一、客户端(APP)和服务端验签机制
1.背景
在以前传统项目中,当用户输入完正确的用户名和密码之后,服务端会在session存入用户的信息,即客户端登录成功后,服务端给其分配一个sessionId,返回给客户端,以后每次客户端请求带着sessionId。这种方式进行交互的时候必然存在安全风险,上述登录流程, 我们服务器判断用户的登录状态, 完全依赖于sessionId,一旦其被截获, 黑客就能够模拟出用户的请求。例如(我们产品中以前真实发生过的):现在wifi随处可见,用户通过wifi连接到公网,请求我们服务器,这样在外连接不安全的wifi的时候,黑客就有机可趁了,他通过网络传输工具,在用户登录我们APP之后,拦截获取到我们传给客户端的sessionId;并通过用户在APP中的操作,抓取到一些关键性的请求地址,进行伪造攻击。
基于此,我引入了当时比较流行的解决方案,通过RAS秘钥对加密并引入token机制,防止被恶意拦截攻击。方案如下:
1)客户端在第一次进入的时候会进行初始化,服务端通过RSA生产秘钥对A,私钥A存在服务端,公钥A传给客户端;
2)用户在登录时,将密码用公钥A进行RSA加密,并初始化RSA秘钥对B,将公钥B,用户名,加密后的密码传给服务端。服务端通过私钥A进行解密验证密码,通过后生产唯一字符串token,并通过公钥B进行加密token和session一起传给客户端;
3)客户端通过私钥B进行解密获得真正的token,存在上下文中,以后每次请求,都用公钥A进行加密传给服务端进行验证
这样,就算被拦截,黑客获取到的都是密文,直接用户伪造请求服务端的校验会报错,解密??呵呵(破解这算法要买最好的计算机和花几个月长则几年的时间,取决于你秘钥的长度),难道太大,成本太高,黑客也会放弃攻击的。(就像爬虫和反爬虫,当爬虫成本远大于收益的时候,爬虫者也会放弃爬去该网站(保护成功),反正人家不爬你爬谁)
二、RSA加密(JAVA端实现)
package com.xiatian.scb.demo.util;
import org.springframework.util.Base64Utils;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
/**
* 〈一句话功能简述〉<br>
* 〈功能详细描述〉
*
* @author 18043622 2018/8/22
* @see [相关类/方法](可选)
* @since [产品/模块版本] (可选)
*/
public class RSAUtils {
/** *//**
* 加密算法RSA
*/
public static final String KEY_ALGORITHM = "RSA";
/** *//**
* 签名算法
*/
public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
/** *//**
* 获取公钥的key
*/
private static final String PUBLIC_KEY = "RSAPublicKey";
/** *//**
* 获取私钥的key
*/
private static final String PRIVATE_KEY = "RSAPrivateKey";
/** *//**
* RSA最大加密明文大小
*/
private static final int MAX_ENCRYPT_BLOCK = 117;
/** *//**
* RSA最大解密密文大小
*/
private static final int MAX_DECRYPT_BLOCK = 128;
/** *//**
* <p>
* 生成密钥对(公钥和私钥)
* </p>
*
* @return
* @throws Exception
*/
public static Map<String, Object> genKeyPair() throws Exception {
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
Map<String, Object> keyMap = new HashMap<>(2);
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
/** *//**
* <p>
* 用私钥对信息生成数字签名
* </p>
*
* @param data 已加密数据
* @param privateKey 私钥(BASE64编码)
*
* @return
* @throws Exception
*/
public static String sign(byte[] data, String privateKey) throws Exception {
byte[] keyBytes = Base64Utils.decodeFromString(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(privateK);
signature.update(data);
return Base64Utils.encodeToString(signature.sign());
}
/** *//**
* <p>
* 校验数字签名
* </p>
*
* @param data 已加密数据
* @param publicKey 公钥(BASE64编码)
* @param sign 数字签名
*
* @return
* @throws Exception
*
*/
public static boolean verify(byte[] data, String publicKey, String sign)
throws Exception {
byte[] keyBytes = Base64Utils.decodeFromString(publicKey);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
PublicKey publicK = keyFactory.generatePublic(keySpec);
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(publicK);
signature.update(data);
return signature.verify(Base64Utils.decodeFromString(sign));
}
/** *//**
* <P>
* 私钥解密
* </p>
*
* @param encryptedData 已加密数据
* @param privateKey 私钥(BASE64编码)
* @return
* @throws Exception
*/
public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
throws Exception {
byte[] keyBytes = Base64Utils.decodeFromString(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, privateK);
int inputLen = encryptedData.length;
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;
}
