RSA非对称加密应用于前台js加密后台java解密

首先我们加密的时候都是使用对称加密，就是加密解密都是使用一套秘钥
非对称加密是指加密解密使用不同的秘钥

说明：本次记录的加密思路是后台java生成1 加密模块 2 加密公钥 3 加密秘钥其中公钥用于对字符串进行加密，秘钥用于对字符串进行解密，每次http请求后台将新生产的加密模块和加密公钥传送的前台，秘钥保存在后台。当前台使用公钥加密后，将数据传送到后台，后台再使用之前保存的秘钥进行解密。

注意：每次生成的1 加密模块 2 加密公钥 3 加密秘钥都是配套的，不能同上一次的加密模块来解密这一次的密文
效果
前台加密

后台解密(注释写错了…)

工具类：用于数据转换

package com.fh.util;

public class HexUtil {

    /**
     * 二进制byte数组转十六进制byte数组
     * byte array to hex
     *
     * @param b byte array
     * @return hex string
     */
    public static String byte2hex(byte[] b) {
        StringBuilder hs = new StringBuilder();
        String stmp;
        for (int i = 0; i < b.length; i++) {
            stmp = Integer.toHexString(b[i] & 0xFF).toUpperCase();
            if (stmp.length() == 1) {
                hs.append("0").append(stmp);
            } else {
                hs.append(stmp);
            }
        }
        return hs.toString();
    }

    /**
     * 十六进制byte数组转二进制byte数组
     * hex to byte array
     *
     * @param hex hex string
     * @return byte array
     */
    public static byte[] hex2byte(String hex)
             throws IllegalArgumentException{
        if (hex.length() % 2 != 0) {
            throw new IllegalArgumentException ("invalid hex string");
        }
        char[] arr = hex.toCharArray();
        byte[] b = new byte[hex.length() / 2];
        for (int i = 0, j = 0, l = hex.length(); i < l; i++, j++) {
            String swap = "" + arr[i++] + arr[i];
            int byteint = Integer.parseInt(swap, 16) & 0xFF;
            b[j] = new Integer(byteint).byteValue();
        }
        return b;
    }


     public static String bytesToHexString(byte[] src){
            StringBuilder stringBuilder = new StringBuilder("");
            if (src == null || src.length <= 0) {
                return null;
            }
            for (int i = 0; i < src.length; i++) {
                int v = src[i] & 0xFF;
                String hv = Integer.toHexString(v);
                if (hv.length() < 2) {
                    stringBuilder.append(0);
                }
                stringBuilder.append(hv);
            }
            return stringBuilder.toString();
        }
     private static byte charToByte(char c) {  
            return (byte) "0123456789ABCDEF".indexOf(c);  
        }
     public static byte[] hexStringToBytes(String hexString) {  
            if (hexString == null || hexString.equals("")) {  
                return null;  
            }  
            hexString = hexString.toUpperCase();  
            int length = hexString.length() / 2;  
            char[] hexChars = hexString.toCharArray();  
            byte[] d = new byte[length];  
            for (int i = 0; i < length; i++) {  
                int pos = i * 2;  
                d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));  
            }  
            return d;  
        }  

}

核心：RSA加密类

package com.fh.util;

import java.io.ByteArrayOutputStream;  
import java.io.FileInputStream;  
import java.io.FileOutputStream;  
import java.io.ObjectInputStream;  
import java.io.ObjectOutputStream;  
import java.math.BigInteger;  
import java.security.KeyFactory;  
import java.security.KeyPair;  
import java.security.KeyPairGenerator;  
import java.security.NoSuchAlgorithmException;  
import java.security.PrivateKey;  
import java.security.PublicKey;  
import java.security.SecureRandom;  
import java.security.interfaces.RSAPrivateKey;  
import java.security.interfaces.RSAPublicKey;  
import java.security.spec.InvalidKeySpecException;  
import java.security.spec.RSAPrivateKeySpec;  
import java.security.spec.RSAPublicKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;  

/** 
 * RSA 工具类。提供加密，解密，生成密钥对等方法。 
 * 需要到  下载bcprov-jdk14-123.jar。 
 *  
 */  



public class RSAUtils {
    private static final int MAX_ENCRYPT_BLOCK = 117; // RSA最大加密明文大小
    private static final int MAX_DECRYPT_BLOCK = 128; // RSA最大解密密文大小

