RSA 加解密java实现

非对称加密

 非对称加密有一对密钥，公钥和私钥。可以用公钥加密，也可以用私钥加密。不过，公钥加密必须用私钥解密，私钥加密必须用公钥解密。如果不对应，则会报这样的异常

javax.crypto.BadPaddingException: Data must start with zero

 

代码如下

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import javax.crypto.Cipher;

public class RSA {

    //公钥加密
    public byte[] PublicEncrypt(KeyPair key,String str)throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key.getPublic());
        return cipher.doFinal(str.getBytes("UTF8"));
    }

    //公钥解密
    public byte[] PublicDECRYPT (KeyPair key,byte[]  data)throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, key.getPublic());
        return cipher.doFinal(data);
    }

    //私钥加密
    public byte[] PrivateEncrypt (KeyPair key,String str)throws Exception {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, key.getPrivate());
        return cipher.doFinal(str.getBytes("UTF8"));
    }

    //私钥解密
    public byte[] PrivateDECRYPT(KeyPair key,byte[]  data)throws Exception  {
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, key.getPrivate());
        return cipher.doFinal(data);
    }


    public static void main(String args[]) throws Exception {
        String str = "Hello World!";
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
        keyGen.initialize(1024);
        KeyPair key = keyGen.generateKeyPair();
        test1 t = new test1();
        System.out.println("加密前原文:"+str);
        byte[] data = t.PublicEncrypt(key,str);
        System.out.println("私钥解密后:"+new String(t.PrivateDECRYPT(key,data)));
        byte[] data1 = t.PrivateEncrypt(key,str);
        System.out.println("公钥解密后:"+new String(t.PublicDECRYPT(key,data1)));
    }
}