RSA加密\解密，数据传输的安全性

开遍之前,给大家推荐一本书, <图解密码技术(日)结城浩(著)完整版> , 读完该书 , 会对加密算法有一个较为深刻的了解.
如下只是我对RSA和SHA1WITHRSA的笔记和理解,后附上实现的代码,代码仅仅是Android和PHP的,如果有疏忽遗漏,请各位批评指出.
一.RSA
以图来说话:

如何生成对应的公私钥呢? , 详见上一篇文章《RSA公钥和私钥的生成(PHP\Android\iOS),数据传输的安全性》

以下代码为rsa加解密代码,非sha1withrsa代码

以下为Android代码:

/**
 * Android加密和解密 , 请求**
 * Created by xiaojun.lan on 2017/1/22.
 */

import android.util.Base64;
import android.util.Log;

import com.lxj.ucapp.common.utils.LogUtils;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

/**
 * 注意:
 * 本文件是对用户需要加密信息进行加密的文件,请确保本文件安全性,注意反编译读取公私钥
 */
public class Rsa2 {

    //加密 , 公钥 , 保密 , API加密使用,内容已经打乱,请重新生成,rsa_public_key.pem的内容
    //这个公钥和下面的私钥并不对应,这个公钥的私钥保存在服务器
    private static final String RSA_PUBLICE =
            "MIGSDFSDFUAA4GNADCBiQKBgQCbxDvCxOwLNJnBBBBBU6YTpuEFjKEuW\n" +
                    "MKze56Zs0OgRj9FU6K9w3OSDFASDFuELOQgh4Soy84CQy0h7Ep3zBBBBjQ5i+dPksn\n" +
                    "cMQ0q9aAN/x69BSSDFGSDFGDFGCY5974hldSDFEEtm0opzbblJ+x7AS2Uu5hhBBB1X8oLHf1E\n" +
                    "8A8Cylf5LWkiJkVvRTGSDFjQIDAADFAJK,BNJFK";

    //解密 , 私钥 , 绝密 以下私钥只是一个说明,已经打乱其内容,请重新生成,pkcs8_private_key.pem的内容
    //这个私钥的公钥和上面并不对应,这个私钥对应的公钥在服务器
    private static final String RSA_PRIVATE = "CVGHJT67UGHMVBNMUY67867CAmEwggJdAgEAAoGBAMBlEwCEkrqdG/EH\n" +
            "sj284Oa04jM5wYTMtcUb2exV9o7mMZJj7iMtR3Yf/1pEAi51IKEH5d6ALrN4WZMF\n" +
            "OB5R3ffuHL8ojFAoOa56fdqIZrpUCP2YnNT8JB1xjPL159foth31IqlO4T6MIaIr\n" +
            "4LC3zsASDFASDWE34567UY78I3421DFGHUIOL878564IY9KkzpUW9EYD5DKBG3ND\n" +
            "VQcnSEwuwRo7cH35i5iNVAIriRn+R7S3qJapYUUIkI6SLrmDe5pf2fI//izv8ohr\n" +
            "EjrOyveQ4nnMZcWEskGtyi96E54HJMCVBSAERTW3435e2OvigGjCOI5kskYzHw9v\n" +
            "4O1asOaLeFqoj8DmHQJBAPHdeViJn7dYuFStbMp28cThz9jGn1f9pn4fUVs5h+5X\n" +
            "OjuPmT0WGo4pCnrPhE7YGJ1pen4/H3LF1OvAWIg60ucCQQDLo3qG88Vp1FP/PKnR\n" +
            "VtQrIEZAd5+v4yz5jni51Q+83n1wcERUeM65w+6SmsypfxYoscXPMffWxhoMtBB3\n" +
            "yzArAkEAwxpHApax0fKtbxEeiwv75zfItDM04oPoRCD7Pb1g23BdtyIVGOO1tCuD\n" +
            "GqI/NmK3KHOnriM5ORpAsZPNVscszQJAVgxtYQsvFyoWmFrc8016eAK6TNF/k8Yu\n" +
            "IgHW98eVT9zAKrv106/8wriNXju1UcYW6fk8ufHGZWXuagHIl6YvYwJBAN+w3TnG\n" +
            "rSvrqO+ZBkXABx23NuIcOWE+30CQkm6a+g9tYBNbbGHJKFTYU899-0T678454567\n" +
            "A1LcWyf6fO236YUJ,KBNKT7UI";

    private static final String RSA = "RSA";

    private static final String TAG = "Rsa";


    /**
     * 使用公钥加密
     *
     * @param content 需要加密数据
     * @return 加密后的结构
     */
    public static String encryptByPublic(String content) {

        try {
            PublicKey pubkey = getPublicKeyFromX509(RSA, RSA_PUBLICE);
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.ENCRYPT_MODE, pubkey);
            byte plaintext[] = content.getBytes("UTF-8");
            byte[] output = cipher.doFinal(plaintext);
            return new String(Base64.encode(output, Base64.DEFAULT));
        } catch (Exception e) {
            return "";
        }
    }

