diff --git a/.gitignore b/.gitignore
index 45cef44..9429944 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,4 +19,8 @@
 *.code-workspace
 
 # Local History for Visual Studio Code
-.history/
\ No newline at end of file
+.history/
+
+# Other Runtime-Generated Files
+*.crt
+*.key
diff --git a/README.md b/README.md
index 5eca354..94a8da4 100644
--- a/README.md
+++ b/README.md
@@ -2,55 +2,37 @@
 
 RVPN Web Portal Proxy Adapter (based on MITM)
 
-尝试将[浙江大学 RVPN 网页版](https://rvpn.zju.edu.cn)模拟成一个 HTTP 代理。
+因为不想在电脑上安装 EasyConnect，所以做了一个访问 ZJU 校内网站的轻量级方案——将 [浙江大学 RVPN 网页版](https://rvpn.zju.edu.cn) 模拟为本地 HTTP 代理。
 
-提出这个想法的讨论：[有没有将 CGI Proxy 转化为普通 HTTP Proxy 的工具呢？ - V2EX](https://www.v2ex.com/t/670356)
+## 使用
+
+1. 前往 [Releases](https://github.com/CoolSpring8/rwppa/releases/) 下载并放于合适位置；
+2. 运行，输入上网服务账号、密码（即用于校内拨号 VPN 的账号）以及监听端口（如“127.0.0.1:8080”代表监听 8080 端口，仅接受本机流量）。账号密码仅会被发送至 rvpn.zju.edu.cn，用于登录认证。
+3. 点击登录后别着急，先将程序同目录下生成的 rootCA.crt 安装至“受信任的根证书颁发机构”存储区。（之后运行不需要这一步）
+4. 用 SwitchyOmega 等设置好代理，start browsing！
+
+注意不要删除 rootCA.crt 和 rootCA.key，否则需要重新添加信任。
 
 ## 特性及局限
 
 ### 特性：
 
-- 配置完毕并登录后，可访问校内校外 HTTP / HTTPS 网站（例如 CC98，正版软件服务与管理平台等），原理基于模拟 RVPN 网页版。
-- 支持 HTTP 的 GET，POST，PUT，DELETE，HEAD 方法，一定程度上支持 OPTIONS 方法（模拟）。
+- 配置完毕并登录后，可访问校内校外 HTTP / HTTPS 网站（例如 CC98，正版软件服务与管理平台等）。
+- 支持 HTTP 的 GET，POST，PUT，DELETE，HEAD 方法，一定程度上支持 OPTIONS 方法（仅为模拟）。
+- 正确处理大部分网页及网页资源。如果碰到问题，欢迎提 Issue/PR ！
 
 ### 局限：
 
-- **不支持 WebSocket，FTP，SSH等非 HTTP 协议。**
+- **不支持 WebSocket，FTP，SSH等非 HTTP 协议。**你可能会想了解 [Hagb/docker-easyconnect](https://github.com/Hagb/docker-easyconnect) 项目。
 - 不支持 HTTP 的 PATCH 等方法。
 - OPTIONS 方法由于 RVPN 网页版不支持，所以实际不会向服务器发送请求，而是由 rwppa 直接返回一个针对 CORS 预检而配置的较为宽松的结果，安全性有所降低。
-- 不支持 TLS 1.3 Early Data（0-RTT）。若原网站启用过 TLS 1.3 Early Data且 session ticket 还没过期则会[无法访问](https://golang.org/src/crypto/tls/handshake_server_tls13.go)（如 V2EX）。（但是短期内大概不会有开启这个特性的校内网站吧。）
-
-## 使用
-
-1. ```bash
-   openssl genrsa -out rootCA.key 4096
-   ```
-
-2. ```bash
-   openssl req -x509 -new -nodes -key rootCA.key -sha256 -days 1024 -out rootCA.crt
-   ```
-
-3. 把 rootCA.crt 安装到受信任证书存储区；
-
-4. 将 rootCA.key 和 rootCA.crt 的内容填入 cert.go；
-
-5. ```
-   go build
-   ```
-
-6. 在浏览器登录 rvpn.zju.edu.cn，从 Cookies 中找到 TWFID 字段的值；
-
-7. ```
-   ./rwppa
-   ```
-
-1~4 是可选的。你也可以信任并使用 cert.go 自带的证书，但出于安全性考虑不推荐这样做。
-
-由于使用了 Fyne GUI，现在编译还需要 GCC 等额外依赖。
+- 不支持 TLS 1.3 Early Data（0-RTT）。若原网站启用过 TLS 1.3 Early Data 且 session ticket 还没过期则会[无法访问](https://golang.org/src/crypto/tls/handshake_server_tls13.go)（如 V2EX）。（但是短期内大概不会有开启这个特性的校内网站吧。）
 