    /**
     * 生成公钥和私钥
     *
     * @throws NoSuchAlgorithmException
     */
    public static KeyPair genRSAKeyPair() throws NoSuchAlgorithmException {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        keyPairGen.initialize(1024);
        return keyPairGen.generateKeyPair();
    }

    /**
     * 使用模和指数生成RSA公钥
     * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
     * /None/NoPadding】
     *
     * @param modulus  模
     * @param exponent 指数
     * @return
     */
    public static RSAPublicKey getPublicKey(String modulus, String exponent) {
        try {
            BigInteger b1 = new BigInteger(modulus, 16);
            BigInteger b2 = new BigInteger(exponent, 16);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
            return (RSAPublicKey) keyFactory.generatePublic(keySpec);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 使用模和指数生成RSA私钥
     * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
     * /None/NoPadding】
     *
     * @param modulus  模
     * @param exponent 指数
     * @return
     */
    public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
        try {
            BigInteger b1 = new BigInteger(modulus, 16);
            BigInteger b2 = new BigInteger(exponent, 16);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
            return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 公钥加密
     */
    public static byte[] encryptByPublicKey(byte[] data, RSAPublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        int inputLen = data.length;

        try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段加密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_ENCRYPT_BLOCK;
            }
            return out.toByteArray();
        }
    }

    /**
     * 私钥解密
     */
    public static String decryptByPrivateKey(byte[] encryptedData, RSAPrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        int inputLen = encryptedData.length;

        try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {

            int offSet = 0;
            byte[] cache;
            int i = 0;

            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }

            return new String(out.toByteArray(), "utf-8");
        }
    }

    /**
     * ASCII码转BCD码
     */
    public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
        byte[] bcd = new byte[asc_len / 2];
        int j = 0;
        for (int i = 0; i < (asc_len + 1) / 2; i++) {
            bcd[i] = asc_to_bcd(ascii[j++]);
            bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
        }
        return bcd;
    }

    public static byte asc_to_bcd(byte asc) {
        byte bcd;

        if ((asc >= '0') && (asc <= '9'))
            bcd = (byte) (asc - '0');
        else if ((asc >= 'A') && (asc <= 'F'))
            bcd = (byte) (asc - 'A' + 10);
        else if ((asc >= 'a') && (asc <= 'f'))
            bcd = (byte) (asc - 'a' + 10);
        else
            bcd = (byte) (asc - 48);
        return bcd;
    }

    /**
     * BCD转字符串
     */
    public static String bcd2Str(byte[] bytes) {
        char temp[] = new char[bytes.length * 2], val;

        for (int i = 0; i < bytes.length; i++) {
            val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
            temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0');

            val = (char) (bytes[i] & 0x0f);
            temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0');
        }
        return new String(temp);
    }

    /**
     * 拆分字符串
     */
    public static String[] splitString(String string, int len) {
        int x = string.length() / len;
        int y = string.length() % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        String[] strings = new String[x + z];
        String str = "";
        for (int i = 0; i < x + z; i++) {
            if (i == x + z - 1 && y != 0) {
                str = string.substring(i * len, i * len + y);
            } else {
                str = string.substring(i * len, i * len + len);
            }
            strings[i] = str;
        }
        return strings;
    }

    /**
     * 拆分数组
     */
    public static byte[][] splitArray(byte[] data, int len) {
        int x = data.length / len;
        int y = data.length % len;
        int z = 0;
        if (y != 0) {
            z = 1;
        }
        byte[][] arrays = new byte[x + z][];
        byte[] arr;
        for (int i = 0; i < x + z; i++) {
            arr = new byte[len];
            if (i == x + z - 1 && y != 0) {
                System.arraycopy(data, i * len, arr, 0, y);
            } else {
                System.arraycopy(data, i * len, arr, 0, len);
            }
            arrays[i] = arr;
        }
        return arrays;
    }
    //String 解密
 public static String Decrypt(String str,String mou,String m) throws Exception{
     //模hex
     String modulus =mou;
     //私钥指数hex
     String private_exponent = m;

