import java.io.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
/**
 * RSA非對稱型加密的公鑰和私鑰
 */
public class KeyRSA {
 private KeyPairGenerator kpg = null;
 private KeyPair kp = null;
 private PublicKey public_key = null;
 private PrivateKey private_key = null;
 private FileOutputStream public_file_out = null;
 private ObjectOutputStream public_object_out = null;
 private FileOutputStream private_file_out = null;
 private ObjectOutputStream private_object_out = null;
 /**
  * 構造函數(shù)
  * @param in 指定密匙長度（取值范圍：512～2048）
  * @throws NoSuchAlgorithmException 異常
  */
 public KeyRSA(int in, String address) throws NoSuchAlgorithmException,
   FileNotFoundException, IOException {
  kpg = KeyPairGenerator.getInstance("RSA"); //創(chuàng)建‘密匙對'生成器
  kpg.initialize(in); //指定密匙長度（取值范圍：512～2048）
  kp = kpg.genKeyPair(); //生成‘密匙對'，其中包含著一個公匙和一個私匙的信息
  public_key = kp.getPublic(); //獲得公匙
  private_key = kp.getPrivate(); //獲得私匙
  //保存公匙
  public_file_out = new FileOutputStream(address + "/public_key.dat");
  public_object_out = new ObjectOutputStream(public_file_out);
  public_object_out.writeObject(public_key);
  //保存私匙
  private_file_out = new FileOutputStream(address + "/private_key.dat");
  private_object_out = new ObjectOutputStream(private_file_out);
  private_object_out.writeObject(private_key);
 }
 public static void main(String[] args) {
  try {
   new KeyRSA(1024, "c:/key_rsa");
  }
  catch (IOException ex) {
  }
  catch (NoSuchAlgorithmException ex) {
  }
 }
}