 ## 其他
 
-欢迎 PR 改进！
+提出这个想法的最初讨论：[有没有将 CGI Proxy 转化为普通 HTTP Proxy 的工具呢？ - V2EX](https://www.v2ex.com/t/670356)
+
+欢迎提出 Issue 或 PR！
 
 ## LICENSE
 
diff --git a/cert.go b/cert.go
index 128028d..0df0bcd 100644
--- a/cert.go
+++ b/cert.go
@@ -31,95 +31,84 @@
 package main
 
 import (
+	"crypto/rand"
+	"crypto/rsa"
 	"crypto/tls"
 	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"io/ioutil"
+	"math/big"
+	"os"
+	"time"
 
 	"github.com/elazarl/goproxy"
 )
 
-var caCert = []byte(`-----BEGIN CERTIFICATE-----
-MIIFazCCA1OgAwIBAgIUdWndr4j2nJH3C+DfjL0sqG8PIMQwDQYJKoZIhvcNAQEL
-BQAwRTELMAkGA1UEBhMCQVUxEzARBgNVBAgMClNvbWUtU3RhdGUxITAfBgNVBAoM
-GEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDAeFw0yMDA2MTgwNzQ1NDBaFw0yMzA0
-MDgwNzQ1NDBaMEUxCzAJBgNVBAYTAkFVMRMwEQYDVQQIDApTb21lLVN0YXRlMSEw
-HwYDVQQKDBhJbnRlcm5ldCBXaWRnaXRzIFB0eSBMdGQwggIiMA0GCSqGSIb3DQEB
-AQUAA4ICDwAwggIKAoICAQDHiQ7JbOCvmEw+VYQY+4iLwtTHe9GyH3zXYujeeqC5
-rcBU5MBD8NyqBjSDi/JPXEiCpBkYzmDtmqiCEmuoi8r6LADoJUdo2QUzu+S9UVt7
-FqgXRNzZC5Enh1F9m/pkyz7+GtuQB4PIQGf74FNlza5Bd+9NmJrDYKxj6ydXoXTS
-hTQrMEx3Wy8PzqpJw1006/So8Nh4jeu41DJr43bcO2J09/MpOd9pzB2GiDgrHu5M
-5EAUJONWut62oWT42PYXzP2MRZPRmcd70/u5IX3LsV5Pi6XVqsFjjmIYnvKOa9rw
-XICiCVdv5374CLwlTh4AnsstIjKpGOfWNx2cPXEDHtUQUXW+aaoNTR8gZOEs68qr
-EpKz87xbl4pLo33nOFOSs0JU24nRGfLwOF3vN/usPqFEUyqquSWSOWfm3XPgKZlm
-JrpmI/MgJ6YZunEujdvogT479RZ/IGq/Z/MhZaJj4iOcdq0iZqPUaKtV7v1lrl8S
-1Z2O5fiVdoc/95n1D2ZQW7M5/+d9RiGuGSfVD95VA5WmQdGhRlV+MdeoGvvC+/F3
-1pMl61YBvGc7jpPM6GA535Cmb9yXZFiKsutTHuDWEMngjfvlFV2qrxNy9PX+AQ+W
-XbidvCZKQqxE6fgnFIQxsI82ZCkdddI9d9ifMt4qkFNeJDbyeNxPuea0qb4752er
-5wIDAQABo1MwUTAdBgNVHQ4EFgQUYB+DRN17B+CMNJCRMRlvrR26HbAwHwYDVR0j
-BBgwFoAUYB+DRN17B+CMNJCRMRlvrR26HbAwDwYDVR0TAQH/BAUwAwEB/zANBgkq
-hkiG9w0BAQsFAAOCAgEAuWn+Vea4esUk5HCZH5KVd43jhoN5qZ0EOVB0jNQ+JayW
-/n3FO+o6N+CTqT1gU11uUp1H54N24s6oj+a/VuFzy38Delu34qKA8Y+rSnM/IgxW
-Uo6M1exgPQ0KqSZvbiJ0JamdIaO14OL5hS7ZzNWo3ZnvDaG04tfOAUPPAIqRt1cq
-ilRemHc4WmJ/U/7Vf1HaJ+QWEMQUVg0WbDHfsVP2EY+L1oQD7ZEoPKkCLcd/pGeP
-1eoGxV6vKJL7JD8Sdl1UoHPksp/1+LIB4s6JE68NrksY3TqF5vC8jKHiG67h0XJ8
-WoWriNK/T6tSLj/ApAL1qeyz1nG1iccGJ4gaBOFH0kDl1vkU2qTbMQJv59cLUHWv
