Write the java program - GenKey

des？我諗我知道你想做咩，應該係encryption/decription既野吧？是做功課吧？

等我略略講一下啦，可能有d bug，我未試過所以唔多清楚架(寫埋個decrypter俾你 in case你要用到)

首先寫個encryptoer class

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 (javax.crypto.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 (javax.crypto.BadPaddingException e) {
} catch (IllegalBlockSizeException e) {
} catch (UnsupportedEncodingException 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 (javax.crypto.BadPaddingException e) {
} catch (IllegalBlockSizeException e) {
} catch (UnsupportedEncodingException e) {
} catch (java.io.IOException e) {
}
return null;
}
}

跟住寫埋你想要既GenKey

import java.io.*;

public class GenKey {
public static void main(String[] args) {
if (args.length == 2) {
String input = args[0];
String path = args[1];
while (input.length() < 8) input = input + ' ';
if (input.length() > 8) input = input.substring(0, 8);
try {
SecretKey key = KeyGenerator.getInstance("DES").generateKey();
DesEncrypter encrypter = new DesEncrypter(key);
String encrypted = encrypter.encrypt(input);
try {
FileInputStream fstream = new
FileInputStream(path);

DataInputStream in =
new DataInputStream(fstream);

while (in.available() !=0)
{
System.out.println (encrypted);
}

in.close();
}
catch (Exception e)
{
}
} catch (Exception e) {
}
}
}
}

2007-04-09 07:36:13 補充：
有d符號響yahoo knowledge display唔到出黎，sorry，請自己理解一下