jdk RSA算法类使用

package com.security.rsa;

import java.security.Key;
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 sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class RSACoder {

public static PublicKey getPublicKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey publicKey = keyFactory.generatePublic(keySpec);
return publicKey;
}

public static PrivateKey getPrivateKey(String key) throws Exception {
byte[] keyBytes;
keyBytes = (new BASE64Decoder()).decodeBuffer(key);
PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
return privateKey;
}

/**
* 得到密钥字符串（经过base64编码）
* @return
*/
public static String getKeyString(Key key) throws Exception {
byte[] keyBytes = key.getEncoded();
String s = (new BASE64Encoder()).encode(keyBytes);
return s;
}

public static void main(String[] args) throws Exception {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
//密钥位数
keyPairGen.initialize(1024);
//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:\n" + publicKeyString);
String privateKeyString = getKeyString(privateKey);
System.out.println("private:\n" + privateKeyString);
//加解密类
Cipher cipher = Cipher.getInstance("RSA");//Cipher.getInstance("RSA/ECB/PKCS1Padding");
//明文
byte[] plainText = "91686280721609".getBytes();
//加密
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] enBytes = cipher.doFinal(plainText);
String s1 = new String(enBytes);
System.out.println("加密后的密文：" + s1);
//通过密钥字符串得到密钥
publicKey = getPublicKey(publicKeyString);
privateKey = getPrivateKey(privateKeyString);
//解密
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[]deBytes = cipher.doFinal(enBytes);
publicKeyString = getKeyString(publicKey);
System.out.println("public:\n" +publicKeyString);
privateKeyString = getKeyString(privateKey);
System.out.println("private:\n" + privateKeyString);
String s = new String(deBytes);
System.out.println(s);
}

}