package com.bao.examples.security;
import java.io.*;
import java.security.*;
import javax.crypto.*;
/**
* This program tests the RSA cipher. Usage:<br>
* java RSATest -genkey public private<br>
* java RSATest -encrypt plaintext encrypted public<br>
* java RSATest -decrypt encrypted decrypted private<br>
* @author Cay Horstmann
* @version 1.0 2004-09-14
*/
public class RSATest
{
public static void main(String[] args)
{
if(args == null || args.length == 0)
{
System.out.println(usage());
System.exit(1);
}
try
{
if (args[0].equals("-genkey"))
{
KeyPairGenerator pairgen = KeyPairGenerator.getInstance("RSA");
SecureRandom random = new SecureRandom();
pairgen.initialize(KEYSIZE, random);
KeyPair keyPair = pairgen.generateKeyPair();
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(args[1]));
out.writeObject(keyPair.getPublic());
out.close();
out = new ObjectOutputStream(new FileOutputStream(args[2]));
out.writeObject(keyPair.getPrivate());
out.close();
}
else if (args[0].equals("-encrypt"))
{
KeyGenerator keygen = KeyGenerator.getInstance("AES");
SecureRandom random = new SecureRandom();
keygen.init(random);
SecretKey key = keygen.generateKey();
// wrap with RSA public key
ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(args[3]));
Key publicKey = (Key) keyIn.readObject();
keyIn.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.WRAP_MODE, publicKey);
byte[] wrappedKey = cipher.wrap(key);
DataOutputStream out = new DataOutputStream(new FileOutputStream(args[2]));
out.writeInt(wrappedKey.length);
out.write(wrappedKey);
InputStream in = new FileInputStream(args[1]);
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, key);
crypt(in, out, cipher);
in.close();
out.close();
}
else if (args[0].equals("-decrypt"))
{
DataInputStream in = new DataInputStream(new FileInputStream(args[1]));
int length = in.readInt();
byte[] wrappedKey = new byte[length];
in.read(wrappedKey, 0, length);
// unwrap with RSA private key
ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(args[3]));
Key privateKey = (Key) keyIn.readObject();
keyIn.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.UNWRAP_MODE, privateKey);
Key key = cipher.unwrap(wrappedKey, "AES", Cipher.SECRET_KEY);
OutputStream out = new FileOutputStream(args[2]);
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, key);
crypt(in, out, cipher);
in.close();
out.close();
}
else
{
System.out.println(usage());
System.exit(1);
}
}
catch (IOException e)
{
e.printStackTrace();
}
catch (GeneralSecurityException e)
{
e.printStackTrace();
}
catch (ClassNotFoundException e)
{
e.printStackTrace();
}
}
/**
* Uses a cipher to transform the bytes in an input stream and sends the transformed bytes to an
* output stream.
* @param in the input stream
* @param out the output stream
* @param cipher the cipher that transforms the bytes
*/
public static void crypt(InputStream in, OutputStream out, Cipher cipher) throws IOException,
GeneralSecurityException
{
int blockSize = cipher.getBlockSize();
int outputSize = cipher.getOutputSize(blockSize);
byte[] inBytes = new byte[blockSize];
byte[] outBytes = new byte[outputSize];
int inLength = 0;
;
boolean more = true;
while (more)
{
inLength = in.read(inBytes);
if (inLength == blockSize)
{
int outLength = cipher.update(inBytes, 0, blockSize, outBytes);
out.write(outBytes, 0, outLength);
}
else more = false;
}
if (inLength > 0) outBytes = cipher.doFinal(inBytes, 0, inLength);
else outBytes = cipher.doFinal();
out.write(outBytes);
}
private static final int KEYSIZE = 512;
private static String usage()
{
return "java RSATest -genkey public.key private.key\n"
+ "java RSATest -encrypt plaintextFile encryptedFile public.key\n"
+ "java RSATest -decrypt encryptedFile decryptedFile private.key\n";
}
}