java签名证书

 import java.io.FileInputStream;
 import java.security.KeyStore;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.Signature;
 import java.security.cert.Certificate;
 import java.security.cert.CertificateFactory;
 import java.security.cert.X509Certificate;

 import javax.crypto.Cipher;

 public class CertificateCoder {

     public static final String CERT_TYPE="X.509";

     /**
      * 获取私匙
      * @param keyStorePath
      * @param pwd
      * @param alias
      * @return PrivateKey 私匙
      * @throws Exception
      */
     private static PrivateKey getPrivateKey(String keyStorePath,String pwd,String alias) throws Exception{
         KeyStore ks=getKeyStore(keyStorePath, pwd);
         return (PrivateKey)ks.getKey(alias, pwd.toCharArray());

     }

     /**
      *
      * @param keyStorePath
      * @param pwd
      * @return keyStore 密匙库
      * @throws Exception
      */
     private static KeyStore getKeyStore(String keyStorePath,String pwd) throws Exception{
         KeyStore ks=KeyStore.getInstance(KeyStore.getDefaultType());
         FileInputStream in=new FileInputStream(keyStorePath);
         ks.load(in,pwd.toCharArray());
         in.close();
         return ks;
     }

     /**
      *
      * @param certificatePath
      * @return Certificate 证书
      * @throws Exception
      */
     private static Certificate getCertificate(String certificatePath) throws Exception{
         CertificateFactory factory=CertificateFactory.getInstance(CERT_TYPE);
         FileInputStream in=new FileInputStream(certificatePath);
         Certificate certificate=factory.generateCertificate(in);
         in.close();
         return certificate;

     }

     /**
      * 通过证书返回公匙
      * @param certificatePath
      * @return Publickey 返回公匙
      * @throws Exception
      */
     private static PublicKey getPublicKeyByCertificate(String certificatePath) throws Exception{
         Certificate certificate=getCertificate(certificatePath);
         return certificate.getPublicKey();
     }

     /**
      *
      * @param keyStorePath
      * @param alias
      * @param pwd
      * @return Certificate 证书
      * @throws Exception
      */
     private static Certificate getCertificate(String keyStorePath,String alias,String pwd) throws Exception{
         KeyStore ks=getKeyStore(keyStorePath, pwd);
         //获取证书
         return ks.getCertificate(alias);
     }

     /**
      * 私匙加密
      * @param data
      * @param keyStorePath
      * @param alias
      * @param pwd
      * @return byte[] 被私匙加密的数据
      * @throws Exception
      */
     public static byte[] encryptByPrivateKey(byte[] data,String keyStorePath,String alias,String pwd) throws Exception{
         PrivateKey privateKey=getPrivateKey(keyStorePath, pwd, alias);
         //对数据进行加密
         Cipher cipher=Cipher.getInstance(privateKey.getAlgorithm());
         cipher.init(Cipher.ENCRYPT_MODE, privateKey);
         return cipher.doFinal(data);

     }

     /**
      * 私匙解密
      * @param data
      * @param keyStorePath
      * @param alias
      * @param pwd
      * @return byte[] 私匙解密的数据
      * @throws Exception
      */
     public static byte[] decryptByPrivateKey(byte[] data,String keyStorePath,String alias,String pwd) throws Exception{
         PrivateKey privateKey=getPrivateKey(keyStorePath, pwd, alias);
         Cipher cipher=Cipher.getInstance(privateKey.getAlgorithm());
         cipher.init(cipher.DECRYPT_MODE, privateKey);
         return cipher.doFinal(data);
     }

     /**
      * 公匙加密
      * @param data
      * @param cerPath
      * @return byte[] 被公匙加密的数据
      * @throws Exception
      */
     public static byte[] encryptByPublicKey(byte[] data,String cerPath) throws Exception{
         //获取公匙
         PublicKey publicKey=getPublicKeyByCertificate(cerPath);
         System.out.println(publicKey.getAlgorithm());
         Cipher cipher=Cipher.getInstance(publicKey.getAlgorithm());
         cipher.init(Cipher.ENCRYPT_MODE, publicKey);
         return cipher.doFinal(data);
     }

     /**
      * 公匙解密
      * @param data
      * @param cerPath
      * @return
      * @throws Exception
      */
     public static byte[] decryptByPublicKey(byte[] data,String cerPath) throws Exception{
         PublicKey publicKey=getPublicKeyByCertificate(cerPath);
         Cipher cipher=Cipher.getInstance(publicKey.getAlgorithm());
         cipher.init(Cipher.DECRYPT_MODE, publicKey);
         return cipher.doFinal(data);
     }

     /**
      * 签名
      * @param sign
      * @param keyStorePath
      * @param pwd
      * @param alias
      * @return
      * @throws Exception
      */
     public static byte[] sign(byte[] sign,String keyStorePath,String pwd,String alias) throws Exception{
         //获取证书
         X509Certificate x509=(X509Certificate)getCertificate(keyStorePath, alias, pwd);
         //构建签名,由证书指定签名算法
         Signature sa=Signature.getInstance(x509.getSigAlgName());
         //获取私匙
         PrivateKey privateKey=getPrivateKey(keyStorePath, pwd, alias);
         sa.initSign(privateKey);
         sa.update(sign);
         return sa.sign();
     }

     /**
      * 验证签名
      * @param data
      * @param sign
      * @param cerPath
      * @return
      * @throws Exception
      */
     public static boolean verify(byte[] data,byte[] sign,String cerPath) throws Exception{
         X509Certificate x509=(X509Certificate)getCertificate(cerPath);
         Signature sa=Signature.getInstance(x509.getSigAlgName());
         sa.initVerify(x509);
         sa.update(data);
         return sa.verify(sign);
     }
 }