSL configuration.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

 
LVL 47

Expert Comment

by:for_yan
ID: 34884944

Do you have a link to the API documentation for these classes?
Those which I see for Java crypto don't seem to contain this stuff.
Is getAESKey method something which is part of your program, not some method from API?
0
 
LVL 1

Author Comment

by:moombaz
ID: 34885037
No I just call it directly. Im not calling from another class or method
0
 
LVL 1

Author Comment

by:moombaz
ID: 34885043
ouh.. my bad.. it is from this class.

package cryptosystem;

import java.security.MessageDigest;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.KeyGenerator;

import java.security.NoSuchAlgorithmException;

public class AES {
	
	public static String asHex (byte buf[]){
		StringBuffer strbuf = new StringBuffer(buf.length*2);
		int i;
		
		for(i=0; i<buf.length;i++){
			if(((int) buf[i] & 0xff) < 0x10)
				strbuf.append("0");
			
			strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
		}
		return strbuf.toString();
	}
	
	public static byte[] asByte (String hex){
		byte[] bts = new byte[hex.length()/2];
		for(int i=0;i<bts.length;i++){
			bts[i] = (byte) Integer.parseInt(hex.substring(2*i, 2*i+2), 16);
		}
		
		return bts;
	}
	
	/* returns a 128 bit key */
	public static byte[] getAESKey(String password, String salt) 
													throws Exception{
		int IC = 2;
		byte[] keyBytes = null;
		
		MessageDigest md = MessageDigest.getInstance("MD5");
		md.update(password.getBytes("CP1252"));
		md.update(salt.getBytes("CP1252"));
		for(int i=1; i<IC; i++){
			md.update(md.digest());
		}
		
		keyBytes = md.digest();
		
		return keyBytes;
	}
	
	public static byte[] generateKey(){
		byte[] raw = null;
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128);
			
			SecretKey skey = kgen.generateKey();
			raw = skey.getEncoded();
			
		}catch (NoSuchAlgorithmException e){
			System.out.println(e);
		}
		
		return raw;
	}
	
	public static String encrypt(byte[] key, String plainText) 
													throws Exception{
		byte[] encrypted = null;
		
		SecretKeySpec sKeySpec = new SecretKeySpec(key, "AES");
		Cipher cipher = Cipher.getInstance("AES");
		
		cipher.init(Cipher.ENCRYPT_MODE, sKeySpec);
		
		encrypted = cipher.doFinal(plainText.getBytes());
		
		return asHex(encrypted);
	}
	
	public static String decrypt(byte[] key, String cipherText) 
													throws Exception{
		byte[] decrypted = null;
		
		SecretKeySpec sKeySpec = new SecretKeySpec(key, "AES");
		Cipher cipher = Cipher.getInstance("AES");
		
		cipher.init(Cipher.DECRYPT_MODE, sKeySpec);
		
		decrypted = cipher.doFinal(asByte(cipherText));
		
		return new String(decrypted);
	}
	
	public static void main(String[] args) throws Exception {
		String message="This is just an example";
		String password = "apple1";
		String salt = "47BCE5C74F589F4867DBD57E9CA9F808";
		
		// Create a key
		byte[] key = getAESKey(password, salt);
		
		String hex = asHex(key);
		System.out.println("hex: "+hex+" Len:"+hex.getBytes().length);
		
		String hash = "48c27a623063a286358e0bf65bd5afbd";
		byte[] hashBytes = asByte(hash);
		
		boolean expected = java.util.Arrays.equals(hashBytes, key);
		System.out.println("Test " + (expected ? "SUCCEEDED!" : "FAILED!"));
		
		String encrypted = encrypt(key, message);
		System.out.println("encrypted: "+encrypted);
		
		String original = decrypt(hashBytes, encrypted);
		System.out.println("original: "+original);
	}
}

Open in new window

0
 
LVL 47

Accepted Solution

by:
for_yan earned 500 total points
ID: 34885185
Is "challenge" - is something that you yourself specify?
As you understand I'm no specialist in this stuff, but looking at this code
it seems to me that it expects in this place the string which has only Hex number,
which means this string is a key which should be made up of digits and letters "a" through "f",
that's why "challenge"  which contains "h" and "l" and "g" causes problems.
If this is something you select yourself - try to select the key following this rule,
say 3a4b2345e should be fine, but 1t34s - is not good as "s" and "t" has no meaning in Hex number.
0
 
LVL 1

Author Comment

by:moombaz
ID: 34885663
I've tried and it doesnt work. "challenge" i replaced to "3a4b2345e". Error message that I got is javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16.

Still doesnt work. anw, i have been encrypting and decrypting using the same key. all of them works except for this one.
0

Featured Post

Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
servlet doXXX methods 3 62
fibonacci ten numbers 4 45
ejb wildfly example 2 23
String array comparison 4 38
For customizing the look of your lightweight component and making it look lucid like it was made of glass. Or: how to make your component more Apple-ish ;) This tip assumes your component to be of rectangular shape and completely opaque. (COD…
Introduction This article is the second of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers the basic installation and configuration of the test automation tools used by…
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
The viewer will learn how to implement Singleton Design Pattern in Java.

860 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question