    /**
     * 通过私钥解密
     *
     * @param content 需要解密的数据
     * @return 解密后的数据
     */
    public static String decryptByPrivate(String content) {
        if (content == null || content.length() < 4) {
            LogUtils.LogError(TAG, "需要解密的数据有误");
            return "";
        }
        try {
            PrivateKey prikey = getPrivateKeyFromPKCS8(RSA, RSA_PRIVATE);
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, prikey);
            byte[] enBytes = Base64.decode(content, Base64.DEFAULT);
            byte[] deBytes = cipher.doFinal(enBytes);
            return new String(deBytes);
        } catch (Exception e) {
            LogUtils.LogError(TAG, "数据解密失败,返回null");
            return "";
        }
    }

    /**
     * 将字符串进行urlencode转换,使得其在网络传输中不会乱码
     * @param str 需要转换的字符串
     * @return 转换后的结果
     */
    public static String rsaUrlEncode(String str) {
        String urlEncode_str = null;
        try {
            urlEncode_str = URLEncoder.encode(str, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            LogUtils.LogError(TAG, str + "参数 url 转码失败");
            e.printStackTrace();
        }
        return urlEncode_str;
    }

    /**
     * 得到公钥
     *
     * @param RSA    "rsa"
     * @param bysKey "公钥字符串"
     * @return 返回公钥
     */
    private static PublicKey getPublicKeyFromX509(String RSA, String bysKey) {
        byte[] decodedKey = Base64.decode(bysKey, Base64.DEFAULT);
        X509EncodedKeySpec x509 = new X509EncodedKeySpec(decodedKey);
        KeyFactory keyFactory;
        PublicKey publicKey = null;
        try {
            keyFactory = KeyFactory.getInstance(RSA);
            publicKey = keyFactory.generatePublic(x509);
        } catch (NoSuchAlgorithmException e) {
            Log.e(TAG, "keyFactory出错");
            e.printStackTrace();
        } catch (InvalidKeySpecException e) {
            Log.e(TAG, "publicKey出错,请检查公钥是否正确");
            e.printStackTrace();
        }
        return publicKey;
    }

    /**
     * 得到私钥
     *
     * @param RSA    "rsa"
     * @param bysKey "私钥字符串"
     * @return 返回私钥
     */
    private static PrivateKey getPrivateKeyFromPKCS8(String RSA, String bysKey) {
        byte[] keyBytes;
        keyBytes = Base64.decode(bysKey, Base64.DEFAULT);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory;
        PrivateKey privateKey = null;
        try {
            keyFactory = KeyFactory.getInstance(RSA);
            privateKey = keyFactory.generatePrivate(keySpec);
        } catch (NoSuchAlgorithmException e) {
            Log.e(TAG, "keyFactory异常");
        } catch (InvalidKeySpecException e) {
            Log.e(TAG, "privateKey出错,请检查是否是PKCS8格式的私钥");
            e.printStackTrace();
        }
        return privateKey;
    }

}

调用方法:

使用公钥加密:
Rsa.rsaUrlEncode(//将内容进行urlencode处理
    Rsa.encryptByPublic("aaaaaa")//加密
)

使用私钥解密:
Rsa.decryptByPrivate(
    Rsa.rsaUrlEncode("asdfaskdlfjaksdf加密内容")//对内容进行urldecode处理
)//解密

---

以下为PHP服务器端:

<?php

/**
 * Class Rsa
 * create by xiaojun.lan on 2016.09.12
 */
class Rsa {

    /**
     * 客户端公钥加密
     * 该数据加密后,将发送给客户端,客户端使用本函数使用的公钥对应的私钥进行解密
     * @param string $data
     * @return null|string
     */
    public static function publicEncrypt($data = '') {
        if (! is_string ( $data )) {
            return null;
        }
        return openssl_public_encrypt ( $data, $encrypted, self::getPublicKey () ) ? base64_encode ( $encrypted ) : null;
    }

    /**
     * 解密客户端发送过来的加密数据
     * 私钥解密
     *
     * @param string $encrypted
     * @return null
     */
    public static function privDecrypt($encrypted = '') {
        if (! is_string ( $encrypted )) {
            return null;
        }
        return (openssl_private_decrypt ( base64_decode ( $encrypted ), $decrypted, self::getPrivateKey () )) ? $decrypted : null;
    }

    /**
     * 获取客户端私钥
     * 本私钥对应的公钥向客户端公开,客户端使用公钥加密后,统一使用该私钥进行解密
     * 
     * @return bool|resource
     */
    private static function getPrivateKey() {
        $privKey = file_get_contents("./rsa_private_key.pem");
        return openssl_pkey_get_private ( $privKey );
    }

    /**
     * 获取客户端对应的公钥
     * 该公钥是客户端私钥解密对应的公钥   
     * 
     * @return bool|resource
     */
    private static function getPublicKey() {
        $publicKey = file_get_contents("./rsa_public_key.pem");
        return openssl_pkey_get_public ( $publicKey );
    }

}

调用方法:

//$_POST['name']是移动端传过来的经过urlencode处理的加密串
//$name 是要加密的字符串

Rsa::privDecrypt($_POST['name'])//解密
Rsa::publicEncrypt($name)//加密

由于本人对iOS不是很熟悉,暂时未上iOS代码,如果有可提供的同学,可以提供下

福利:
图解密码技术文档 <图解密码技术(日)结城浩(著)完整版.pdf>
http://download.csdn.net/download/xkjscm/10044301