file encryption

I would use the javax.crypto package.

Here's an example I yanked from the 'net a while ago, it might help you get started.

import javax.crypto.*;

public class DesEncrypter

{

Cipher ecipher;

Cipher dcipher;

DesEncrypter(SecretKey key)

{

try

{

ecipher = Cipher.getInstance("DES");

dcipher = Cipher.getInstance("DES");

ecipher.init(Cipher.ENCRYPT_MODE, key);

dcipher.init(Cipher.DECRYPT_MODE, key);

}

catch (NoSuchPaddingException e)

{

}

catch (java.security.NoSuchAlgorithmException e)

{

}

catch (java.security.InvalidKeyException e)

{

}

}

public String encrypt(String str)

{

try

{

// Encode the string into bytes using utf-8

byte[] utf8 = str.getBytes("UTF8");

// Encrypt

byte[] enc = ecipher.doFinal(utf8);

// Encode bytes to base64 to get a string

return new sun.misc.BASE64Encoder().encode(enc);

}

catch (BadPaddingException e)

{

}

catch (IllegalBlockSizeException e)

{

}

catch (java.io.IOException e)

{

}

return null;

}

public String decrypt(String str)

{

try

{

// Decode base64 to get bytes

byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

// Decrypt

byte[] utf8 = dcipher.doFinal(dec);

// Decode using utf-8

return new String(utf8, "UTF8");

}

catch (BadPaddingException e)

{

}

catch (IllegalBlockSizeException e)

{

}

catch (java.io.IOException e)

{

}

return null;

}

public static void main(String[] args)

{

try

{

// Generate a temporary key. In practice, you would save this key.

// See also e464 Encrypting with DES Using a Pass Phrase.

SecretKey key = KeyGenerator.getInstance("DES").generateKey();

DesEncrypter encrypter = new DesEncrypter(key);

String encrypted = encrypter.encrypt("Aloha");

String decrypted = encrypter.decrypt(encrypted);

System.out.println(decrypted + "\n" + encrypted + "\n" + decrypted);

}

catch (Exception e)

{

}

}

}

Adeodatusa at 2007-7-8 10:36:18 >