每日一得--非对称加密算法之（RSA）

import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;


public class RSAMain {
private static String str= "husq RSA test";
/**
* @param args
*/
public static void main(String[] args) {
jdkRSA();
}

public static void jdkRSA(){
try{
//1 初始化秘钥
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(512);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
RSAPublicKey rsaPublicKey = (RSAPublicKey)keyPair.getPublic();
RSAPrivateKey rsaPrivateKey = (RSAPrivateKey)keyPair.getPrivate();
System.out.println("public key : "+ Base64.encodeBase64String(rsaPublicKey.getEncoded()));
System.out.println("private key : "+ Base64.encodeBase64String(rsaPrivateKey.getEncoded()));

//2 私钥加密，公钥解密---加密
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
KeyFactory kFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = kFactory.generatePrivate(pkcs8EncodedKeySpec);
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, privateKey);
byte[] result = cipher.doFinal(str.getBytes());
System.out.println("私钥加密，公钥解密---加密 :"+ Base64.encodeBase64String(result));


//3,私钥加密，公钥解密--解密
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
kFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = kFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, publicKey);
result = cipher.doFinal(result);
System.out.println("私钥加密，公钥解密---解密："+ new String(result));

//4,公钥加密，私钥解密--加密
x509EncodedKeySpec  = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
kFactory = KeyFactory.getInstance("RSA");
publicKey = kFactory.generatePublic(x509EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
result = cipher.doFinal(str.getBytes());
System.out.println("公钥加密，私钥解密---加密："+Base64.encodeBase64String(result));

//5,公钥加密，私钥解密--解密
pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
kFactory = KeyFactory.getInstance("RSA");
privateKey = kFactory.generatePrivate(pkcs8EncodedKeySpec);
cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);

cipher.doFinal(result);

System.out.println("公钥加密，私钥解密---解密："+new String(result));

//6,用私钥对信息生成数字签名

Signature signature = Signature.getInstance(“RSA”);  
signature.initSign(privateKey);  
signature.update(result);  
System.out.println("用私钥对信息生成数字签名："+encryptBASE64(signature.sign()));

//7,验证签名是否正常

Signature signature = Signature.getInstance(“RSA”);  
signature.initVerify(pubKey);  
signature.update(result);  
  // 验证签名是否正常  

System.out.println("验证签名是否正常："+ signature.verify(decryptBASE64(sign)));

}catch(Exception e){
e.printStackTrace();
}
}


}