-boevsBp356BiCBMYYkTvLAS4LDA27tvFcuzHtnaxQi22BnwZap9dvQJuxxtvfgCj
-zeqmrCxwuuQpPvhHO4DJQxMxxeado6IyQmuVU6VJAnobBI2KIiGRDjldRqGe+aFe
-6sTqW+NTs5ehkf0O12JTE9V2/yxALBd8BWEFhfaZfjU4g22TSF+1oPgd2r8qvmg6
-fICwA9tna6N36NyDnic1V+xF+93wBxIfhl+ZtzMISzxYlh+zyfipvz4qJb0Hhk0S
-u8FUK+ksijxQTFP/ZFXNw/r8ufC1mHsWbD0bCqRhb3eVblU1f9e2XLmW4LUgtII=
------END CERTIFICATE-----`)
-
-var caKey = []byte(`-----BEGIN RSA PRIVATE KEY-----
-MIIJKAIBAAKCAgEAx4kOyWzgr5hMPlWEGPuIi8LUx3vRsh9812Lo3nqgua3AVOTA
-Q/DcqgY0g4vyT1xIgqQZGM5g7ZqoghJrqIvK+iwA6CVHaNkFM7vkvVFbexaoF0Tc
-2QuRJ4dRfZv6ZMs+/hrbkAeDyEBn++BTZc2uQXfvTZiaw2CsY+snV6F00oU0KzBM
-d1svD86qScNdNOv0qPDYeI3ruNQya+N23DtidPfzKTnfacwdhog4Kx7uTORAFCTj
-VrretqFk+Nj2F8z9jEWT0ZnHe9P7uSF9y7FeT4ul1arBY45iGJ7yjmva8FyAoglX
-b+d++Ai8JU4eAJ7LLSIyqRjn1jcdnD1xAx7VEFF1vmmqDU0fIGThLOvKqxKSs/O8
-W5eKS6N95zhTkrNCVNuJ0Rny8Dhd7zf7rD6hRFMqqrklkjln5t1z4CmZZia6ZiPz
-ICemGbpxLo3b6IE+O/UWfyBqv2fzIWWiY+IjnHatImaj1GirVe79Za5fEtWdjuX4
-lXaHP/eZ9Q9mUFuzOf/nfUYhrhkn1Q/eVQOVpkHRoUZVfjHXqBr7wvvxd9aTJetW
-AbxnO46TzOhgOd+Qpm/cl2RYirLrUx7g1hDJ4I375RVdqq8TcvT1/gEPll24nbwm
-SkKsROn4JxSEMbCPNmQpHXXSPXfYnzLeKpBTXiQ28njcT7nmtKm+O+dnq+cCAwEA
-AQKCAgBvQnYzTHmQj+xbiZWJ1J+TxsScoucPWk1jUCym+VurjT3EWHT4rVJtn94i
-R6OKKtvntJal5VXYxzcUqC7NoX1Bt82dpEPIK9KhwTBPfBD1dnGt3+EBSVjb4LFI
-x/N7xnTOfa1WB0qtG3Sf1rrJ9kEnEjgmXWRWcw5M/K9IRqf8RvgK6PiKSRbZypPb
-Y4sSWktm9DzQI9p/ihq/W+tH6/j/Xc6Be1qfBIimHkiriqi3yUINuW/mSXasARxr
-QZcfOFdcouNEqWm5Gz+uQAWD0dfTpPuIQ5ln6Nm7/s0jKvK+ueWj9G+D32JF7aDz
-cDZ8hA6okPwMm+2R3dOt7fiZE9UbMWf/2m51r2/T3hdYGzQoAp7i85delBgp8HOH
-vJVTy0OC2wvxfVAPdmJU5L6zZQ8cz996W97o2KKMDLvQ4L4ttPUVBpS+CgmA8WU7
-xptSFJcUL72Dp//WoGvhQxL8ZEeYEYMnO+s3Dd2HurLjibdERrgEzRr39J1/n5TU
-gNtTwGNmFCv3pqKt/S44/iCUhEsb/tBZwSzozGNxJg6hBaNMw7L6ZCvW6Y6Yjxd5
-EYWKS9fbtVnDkIMBMlGwPgewacs9pD7sCRN5BJJTiHqhQC9KPeSOsA1X4sJHoxff
-ZLmkZ2hOHk00ZRO6z9PSKnVwf/2JUuweUfKOYPq1UiAmnSj74QKCAQEA/qxfWloV
-AaNeoD9XtgEx7qUsQJUBdWnEwiWI+N56VeXfhrv+tNBGpFnUcAQegJfBltAKTUgm
-P+t5SRDxEYWP7PWElDkUsZYm3590VOpapKR/zSE+3QKKbTnHIYSp0G0FAMSFStXK
-/cCjk3j0XIcESmS8nKVPXmjdhaWJ/dXn5AnEDVw0uTiA3++rrT5tA282134P/5YB
