diff --git a/index.js b/index.js
index 76d715c..21db641 100644
--- a/index.js
+++ b/index.js
@@ -5,12 +5,13 @@ const { v4: uuidv4 } = require("uuid");
 const app = express();
 const axios = require("axios");
 const port = 8080;
+const validApiKey = process.env.PASSWORD;
 
 axios.defaults.headers.common["User-Agent"] = process.env.USER_AGENT;
 axios.defaults.headers.common["Cookie"] = process.env.YOUCOM_COOKIE;
 
 
-app.post("/v1/messages", (req, res) => {
+app.post("/v1/messages", apiKeyAuth, (req, res) => {
 	req.rawBody = "";
 	req.setEncoding("utf8");
 
@@ -99,7 +100,7 @@ app.post("/v1/messages", (req, res) => {
 
 
 				// 试算用户消息长度
-				if(encodeURIComponent(JSON.stringify(userMessage)).length + encodeURIComponent(userQuery).length > 32000) { 
+				if(encodeURIComponent(JSON.stringify(userMessage)).length + encodeURIComponent(userQuery).length > 32000) {
 					//太长了，需要上传
 
 					// user message to plaintext
@@ -281,8 +282,24 @@ app.use((req, res, next) => {
 
 app.listen(port, () => {
 	console.log(`YouChat proxy listening on port ${port}`);
+	if (!validApiKey) {
+		console.log(`Proxy is currently running with no authentication`)
+	}
 });
 
+function apiKeyAuth(req, res, next) {
+	const reqApiKey = req.header('x-api-key');
+
+	if (validApiKey && (reqApiKey !== validApiKey)) {
+		// If Environment variable PASSWORD is set AND x-api-key header is not equal to it, return 401
+		const clientIpAddress = req.headers['x-forwarded-for'] || req.ip;
+		console.log(`Receviced Request from IP ${clientIpAddress} but got invalid password.`);
+		return res.status(401).json({error: 'Invalid Password'});
+	}
+
+	next();
+}
+
 // eventStream util
 function createEvent(event, data) {
 	// if data is object, stringify it
@@ -305,11 +322,11 @@ function createDocx(content) {
 		sections: [
 			{
 				properties: {},
-				children: 
+				children:
 					paragraphs
 				,
 			},
 		],
 	});
 	return docx.Packer.toBuffer(doc).then((buffer) => buffer);
-}
\ No newline at end of file
+}
diff --git a/usage.md b/usage.md
index e227417..95b9b80 100644
--- a/usage.md
+++ b/usage.md
@@ -12,11 +12,13 @@
 
 6. 编辑 `start.bat` 文件，把上面的 Cookie 和 User Agent 粘贴进去
 
-7. 启动 start.bat
+7. （可选）如果需要，您可以仿照第6步在`start.bat`中设定一个名为 "PASSWORD" 的环境变量，并将其用作密码。如果没有定义该环境变量，程序将接受所有传入的请求，而不进行任何身份验证
 
-8. 酒馆中选择 Claude，反向代理地址填 http://127.0.0.1:8080/v1 反代密码必须填，随便什么都可以。
+8. 启动 start.bat
 
-9. 开始使用。如果失败了/没有结果/403/Warning 就多重试几次。
+9. 酒馆中选择 Claude，反向代理地址填 http://127.0.0.1:8080/v1 **反代密码必须填, 同时打开流式传输**，随便什么都可以（除非你在第7步设置了PASSWORD）。
+
+10. 开始使用。如果失败了/没有结果/403/Warning 就多重试几次。
 
 ## 注意事项
 
@@ -36,12 +38,14 @@
 
 6. Edit the `start.bat` file and paste the cookie and User Agent into it.
 
-7. Start start.bat
+7. (Optional) you can set an environment variable named `PASSWORD` in `start.bat`, similar to Step 6, and use it as the password. If this environment variable is not defined, the program will accept all incoming requests without performing any authentication.
 
-8. Select Claude in the Tavern and put http://127.0.0.1:8080/v1 as the address of the reverse proxy. Use any random string for password.
+8. Start start.bat
 
-9. Enjoy it. If it fails/no result/403/Warning, try again.
+9. Select Claude in the Tavern and put http://127.0.0.1:8080/v1 as the address of the reverse proxy. **Use any random string for password, also turn on Streaming** (unless you set PASSWORD in step 7).
+
+10. Enjoy it. If it fails/no result/403/Warning, try again.
 
 ## Caution
 
-If you get 403 errors, consider getting the cookie again or changing your IP.
\ No newline at end of file
+If you get 403 errors, consider getting the cookie again or changing your IP.