byte[] decryptedData = out.toByteArray();
out.close();
return decryptedData;
}
/** *//**
* <p>
* 公钥解密
* </p>
*
* @param encryptedData 已加密数据
* @param publicKey 公钥(BASE64编码)
* @return
* @throws Exception
*/
public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
throws Exception {
byte[] keyBytes = Base64Utils.decodeFromString(publicKey);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicK = keyFactory.generatePublic(x509KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, publicK);
int inputLen = encryptedData.length;
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;
}
byte[] decryptedData = out.toByteArray();
out.close();
return decryptedData;
}
/** *//**
* <p>
* 公钥加密
* </p>
*
* @param data 源数据
* @param publicKey 公钥(BASE64编码)
* @return
* @throws Exception
*/
public static byte[] encryptByPublicKey(byte[] data, String publicKey)
throws Exception {
byte[] keyBytes = Base64Utils.decodeFromString(publicKey);
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicK = keyFactory.generatePublic(x509KeySpec);
// 对数据加密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, publicK);
int inputLen = data.length;
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;
}
byte[] encryptedData = out.toByteArray();
out.close();
return encryptedData;
}
/** *//**
* <p>
* 私钥加密
* </p>
*
* @param data 源数据
* @param privateKey 私钥(BASE64编码)
* @return
* @throws Exception
*/
public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
throws Exception {
byte[] keyBytes = Base64Utils.decodeFromString(privateKey);
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, privateK);
int inputLen = data.length;
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;
}
byte[] encryptedData = out.toByteArray();
out.close();
return encryptedData;
}
/** *//**
* <p>
* 获取私钥
* </p>
*
* @param keyMap 密钥对
* @return
* @throws Exception
*/
public static String getPrivateKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PRIVATE_KEY);
return Base64Utils.encodeToString(key.getEncoded());
}
/** *//**
* <p>
* 获取公钥
* </p>
*
* @param keyMap 密钥对
* @return
* @throws Exception
*/
public static String getPublicKey(Map<String, Object> keyMap)
throws Exception {
Key key = (Key) keyMap.get(PUBLIC_KEY);
return Base64Utils.encodeToString(key.getEncoded());
}
public static void main(String[] args) throws Exception {
Map<String, Object> keyMap = RSAUtils.genKeyPair();
// 测试RSA
System.err.println("公钥加密——私钥解密");
String source = "我喜欢大灰狼,啦啦啦,大灰狼。密文你看不懂哦";
System.out.println("\r加密前文字:\r\n" + source);
byte[] data = source.getBytes();
byte[] encodedData = RSAUtils.encryptByPublicKey(data, RSAUtils.getPublicKey(keyMap));
System.out.println("加密后文字:\r\n" + Base64Utils.encodeToString(encodedData));
byte[] decodedData = RSAUtils.decryptByPrivateKey(encodedData, RSAUtils.getPrivateKey(keyMap));
String target = new String(decodedData);
System.out.println("解密后文字: \r\n" + target);
}
}
输出结果:
加密前文字:
我喜欢大灰狼,啦啦啦,大灰狼。密文你看不懂哦
加密后文字:
Ap7sY2UnWyfKgqq+SgXDEH8u0XwmybDzdC+o4O2QQl+3aEYz5aUJpGJH7qoxQaEEwkEJMGGeKo6rkXlvi6j+2zJ56CBO34dyq9R6bc2eCZgcz21ghclKHYkOCOTkpKUh9g7BkjFIiUgtrrARlVMt1CmTVtEFn+ToyWq+K6/R3ms=
解密后文字:
我喜欢大灰狼,啦啦啦,大灰狼。密文你看不懂哦
这样 黑客最多得到密文,他也看不懂的啦
其实,以上token机制为了以防万一(黑客在用户手机上装了流氓软件,解开了token明文)。我们也可以做一个token失效机制,每隔5分钟就更新token一次(失效的token不能通过校验),做个保护。