import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
class DesEncrypter {
byte[] buf = new byte[1024];
Cipher ecipher;
Cipher dcipher;
DesEncrypter(SecretKey key) throws Exception{
byte[] iv = new byte[] { (byte) 0x8E, 0x12, 0x39, (byte) 0x9C, 0x07, 0x72, 0x6F, 0x5A };
AlgorithmParameterSpec paramSpec = new IvParameterSpec(iv);
ecipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
dcipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
}
public void encrypt(InputStream in, OutputStream out) throws Exception{
out = new CipherOutputStream(out, ecipher);
int numRead = 0;
while ((numRead = in.read(buf)) >= 0) {
out.write(buf, 0, numRead);
}
out.close();
}
public void decrypt(InputStream in, OutputStream out) throws Exception{
in = new CipherInputStream(in, dcipher);
int numRead = 0;
while ((numRead = in.read(buf)) >= 0) {
out.write(buf, 0, numRead);
}
out.close();
}
}
public class Main {
public static void main(String[] argv) throws Exception {
SecretKey key = KeyGenerator.getInstance("DES").generateKey();
DesEncrypter encrypter = new DesEncrypter(key);
encrypter.encrypt(new FileInputStream("cleartext1"), new FileOutputStream("ciphertext"));
encrypter.decrypt(new FileInputStream("ciphertext"), new FileOutputStream("cleartext2"));
}
}