非对称加密

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;
publicclass test1 {
 //公钥加密
 publicbyte[] 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
 publicbyte[] 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
 publicbyte[] 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
 publicbyte[] 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);
 }
 publicstaticvoid 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)));
 }
}