     RSAPrivateKey priKey = getPrivateKey(modulus, private_exponent);

     return decryptByPrivateKey(HexUtil.hexStringToBytes(str), priKey);
 }
 //获取模块信息
 public static Map getModulus () throws NoSuchAlgorithmException{
     KeyPair keyPair = genRSAKeyPair();
     Map map = new HashMap();
     //生成公钥和私钥
     RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
     RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
     //模hex
     String modulus = publicKey.getModulus().toString(16);
     //公钥指数hex
     String public_exponent = publicKey.getPublicExponent().toString(16);
     //私钥指数hex
     String private_exponent = privateKey.getPrivateExponent().toString(16);
     map.put("g", public_exponent);
     map.put("m", private_exponent);
     map.put("modu", modulus);
    return map;
 }
    public static void main(String[] args) throws Exception {
        KeyPair keyPair = genRSAKeyPair();

        //生成公钥和私钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();


        //模hex
        String modulus = publicKey.getModulus().toString(16);
        //公钥指数hex
        String public_exponent = publicKey.getPublicExponent().toString(16);
        //私钥指数hex
        String private_exponent = privateKey.getPrivateExponent().toString(16);

        System.out.println("public_modulus: " + modulus);
        System.out.println("public_exponent: " + public_exponent);
        System.out.println("private_exponent: " + private_exponent);

        //明文
        String plaintStr = "123456";
        System.out.println("plaintStr: " + plaintStr);

        //使用模和指数生成公钥和私钥
        RSAPublicKey pubKey = getPublicKey(modulus, public_exponent);
        RSAPrivateKey priKey = getPrivateKey(modulus, private_exponent);
        //公钥加密后的密文
        byte[] encryptStr = encryptByPublicKey(plaintStr.getBytes("utf-8"), pubKey);
        System.out.println("encryptStr: " + HexUtil.bytesToHexString(encryptStr));
        String jmh = HexUtil.bytesToHexString(encryptStr);
        System.out.println("start");
        //私钥解密后的明文
        System.out.println("decryptStr: " + decryptByPrivateKey(HexUtil.hexStringToBytes(jmh), priKey));
    }

} 

业务逻辑类

//1
//声明加密秘钥
    private static String m;
//声明加密模块
    private static String mou;
//2
//调用RSA工具类的getModulus方法获取配套的公钥，秘钥，和加密模块信息，并将公钥和加密模块传送到前台，秘钥和加密模块
//保存到后台
    @ResponseBody
    @RequestMapping(value = "/getMoudle", method = RequestMethod.POST)
    public Object getMoudle() throws NoSuchAlgorithmException {
        Map jmInfo = RSAUtils.getModulus();
        String my = jmInfo.getString("m");
        m = my;
        mou = jmInfo.getString("modu");
        return jmInfo;
    }

//3
//使用之前保存的加密模块和秘钥进行解密
SAUtils.Decrypt(参数,mou,m)

4 js

//1
//映入js包
   <script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/jsbn.js"></script>
    <script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/jsbn2.js"></script>
    <script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/prng4.js"></script>
    <script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/rng.js"></script>
    <script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/rsa.js"></script>
    <script language="JavaScript" type="text/javascript" src="http://www-cs-students.stanford.edu/~tjw/jsbn/rsa2.js"></script>

//2声明加密对象
var RSADo = {
    "modulus":"",
    "publicExponent":""}
//2获取加密信息
function getModule(){
    mui.ajax("..../....", {
        data: {
        },
        dataType: 'json', //服务器返回json格式数据
        async: false,
        type: 'post', //HTTP请求类型
        timeout: 10000, //超时时间设置为10秒；
        success: function (data) {
            RSADo.modulus = data.modu;
            RSADo.publicExponent = data.g;
            privateKey = data.m;
        },
        error: function (xhr, type, errorThrown) {
        }
    });
   /* var str = "12345"
    var rsa = new RSAKey()
    rsa.setPublic(RSADo.modulus, RSADo.publicExponent)
    var encryptStr = rsa.encrypt(str);
    console.log('modulus：', RSADo.modulus);
    console.log('明文（explain）：', str)
    console.log('加密后（encrypt）：', encryptStr)
    // 解密
    rsa.setPrivate(RSADo.modulus, RSADo.publicExponent, privateKey)
    var decryptStr = rsa.decrypt(encryptStr)
    console.log('解密私钥：', privateKey)
    console.log('解密后（decrypt）', decryptStr)*/
})

//公钥加密方法
    function encryption(str){
        // 实例化js的RSA对象生成
        var rsa = new RSAKey()
        rsa.setPublic(RSADo.modulus, RSADo.publicExponent)
        var encryptStr = rsa.encrypt(str);
        return encryptStr;
    }

当然前台后台都是可以单独加密解密的。只要使用配套的加密信息就可以了