-erlcnSeHqtvfyb3y75DvVK+0vM9fmlo5Nkn3yaz5OOsDINZ7O7fToyimHxw6jgSU
-gzhnSL8+a/Bm/eRDDHPu/2D3dkCIfeyzUUKk2uVvzOZXYL0PdxPBxAK4KU8c/nsB
-JdrchNiTBMGnlwKCAQEAyJMnhILkRFr0jRdsxOKpzT5Bv0HC7K1kY1zrnfJHo+r5
-7Sq11s1J4z/C08RbXivL1nJ/5ILF9nMu3WtO5YhltAeStBf4LT5v2ofhv4897iJQ
-kVYFf38N6H/Te0vY8LmGRLqW9t51Lo3D6yVLBEYnihP4GdgPxRgOlRdFDWBDLCRn
-LQvVpl+SQcywna0w6gXGGCEN4rLV5H2tYdKkEwVWp4A3KF1nnA7bD+QwRDDHc7t+
-gZt11JICS/jC9QDoPtmQIJdFFwFOxmZ+yZ1UvJuT6IAKJb7I2vfH5ciKjjS8qhH8
-O1yOi/P9qOEqAzT5+6L1zAPanpz2iYChR1UjofEoMQKCAQAaeZbsEKNQaUhkBlG6
-9QLY2UjxacweBaHTwQ0tOgujtGL5Yb/H0kMVwNTp1DPLkHsqj3QStqZrTLJuGxnE
-hYsBykA/HHP/RinCY5Q3Y6mKpiM3EvazCRmU40XFQUJaDYtQmh11OyaAHK+knBVj
-LRIQHcrRygmnOeWViDEBN2SE+1LrRKOigbI8FXFWcD/q9HvSCSPmoRSESpLLL5nV
-9EeedGW16+5FcoKqgjBhHnIGJ8hfqeC6vwuzNTjYa3LP6mDiqQ+ZRfaecZWjJWZ6
-2CIM0Nb7i23UFKOFIo5N8PZvQytaKjHmLif1QZJDAcXJ97JncPcFqYnkAo2cLduS
-ygL/AoIBAQCUAgryPMiHLHsztmp8KyrUGrHXmYZmsljW/dWcmxGEgzvkaFUA6kIw
-4Hc7X7Vwm27yk1GO5XWBtGOL3si8llc+bywxm1J2yJEvuH+8pM41cLr1VH4AJFi2
-DcWYQVMX6D+NbgdCqsvcC57cYYum3sIEoVG+eHLCpUr1d9Nr2HIZG8/LLOV+vR2n
-Uo2t/QSQXKxeV93wQLmXv6n2+sI6iwDz36hUMADp5wh+BIwddcVowJ3MtFRSBWCO
-gUYUF5RJ9K/nbNj97egcfbvnuSKzfza5JerXCZ8b/iZTiRW9dGsYMOdpQpap7eVr
-/qPK9AfYSduJrfpge0FuHC5m/guqT9OxAoIBAGWDwuTcByslv+QV5EJiMoaD/tRf
-yLC4ZjI2qoCzbL8zpy11s01Ft+16GnM8POxic3tYglc+HI3TA6ec5CGd8k58TMfj
-XCw8Utu9j6ikeYWoxvtXQTpJGD4gFqz5eGMzlhfc+aLTnbqgDjKcwCCQl9tDFDvc
-rpOm838ZvTrzg+KjS8cNwAtAsitL9xO3VO8d0y323r8wUEIs8h3xZvXJS1Yqkrim
-LE+I5gU7HGa56SA8mQ4uMWx5YuAxzl3rDWI2liGbQSHuhK73u+5UxJsj/fOGOeuU
-Qo5Wsj2uyWBPVhAW7rYRPefEjPZUDAtPbWsja1E1lj+7bXfyMjMoLPaWsZk=
------END RSA PRIVATE KEY-----`)
+func getCA() ([]byte, []byte, error) {
+	if fileExists("rootCA.crt") && fileExists("rootCA.key") {
+		caCert, err := ioutil.ReadFile("rootCA.crt")
+		if err != nil {
+			return nil, nil, err
+		}
+		caKey, err := ioutil.ReadFile("rootCA.key")
+		if err != nil {
+			return nil, nil, err
+		}
+		return caCert, caKey, err
+	}
+
+	// files do not exist, make new ones instead
+	// source: https://golang.org/src/crypto/tls/generate_cert.go
+	priv, err := rsa.GenerateKey(rand.Reader, 2048)
