RSA加密算法

package com.zzti.fyg.psw.encryption;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import javax.crypto.Cipher;

public class RSAcrypto {
 private final static String RSA = "RSA";
 public static PublicKey uk;
 public static PrivateKey rk;

 public static void generateKey() throws Exception {
  KeyPairGenerator gen = KeyPairGenerator.getInstance(RSA);
  gen.initialize(512, new SecureRandom());
  KeyPair keyPair = gen.generateKeyPair();
  uk = keyPair.getPublic();
  rk = keyPair.getPrivate();
 }

 private static byte[] encrypt(String text, PublicKey pubRSA)
   throws Exception {
  Cipher cipher = Cipher.getInstance(RSA);
  cipher.init(Cipher.ENCRYPT_MODE, pubRSA);
  return cipher.doFinal(text.getBytes());
 }

 public final static String encrypt(String text) {
  try {
   return byte2hex(encrypt(text, uk));
  } catch (Exception e) {
   e.printStackTrace();
  }
  return null;
 }

 public final static String decrypt(String data) {
  try {
   return new String(decrypt(hex2byte(data.getBytes())));
  } catch (Exception e) {
   e.printStackTrace();
  }
  return null;
 }

 private static byte[] decrypt(byte[] src) throws Exception {
  Cipher cipher = Cipher.getInstance(RSA);
  cipher.init(Cipher.DECRYPT_MODE, rk);
  return cipher.doFinal(src);
 }

 public static String byte2hex(byte[] b) {
  String hs = "";
  String stmp = "";
  for (int n = 0; n < b.length; n++) {
   stmp = Integer.toHexString(b[n] & 0xFF);
   if (stmp.length() == 1)
    hs += ("0" + stmp);
   else
    hs += stmp;
  }
  return hs.toUpperCase();
 }

 public static byte[] hex2byte(byte[] b) {
  if ((b.length % 2) != 0)
   throw new IllegalArgumentException("长度不是偶数");
  byte[] b2 = new byte[b.length / 2];
  for (int n = 0; n < b.length; n += 2) {
   String item = new String(b, n, 2);
   b2[n / 2] = (byte) Integer.parseInt(item, 16);
  }
  return b2;
 }

 public static void main(String args[]) {
  try {
   RSAcrypto.generateKey();
   String cipherText = RSAcrypto.encrypt("f二少");
   System.out.println(cipherText);
   String plainText = RSAcrypto.decrypt(cipherText);
   System.out.println(plainText);
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
}