RSAUtil.java类

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import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.ShortBufferException;

/**
* RSAUtil工具类
*/
public class RSAUtil {

//RSA key位数
private static final int KEY_SIZE = 512;

//单次RSA加密操作所允许的最大块长度，该值与 KEY_SIZE、padding方法有关。
//1024key->128,2048key->1256,512key->53,11个字节用于保存padding信息。
private static final int BLOCK_SIZE = 53;

private static final int OUTPUT_BLOCK_SIZE = 64;

//private static final int KEY_SIZE = 1024;
//private static final int BLOCK_SIZE = 117;
//private static final int OUTPUT_BLOCK_SIZE = 128;

//private static final int KEY_SIZE = 2048;
//private static final int BLOCK_SIZE = 245;
//private static final int OUTPUT_BLOCK_SIZE = 256;

private static SecureRandom secrand = new SecureRandom();
public static Cipher rsaCipher;

public static String Algorithm="RSA";//RSA、RSA/ECB/PKCS1Padding
//public static String Algorithm="RSA/ECB/PKCS1Padding";//RSA、RSA/ECB/PKCS1Padding

public RSAUtil()throws Exception{

}

/**
* 生成密钥对
* @return KeyPair
* @throws Exception
* @throws NoSuchAlgorithmException
* @throws Exception
*/

public static String[] generateRSAKeyPair(){
  String[] keypair=new String[2];
  try {
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(Algorithm);
            //密钥位数
            keyPairGen.initialize(KEY_SIZE);
            //密钥对
            KeyPair keyPair = keyPairGen.generateKeyPair();

            // 公钥
            PublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

            // 私钥
            PrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

            String publicKeyString = getKeyString(publicKey);
            System.out.println("Public KEY===>" + publicKeyString);
            keypair[0]=publicKeyString;

            String privateKeyString = getKeyString(privateKey);
            System.out.println("Private KEY===>" + privateKeyString);
            keypair[1]=privateKeyString;

        }catch(Exception e){
            System.err.println("Exception:"+e.getMessage());
        }
        return keypair;
}

      public static PublicKey getPublicKey(String key) throws Exception {
            byte[] keyBytes;
            keyBytes = Base64Encoder.decode(key);

            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance(Algorithm);
            PublicKey publicKey = keyFactory.generatePublic(keySpec);
            return publicKey;
      }

      public static PrivateKey getPrivateKey(String key) throws Exception {
            byte[] keyBytes;
            keyBytes =Base64Encoder.decode(key);

            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance(Algorithm);
            PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
            return privateKey;
      }


      public static String getKeyString(Key key) throws Exception {
            byte[] keyBytes = key.getEncoded();
            String s =Base64Encoder.encode(keyBytes);
            return s;
      }

/**
   * 对content采用RSA加密，再BASE64加密
   *
   * @param strPubKey 公钥值
   * @param content 明文串
   * @return cardSecretPwd
   * @throws Exception
   */
  public static String encodeSecret(String publicKeyString, String content) throws Exception {

  try {
   rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
  } catch (NoSuchAlgorithmException e) {
   e.printStackTrace();
  } catch (NoSuchPaddingException e) {
   e.printStackTrace();
   throw e;
  }

  Key publicKey = getPublicKey(publicKeyString);
  try {
   //PublicKey pubkey = keys.getPublic();
   rsaCipher.init(Cipher.ENCRYPT_MODE, publicKey,secrand);
   //System.out.println(rsaCipher.getBlockSize());
   //System.out.println(Message.getBytes("utf-8").length);
   //byte[] encryptedData = rsaCipher.doFinal(Message.getBytes("utf-8"));
   byte[] data = content.getBytes("utf-8");
   int blocks = data.length / BLOCK_SIZE ;
   int lastBlockSize = data.length % BLOCK_SIZE ;
   byte [] encryptedData = new byte[ (lastBlockSize == 0 ? blocks : blocks + 1)* OUTPUT_BLOCK_SIZE];
   for (int i=0; i < blocks; i++)
   {
    //int thisBlockSize = ( i + 1 ) * BLOCK_SIZE > data.length ? data.length - i * BLOCK_SIZE : BLOCK_SIZE ;
    rsaCipher.doFinal(data,i * BLOCK_SIZE, BLOCK_SIZE, encryptedData ,i * OUTPUT_BLOCK_SIZE);
   }
   if (lastBlockSize != 0 ){
    rsaCipher.doFinal(data, blocks * BLOCK_SIZE, lastBlockSize,encryptedData ,blocks * OUTPUT_BLOCK_SIZE);
   }

      return Base64Encoder.encode(encryptedData);

  } catch (InvalidKeyException e) {
   e.printStackTrace();
   throw new IOException("InvalidKey") ;
  }catch (ShortBufferException e) {
   e.printStackTrace();
   throw new IOException("ShortBuffer") ;
  }
  catch (UnsupportedEncodingException e) {
   e.printStackTrace();
   throw new IOException("UnsupportedEncoding") ;
  } catch (IllegalBlockSizeException e) {
   e.printStackTrace();
   throw new IOException("IllegalBlockSize") ;
  } catch (BadPaddingException e) {
   e.printStackTrace();
   throw new IOException("BadPadding") ;
  }finally {

