RSA 加密在编程中很常见，iOS 安卓要用，Java 也要用，最近因为大数据的项目要用到，就写了一份，这里备份一下，也希望能帮到要用的朋友们。
以下是整体代码：
import org.apache.commons.codec.binary.Base64;
import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
/**
* Hello RSA!
*
*/
public class RSAUtils
{
private static Map<Integer,String> keyMap=new HashMap<>();
public static void main( String[] args ) throws Exception {
//生成公钥和私钥
getKeyPair();
//加密字符串
String password="liupengkun";
System.out.println("随机生成的公钥为："+keyMap.get(0));
System.out.println("随机生成的私钥为："+keyMap.get(1));
String passwordEn=encrypt(password,keyMap.get(0));
System.out.println(password+"\t加密后的字符串为："+passwordEn);
String passwordDe=decrypt(passwordEn,keyMap.get(1));
System.out.println("还原后的字符串为："+passwordDe);
}
/**
* 随机生成密钥对
* @throws NoSuchAlgorithmException
*/
public static void getKeyPair() throws Exception {
//KeyPairGenerator类用于生成公钥和密钥对，基于RSA算法生成对象
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
//初始化密钥对生成器，密钥大小为96-1024位
keyPairGen.initialize(1024,new SecureRandom());
//生成一个密钥对，保存在keyPair中
KeyPair keyPair = keyPairGen.generateKeyPair();
PrivateKey privateKey = keyPair.getPrivate();//得到私钥
PublicKey publicKey = keyPair.getPublic();//得到公钥
//得到公钥字符串
String publicKeyString=new String(Base64.encodeBase64(publicKey.getEncoded()));
//得到私钥字符串
String privateKeyString=new String(Base64.encodeBase64(privateKey.getEncoded()));
//将公钥和私钥保存到Map
keyMap.put(0,publicKeyString);//0表示公钥
keyMap.put(1,privateKeyString);//1表示私钥
}
/**
* RSA公钥加密
*
* @param str
* 加密字符串
* @param publicKey
* 公钥
* @return 密文
* @throws Exception
* 加密过程中的异常信息
*/
public static String encrypt(String str,String publicKey) throws Exception {
//base64编码的公钥
byte[] decoded = Base64.decodeBase64(publicKey);
RSAPublicKey pubKey= (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
//RAS加密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE,pubKey);
String outStr=Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
return outStr;
}
/**
* RSA私钥解密
*
* @param str
* 加密字符串
* @param privateKey
* 私钥
* @return 铭文
* @throws Exception
* 解密过程中的异常信息
*/
public static String decrypt(String str,String privateKey) throws Exception {
//Base64解码加密后的字符串
byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
//Base64编码的私钥
byte[] decoded = Base64.decodeBase64(privateKey);
PrivateKey priKey = KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
//RSA解密
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE,priKey);
String outStr=new String(cipher.doFinal(inputByte));
return outStr;
}
}
在程序中，我们首先利用 getKeyPair() 函数生成公钥和私钥并将其保存到 Map 集合中。然后，基于产生的公钥对明文进行加密。针对已经已经加密的密文，我们再次使用私钥解密，得到明文。
上述程序的输出结果为：
随机生成的公钥为：MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCs+QkIaMuogm99lcRjV1xT+AuTHlgIT65svpG8MrPnfjApnkQAdT++VwubdU9ULwVthc6GLuXORxakN/Odd+/jd8WY2IJMVttkYR1mhAZQkx9AU2frNbq97gS9menvL7pQk2ji42Sl1gcZ7tY5+XXGN7EYS52+JGdgfuxGoWNMQwIDAQAB
随机生成的私钥为：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
liupengkun 加密后的字符串为：EUz2Goo0m5mNk0al87dsrcqIuzIzNAEvzTBJOXUOiujubJgqVPmsM880aahLbKrNjl5ArJPtguznJ9PruwSBUnGoPpAMetHp+23RBkXB2DwAA200qejLyKt1PkeTLJjDrQVhohlsF+K48TaGpTSfDMoPli3E6eTdS+dk1Xib4SI=
还原后的字符串为：liupengkun
