java rsa加密(利用模数和公钥指数)

java 利用(利用模数和公钥指数)RSA加密

最近抓包某第二课堂软件发现加密，脱壳后找出了模数和公钥指数，并利用模数和公钥指数加密

利用到的包

import java.math.BigInteger;
import java.security.interfaces.RSAPublicKey;
import java.security.KeyFactory;
import java.security.spec.RSAPublicKeySpec;
import java.security.PublicKey;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.util.Base64;

具体代码

public static final String a = "138128429165014960214288316246915564109957848967973935739058724552651480736930647934382755460619033465620384391387196627089864034424350665139841418169631846827850418205510584071030219835341930960684577738773846628024223162766742868530563861053134130417499539521288428945157726371402147367583657263208271059771";
public static final String b = "65537";


public static void main(String[] args) throws Exception{
	
	RSAPublicKey res = a(a, b);
	//待加密内容
	String text = "我是一个小test";
	//加密后内容
	String en_text = a(res, text);
	
}  
  
public static RSAPublicKey a(String str, String str2) {
    try {
        return (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new RSAPublicKeySpec(new BigInteger(str), new BigInteger(str2)));
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}

public static String a(PublicKey publicKey, String str) throws Exception {
    Cipher instance = Cipher.getInstance("RSA");
    instance.init(1, publicKey);
    byte[] bytes = str.getBytes("UTF-8");
    int length = bytes.length;
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    int i = 0;
    int i2 = 0;
    while (true) {
        int i3 = length - i;
        if (i3 > 0) {
            byte[] doFinal = i3 > 117 ? instance.doFinal(bytes, i, 117) : instance.doFinal(bytes, i, i3);
            byteArrayOutputStream.write(doFinal, 0, doFinal.length);
            i2++;
            i = i2 * 117;
        } else {
            byte[] byteArray = byteArrayOutputStream.toByteArray();
            byteArrayOutputStream.close();
            return Base64.getEncoder().encodeToString(byteArray);
        }
    }
}

来源：CSDN

作者：Vinting

链接：https://blog.csdn.net/Vinting/article/details/104344972