RSA解密，同样的代码在java中结果正常，Android中会在正确结果前面多出很多东西怎么回事？

qq_24683975 2020-10-06 10:14:27

jdk版本都是1.8（都是用的安装Android Studio时安装的jdk）
公钥：

MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCdHc7rWSuL8JCVRY0PwaeIsHX/gel/hvKA3zi5eH2C2bk9HFGbsNKX2Wg+rbXse0SfLLkF42gzD0ghlc7JeVC8DIJI4ef33UUjfcDyQ1xtsuFZDsIg4hFJPAeuaW0CNM1ydl2c2IzIiNL6AL0q736vkl0rqOS5IKw74/K2uQFcgQIDAQAB

私钥：

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

加密内容：

MGXvX+LVhDJPhrJXnZai6CDvg8Tgs8eIzFe0i5XKhmu5wcavibVjsYm1+3oMoXl3RfS07Vq1gM1hqWhTSb9EDP4wfFRVHDxhCQ3TDNOcJwf2bycoUBIQLjX0NySvocPRWGSNsVJYKNxyHOovrV1WEr1V9fMiO7u3jU6qO2XV1Us=

正确的解密结果：丬__
java代码：（网上复制的，然后自己加了个构造器）
因为Android中用java.util.Base64需要sdk26，但是我要兼容到sdk21，所以在java里面把下面这段代码打包成了jar然后直接调用的...

//

// Source code recreated from a .class file by IntelliJ IDEA

// (powered by Fernflower decompiler)

//



package MyBase64;



import java.security.KeyFactory;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.Signature;

import java.security.spec.PKCS8EncodedKeySpec;

import java.security.spec.X509EncodedKeySpec;

import java.util.Base64;

import javax.crypto.Cipher;



public class MyBase64 {

    public static final String KEY_ALGORITHM = "RSA";

    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    private static final int KEY_SIZE = 1024;

    private static final String PUBLIC_KEY = "RSAPublicKey";

    private static final String PRIVATE_KEY = "RSAPrivateKey";

    private static String str_pubK = "";

    private static String str_priK = "";



    public MyBase64(String pubK, String priK) {

        str_priK = priK;

        str_pubK = pubK;

    }



    public static PublicKey getPublicKey(String key) throws Exception {

        byte[] keyBytes = Base64.getDecoder().decode(key);

        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);

        KeyFactory keyFactory = KeyFactory.getInstance("RSA");

        PublicKey publicKey = keyFactory.generatePublic(keySpec);

        return publicKey;

    }



    public PrivateKey getPrivateKey(String key) throws Exception {

        byte[] keyBytes = Base64.getDecoder().decode(key);

        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);

        KeyFactory keyFactory = KeyFactory.getInstance("RSA");

        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);

        return privateKey;

    }



    public byte[] sign(byte[] data) throws Exception {

        PrivateKey priK = this.getPrivateKey(str_priK);

        Signature sig = Signature.getInstance("MD5withRSA");

        sig.initSign(priK);

        sig.update(data);

        return sig.sign();

    }



    public boolean verify(byte[] data, byte[] sign) throws Exception {

        PublicKey pubK = getPublicKey(str_pubK);

        Signature sig = Signature.getInstance("MD5withRSA");

        sig.initVerify(pubK);

        sig.update(data);

        return sig.verify(sign);

    }



    public byte[] encrypt(byte[] bt_plaintext) throws Exception {

        PublicKey publicKey = getPublicKey(str_pubK);

        Cipher cipher = Cipher.getInstance("RSA");

        cipher.init(1, publicKey);

        byte[] bt_encrypted = cipher.doFinal(bt_plaintext);

        return bt_encrypted;

    }



    public byte[] decrypt(String bt_encrypted) throws Exception {

        PrivateKey privateKey = this.getPrivateKey(str_priK);

        Cipher cipher = Cipher.getInstance("RSA");

        cipher.init(2, privateKey);

        return cipher.doFinal(Base64.getDecoder().decode(bt_encrypted));

    }



    public static void main(String[] args) throws Exception {

        String pub = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCdHc7rWSuL8JCVRY0PwaeIsHX/gel/hvKA3zi5eH2C2bk9HFGbsNKX2Wg+rbXse0SfLLkF42gzD0ghlc7JeVC8DIJI4ef33UUjfcDyQ1xtsuFZDsIg4hFJPAeuaW0CNM1ydl2c2IzIiNL6AL0q736vkl0rqOS5IKw74/K2uQFcgQIDAQAB";

        String pri = "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";

        String string = "MGXvX+LVhDJPhrJXnZai6CDvg8Tgs8eIzFe0i5XKhmu5wcavibVjsYm1+3oMoXl3RfS07Vq1gM1hqWhTSb9EDP4wfFRVHDxhCQ3TDNOcJwf2bycoUBIQLjX0NySvocPRWGSNsVJYKNxyHOovrV1WEr1V9fMiO7u3jU6qO2XV1Us=";

        System.out.println(new String((new MyBase64(pub, pri)).decrypt(string)));

    }

}