首先简单明确一下对称加密和非对称加密之间的区别：
对称加密：即加密解密使用的是同一个密钥；
非对称加密：即生成两个密钥，加密时使用公钥，解密是使用的私钥；
说明：本次实践的加密操作主要生成以下三个关键对象
1.加密模块
2.加密公钥
3.加密私钥
思路：公钥的作用是加密指定字符串；私钥则是解密指定字符串；每次前台发送http请求至后台都将新生成加密模块、加密公钥、加密私钥，而公钥和加密模块则会送到前台对数据进行加密；私钥则保留在后台等待。当前台使用公钥加密过后，将数据传输到后台，再使用保留的私钥进行解密。
注意： 每次生成的 加密模块、加密公钥、加密私钥 都是组合产生的，非同一次产生的，将会包解密失败的错误！
下面我对于前台后台所有的加解密的情况做汇总，根据实际开发情况做灵活变通：
工具类：新建工具类，用于数据转换
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
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;
}
JS页面发送请求
//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":""}
//3获取加密信息
$(function() {
$("#denglu").bind("click", function() {
$.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;
var userName = $("#userName").val();
var possWord = $("#iptPwd").val();
//使用获取到的公钥加密
var rsa = new RSAKey();
rsa.setPublic(RSADo.modulus, RSADo.publicExponent);
var Name = rsa.encrypt(userName);
var pwd = rsa.encrypt(possWord);
console.log('加密后（name）：', Name);
console.log('加密后（pwd）：', pwd);
//私钥解密
//通常不会在前台拿到私钥并解密，只是把这个情况罗列出来
//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)
//当前账号密码设置为RSA加密后的状态，否则依旧会将明文暴露出来
$('#userName').val(Name);
$('#iptPwd').val(pwd);
//执行提交功能，再次进入后台
$('#form').submit();
},
error: function (xhr, type, errorThrown) {
}
});
});
//声明公钥加密方法
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;
}
部分相对久远的框架，可能直接把业务逻辑类放在加密类中一并执行
注意这个声明的静态属性，用于存放密钥和加密模块
部分框架请求针对前台请求不能单纯的抛出异常而是捕获异常，以及返回类型需要封装成json串返回才不会出错，奇奇怪怪的问题不少
//声明加密秘钥
private static String m;
//声明加密模块
private static String mou;
@Action
public String getModule() {
Map jmInfo = new HashMap();
try {
jmInfo = MainPage.getModulus();
String my = jmInfo.get("m").toString();
m = my;
mou = jmInfo.get("modu").toString();
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
JSONObject json = new JSONObject();
json.putAll(jmInfo);
return json.toString();
}
对应上面的main方法全部情况的汇总，再做一个简化
public static void main(String[] args) throws Exception {
HttpServletRequest req = ActionContext.getActionContext().getHttpServletRequest();
HttpServletResponse resp = ActionContext.getActionContext().getHttpServletResponse();
String userName = req.getParameter(System.getProperty(用户名));
String possWord = req.getParameter(System.getProperty(密码));
//做个账号、密码的非空判断
if(!StringUtility.isNullOrEmpty(userName) && !StringUtility.isNullOrEmpty(possWord)) {
//通常情况下，我们已经不需要再进行二次getMoudles()方法来建立密钥了
//应该直接应用上面存储的静态属性（私钥--m，加密模块--mou）
//否则将会出现解密失败的错误，因为再次创建就是两套密钥了
//使用模和指数生成私钥
RSAPrivateKey priKey = getPrivateKey(mou, m);
System.out.println("开始解密");
//私钥解密后的明文
System.out.println("decryptName: " + decryptByPrivateKey(HexUtil.hexStringToBytes(Name), priKey));
System.out.println("decryptPwd: " + decryptByPrivateKey(HexUtil.hexStringToBytes(Pwd), priKey));
String decryptName = decryptByPrivateKey(HexUtil.hexStringToBytes(userName), priKey);
String decryptPwd = decryptByPrivateKey(HexUtil.hexStringToBytes(possWord), priKey);
//之后拿着解密的账号密码，该验证验证，通过则登录就可以了
}
}
这篇总结的比较细，主要明确生产一套密钥，那就在这一套密钥内进行加解密操作就可以了，若在再懵懵叨叨的在主程序里面new一套密钥，那绝对无法匹配的。
当然大部分情况都是前台请求获取加密模块和公钥，而私钥和加密模块则保存在定义的静态属性中；在登录的时候将数据传到后台进行确认，直接调用该静态属性解密即可；文章总结了所有情况的加解密也是为了情况的多样性，以防不时之需~