• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

Encrypting Strings

 
Greenhorn
Posts: 18
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Hi,
I am using the class below called TripleDesEncryption to encrypt a string. I have got this code of someone else and not sure how i works. I need to somehow generate a key (private I think) to encrypt my string. How do I do this - can the key be a file with any content, or do I have to use the Keygenerator class to produce this key, in the form of a byte array?
Below is my code - also, where do I put this key once I have created it?
Sorry for this basic security question, but it is the first time I am using this kind of stuff.
Thanks for your help in advance.
package com.db.websso.util;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.BadPaddingException;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.IvParameterSpec;
import java.security.InvalidKeyException;
import java.security.GeneralSecurityException;
import sirrus.util.crypt.SecurityProviderLoader;
public class TripleDESEncryption {
private static final String TRIPLE_DES = "DESede";
private static final int TRIPLE_DES_SIZE = 24;
private static final int KEY_START = 0;
private static final int IV_SIZE = 8;
static {
SecurityProviderLoader.loadCryptoProviders();
}
public static String encrypt(byte[] key, String string) {
if(key == null || string == null) return null;
Cipher cipher = getCipher(Cipher.ENCRYPT_MODE, key);
byte[] ciphertext = new byte[0];
try {
ciphertext = cipher.doFinal(string.getBytes());
} catch (Exception e) {
e.printStackTrace();
return null;
}
return Base64.encode(ciphertext);
}
public static String decrypt(byte[] key, String string) {
if(string == null || key == null) return null;
byte[] input = Base64.decode(string);
if(input == null) return null;
Cipher cipher = getCipher(Cipher.DECRYPT_MODE, key);
byte[] plaintext = null;
try {
plaintext = cipher.doFinal(input);
} catch (Exception e) {
e.printStackTrace();
return null;
}
return new String(plaintext);
}

/***********************/
private static Cipher getCipher( int mode, byte[] key )
{
// Retrieve the key parts from the key record
byte [] keybytes = getKeyBytes( key );
byte [] ivbytes = getIvBytes( key );
try
{
Cipher cipher = Cipher.getInstance( TRIPLE_DES +
"/CBC/PKCS5Padding",
"JsafeJCE");
SecretKeySpec keySpec = new SecretKeySpec( keybytes, TRIPLE_DES );
IvParameterSpec ivSpec = new IvParameterSpec( ivbytes );
cipher.init( mode, keySpec, ivSpec );
return cipher;
}
catch( InvalidKeyException ike )
{
throw new RuntimeException( "Key was invalid: " + ike.toString() );
}
catch( GeneralSecurityException catchall )
{
throw new RuntimeException( catchall.toString() );
}
}
private static byte[] getKeyBytes( byte[] key )
{
byte[] keybytes;
keybytes = new byte[ TRIPLE_DES_SIZE ];
System.arraycopy( key, KEY_START, keybytes, 0, TRIPLE_DES_SIZE );
return keybytes;
}
private static byte[] getIvBytes( byte[] key )
{
byte[] ivbytes = new byte[ IV_SIZE ];
System.arraycopy( key, KEY_START + TRIPLE_DES_SIZE, ivbytes, 0,
IV_SIZE );
return ivbytes;
}
}
 
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.
reply
    Bookmark Topic Watch Topic
  • New Topic