+	panicOnErr(err)
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	notBefore := time.Now()
+	notAfter := notBefore.Add(3 * 365 * 24 * time.Hour) // 3 years
+	panicOnErr(err)
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"github.com/coolspring8/rwppa"},
+		},
+		NotBefore: notBefore,
+		NotAfter:  notAfter,
+
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+		IsCA:                  true,
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
+	panicOnErr(err)
+	certOut, err := os.Create("rootCA.crt")
+	panicOnErr(err)
+	err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+	panicOnErr(err)
+	err = certOut.Close()
+	panicOnErr(err)
+
+	keyOut, err := os.OpenFile("rootCA.key", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	panicOnErr(err)
+	privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
+	panicOnErr(err)
+	err = pem.Encode(keyOut, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes})
+	panicOnErr(err)
+	err = keyOut.Close()
+	panicOnErr(err)
+
+	caCert, err := ioutil.ReadFile("rootCA.crt")
+	if err != nil {
+		return nil, nil, err
+	}
+	caKey, err := ioutil.ReadFile("rootCA.key")
+	if err != nil {
+		return nil, nil, err
+	}
+	return caCert, caKey, err
+}
 
 func setCA(caCert, caKey []byte) error {
 	goproxyCa, err := tls.X509KeyPair(caCert, caKey)
@@ -136,3 +125,17 @@ func setCA(caCert, caKey []byte) error {
 	goproxy.RejectConnect = &goproxy.ConnectAction{Action: goproxy.ConnectReject, TLSConfig: goproxy.TLSConfigFromCA(&goproxyCa)}
 	return nil
 }
+
+func fileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}
+
+func panicOnErr(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
diff --git a/proxy.go b/proxy.go
index b5be89b..de9625e 100644
--- a/proxy.go
+++ b/proxy.go
@@ -56,7 +56,14 @@ type reqData struct {
 }
 
 func startProxyServer(listenAddr string, twfid string) {
-	setCA(caCert, caKey)
+	caCert, caKey, err := getCA()
+	if err != nil {
+		panic(err)
+	}
+	err = setCA(caCert, caKey)
+	if err != nil {
+		panic(err)
+	}
 
 	proxy := goproxy.NewProxyHttpServer()
 	proxy.Verbose = true