  }
  }

  /**
   * BASE64解密，再RSA解密
   *
   * @param strPriKey 私钥值
   * @param content 密文串
   * @return 用私钥解密串
   * @throws Exception
   */
  public static String decodeSecret(String privateKeyString, String content) throws Exception {

  try {
   rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
  } catch (NoSuchAlgorithmException e) {
   e.printStackTrace();
  } catch (NoSuchPaddingException e) {
   e.printStackTrace();
   throw e;
  }

   byte[] decoded=null;
  try {
   decoded = Base64Encoder.decode(content);
  } catch (Exception e1) {
   e1.printStackTrace();
  }
        Key privateKey = getPrivateKey(privateKeyString);
  try {
   rsaCipher.init(Cipher.DECRYPT_MODE, privateKey, secrand);
   int blocks = decoded.length / OUTPUT_BLOCK_SIZE;
   ByteArrayOutputStream decodedStream = new ByteArrayOutputStream(decoded.length);
   for (int i =0 ;i < blocks ; i ++ )
   {
    decodedStream.write (rsaCipher.doFinal(decoded,i * OUTPUT_BLOCK_SIZE, OUTPUT_BLOCK_SIZE));
   }
   return new String(decodedStream.toByteArray(), "UTF-8");
  } catch (InvalidKeyException e) {
   e.printStackTrace();
   throw new IOException("InvalidKey");
  } catch (UnsupportedEncodingException e) {
   e.printStackTrace();
   throw new IOException("UnsupportedEncoding");
  } catch (IllegalBlockSizeException e) {
   e.printStackTrace();
   throw new IOException("IllegalBlockSize");
  } catch (BadPaddingException e) {
   e.printStackTrace();
   throw new IOException("BadPadding");
  } finally {

  }
  }

  /**
   * BASE64解密，再RSA解密
   *
   * @param strPriKey 私钥值
   * @param content 密文串
   * @return 用私钥解密串
   * @throws Exception
   */
  public static String decodeSecretByPubKey(String publicKeyString, String content) throws Exception {

  try {
   rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
  } catch (NoSuchAlgorithmException e) {
   e.printStackTrace();
  } catch (NoSuchPaddingException e) {
   e.printStackTrace();
   throw e;
  }

   byte[] decoded=null;
  try {
   decoded = Base64Encoder.decode(content);
  } catch (Exception e1) {
   e1.printStackTrace();
  }
        Key publicKey = getPublicKey(publicKeyString);
  try {
   rsaCipher.init(Cipher.DECRYPT_MODE, publicKey, secrand);
   int blocks = decoded.length / OUTPUT_BLOCK_SIZE;
   ByteArrayOutputStream decodedStream = new ByteArrayOutputStream(decoded.length);
   for (int i =0 ;i < blocks ; i ++ )
   {
    decodedStream.write (rsaCipher.doFinal(decoded,i * OUTPUT_BLOCK_SIZE, OUTPUT_BLOCK_SIZE));
   }
   return new String(decodedStream.toByteArray(), "UTF-8");
  } catch (InvalidKeyException e) {
   e.printStackTrace();
   throw new IOException("InvalidKey");
  } catch (UnsupportedEncodingException e) {
   e.printStackTrace();
   throw new IOException("UnsupportedEncoding");
  } catch (IllegalBlockSizeException e) {
   e.printStackTrace();
   throw new IOException("IllegalBlockSize");
  } catch (BadPaddingException e) {
   e.printStackTrace();
   throw new IOException("BadPadding");
  } finally {

  }
  }

      public static void main(String[] args) throws Exception {


            //密钥对
            //String[] keys=generateRSAKeyPair();

      String priKey = "MIIBUwIBADANBgkqhkiG9w0BAQEFAASCAT0wggE5AgEAAkEAkvMGkImJkXv2PfF9f1bk7BTsJFSWGz8iO8FwM8dLF4kBCiAqc8d8bg9ruI1fy2tEqK1koccPA1bRv-lbIWpK8wIDAQABAkA1Sosr6aUJLLJtXmGLx6B3eVL2DfLt6KRqlUkyjejOnKRQ7MIoWNL03yJlsK5IzfMB_D0exZQSYvDg4gtj5_VRAiEA2C-LfYSGWPry8R72_nVOl7gX_rVk22XIyABIwmtqxrkCIQCuAzWFgr7FWvuR46ZM5eqR3JFmn5aCKOFym8KLZfFJCwIga59vv_LjtxRnMWaK666Wi61YNLM1HIwVYovRrQgwxfECIDMexDltuIeX-_HW9AMBRFEHgDuqxHeGdPzLX3K-Rw0TAiAZWIcMc7RsHPrp3nCrPkzDR1ZJwYiE6jBsv737_ZDmFw";
      String pubKey = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAJLzBpCJiZF79j3xfX9W5OwU7CRUlhs_IjvBcDPHSxeJAQogKnPHfG4Pa7iNX8trRKitZKHHDwNW0b_pWyFqSvMCAwEAAQ";
      String s = "ExpTime=1226577284468$Pid=100013$Sid=rlpm001";

      //公钥加密
      String d = encodeSecret(pubKey, s);
      System.out.println("公钥加密密文：" + d);

      //私钥解密
      String c = decodeSecret(priKey, d);

      System.out.println("私钥解密明文：" + c);

      //私钥加密
      String e = encodeSecretByPriKey(priKey, s);
      System.out.println("私钥加密密文：" + e);

      //公钥解密
      String f = decodeSecretByPubKey(pubKey, e);

      System.out.println("公钥解密明文：" + f);
      }

}