HTML与Python生成验证码的对比分析

前言

验证码（CAPTCHA）是确保用户行为为人类而非机器人自动执行的一种安全机制。通过图形、文字、或其他手段生成复杂的验证码来防止自动化攻击是一种常见的方法。本文将对比分析使用HTML与JavaScript和Python生成验证码的两种方式，探讨各自的优劣之处。

HTML与JavaScript生成验证码

以下是用HTML与JavaScript生成验证码的代码示例：

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head><meta charset="UTF-8"><script src="https://cdn.staticfile.net/jquery/2.2.4/jquery.min.js"></script><title>验证码示例</title><style>#v_container {width: 200px;height: 50px;cursor: pointer;}#verifyCanvas {display: block;}</style>
</head>
<body><div id="v_container"></div><input type="text" id="code_input" placeholder="请输入验证码"/><button id="my_button">验证</button><script>(function(window, document) {function GVerify(options) {this.options = {id: options.id || "",canvasId: "verifyCanvas",width: options.width || "100",height: options.height || "30",type: options.type || "blend",code: "",numArr: "0,1,2,3,4,5,6,7,8,9".split(","),letterArr: getAllLetter()};this._init();this.refresh();}GVerify.prototype = {_init: function() {var con = document.getElementById(this.options.id);var canvas = document.createElement("canvas");this.options.width = con.offsetWidth || 100;this.options.height = con.offsetHeight || 30;canvas.id = this.options.canvasId;canvas.width = this.options.width;canvas.height = this.options.height;con.appendChild(canvas);var parent = this;canvas.onclick = function() {parent.refresh();}},refresh: function() {this.options.code = "";var canvas = document.getElementById(this.options.canvasId);var ctx = canvas.getContext('2d');ctx.textBaseline = "middle";ctx.fillStyle = randomColor(180, 240);ctx.fillRect(0, 0, this.options.width, this.options.height);var txtArr = this.options.type === "blend" ? this.options.numArr.concat(this.options.letterArr): this.options.type === "number" ? this.options.numArr: this.options.letterArr;for (var i = 1; i <= 4; i++) {var txt = txtArr[randomNum(0, txtArr.length)];this.options.code += txt;ctx.font = randomNum(this.options.height / 2, this.options.height) + 'px SimHei';ctx.fillStyle = randomColor(50, 160);ctx.shadowOffsetX = randomNum(-3, 3);ctx.shadowOffsetY = randomNum(-3, 3);ctx.shadowBlur = randomNum(-3, 3);ctx.shadowColor = "rgba(0, 0, 0, 0.3)";var x = this.options.width / 5 * i;var y = this.options.height / 2;var deg = randomNum(-30, 30);ctx.translate(x, y);ctx.rotate(deg * Math.PI / 180);ctx.fillText(txt, 0, 0);ctx.rotate(-deg * Math.PI / 180);ctx.translate(-x, -y);}for (var i = 0; i < 4; i++) {ctx.strokeStyle = randomColor(40, 180);ctx.beginPath();ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height));ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height));ctx.stroke();}for (var i = 0; i < this.options.width / 4; i++) {ctx.fillStyle = randomColor(0, 255);ctx.beginPath();ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI);ctx.fill();}},validate: function(code) {return code.toLowerCase() === this.options.code.toLowerCase();}}function getAllLetter() {var letterStr = "a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";return letterStr.split(",");}function randomNum(min, max) {return Math.floor(Math.random() * (max - min) + min);}function randomColor(min, max) {var r = randomNum(min, max);var g = randomNum(min, max);var b = randomNum(min, max);return "rgb(" + r + "," + g + "," + b + ")";}window.GVerify = GVerify;})(window, document);var verifyCode = new GVerify({id: "v_container", width: 200, height: 50});document.getElementById("my_button").onclick = function() {var res = verifyCode.validate(document.getElementById("code_input").value);alert(res ? "验证正确" : "验证码错误");}</script>
</body>
</html>

Python生成验证码

以下是用Python生成验证码的代码示例：

import random
from PIL import Image, ImageDraw, ImageFont
import stringdef create_CAPTCHA_content(length=4):characters = string.ascii_letters + string.digitsreturn ''.join(random.choice(characters) for _ in range(length))def generate_random_color():return (random.randint(0, 255), random.randint(0, 255), random.randint(0, 255))image = Image.new("RGB", (300, 100), generate_random_color())
draw = ImageDraw.Draw(image)
font = ImageFont.truetype(r'C:\Windows\Fonts\simhei.ttf', size=30)CAPTCHA_text = create_CAPTCHA_content()for i, char in enumerate(CAPTCHA_text):color = generate_random_color()position = (50 + i * 60, random.randint(15, 50))draw.text(position, text=char, font=font, fill=color)for _ in range(random.randint(7, 15)):start_point = (random.randint(0, 300), random.randint(0, 100))end_point = (random.randint(0, 300), random.randint(0, 100))draw.line([start_point, end_point], fill=generate_random_color(), width=2)print(CAPTCHA_text)
image.show()
image.save("CAPTCHA.png")