前端登录验证

随着技术发展，前端登录验证也是层出不穷，今天主要介绍一下主流的滑块认证和验证码认证

1. 滑块认证
   滑块认证属于行为认证，主要通过用户的操作行为来区分机器模拟行为。实现如下，这里使用vue搭建的系统。
   系统界面：

	<!-- 先在页面上设置两个容器，用于存放滑块图片和验证结果 -->
      <div ref="captcha" id="captcha"></div>
      <div id="msg"></div>
      <script>
      // 引入js文件
      import '@/utils/slideBlock.js'
			data() {
				return {
				  slideRules: false, //滑块验证
				}
			  },
			mounted() {
				this.getCaptcha()
			  },
			methods: {
				getCaptcha() {
				  jigsaw.init({
					el: this.$refs.captcha,
					onSuccess: this.onSuccess,
					onFail: this.onFail,
					onRefresh: this.cleanMsg
				  })
				},
				onSuccess() {
				  this.slideRules = true
				  this.$message.success('验证成功')
				  // 后台登录认证
				},
				onFail() {
				  this.slideRules = false
				  this.$message.error('验证失败，重新滑动')
				},
				cleanMsg() {
				  this.slideRules = false
				},
			}

到这里界面部分就结束了，接下来只要引入对应的js和css文件就可以了（css文件在js中引入）
**js页面：**

const l = 42, // 滑块边长
  r = 9, // 滑块半径
  w = 310, // canvas宽度
  h = 155, // canvas高度
  PI = Math.PI
const L = l + r * 2 + 3 // 滑块实际边长
const isIE = window.navigator.userAgent.indexOf('Trident') > -1

function getRandomNumberByRange (start, end) {
  return Math.round(Math.random() * (end - start) + start)
}

function createCanvas (width, height) {
  const canvas = document.createElement('canvas')
  canvas.width = width
  canvas.height = height
  return canvas
}

function createImg (onload) {
  const img = new Image()
  img.crossOrigin = "Anonymous"
  img.onload = onload
  img.onerror = () => {
   img.setSrc(getRandomImgSrc())
  }
  
  img.setSrc = function (src) {
    if (isIE) { // IE浏览器无法通过img.crossOrigin跨域，使用ajax获取图片blob然后转为dataURL显示
      const xhr = new XMLHttpRequest()
      xhr.onloadend = function (e) {
        const file = new FileReader() // FileReader仅支持IE10+
        file.readAsDataURL(e.target.response)
        file.onloadend = function (e) {
          img.src = e.target.result
        }
      }
      xhr.open('GET', src)
      xhr.responseType = 'blob'
      xhr.send()
    }
    else img.src = src
  }
  // 设置随机图像
  img.setSrc(getRandomImgSrc())
  return img
}

function createElement (tagName, className) {
  const elment = document.createElement(tagName)
  elment.className = className
  return elment
}

function addClass (tag, className) {
  tag.classList.add(className)
}

function removeClass (tag, className) {
  tag.classList.remove(className)
}
// 随机图片地址
function getRandomImgSrc () {
  return '//picsum.photos/300/150/?image=' + getRandomNumberByRange(0, 1084)
}

function draw (ctx, x, y, operation) {
  ctx.beginPath()
  ctx.moveTo(x, y)
  ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
  ctx.lineTo(x + l, y)
  ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
  ctx.lineTo(x + l, y + l)
  ctx.lineTo(x, y + l)
  ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
  ctx.lineTo(x, y)
  ctx.lineWidth = 2
  ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
  ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
  ctx.stroke()
  ctx[operation]()
  ctx.globalCompositeOperation = 'destination-over'
}

function sum (x, y) {
  return x + y
}

function square (x) {
  return x * x
}

import  './slideBlock.css'

class jigsaw {
  constructor ({ el, onSuccess, onFail, onRefresh }) {
    el.style.position = 'relative'
    el.style.width = w + 'px'
    Object.assign(el.style, {
      position: 'relative',
      width: w + 'px',
      margin: '0 auto'
    })
    this.el = el
    this.onSuccess = onSuccess
    this.onFail = onFail
    this.onRefresh = onRefresh
  }

  init () {
    this.initDOM()
    this.initImg()
    this.bindEvents()
  }

  initDOM () {
    const canvas = createCanvas(w, h) // 画布
    const block = canvas.cloneNode(true) // 滑块
    const sliderContainer = createElement('div', 'sliderContainer')
    const refreshIcon = createElement('div', 'refreshIcon')
    const sliderMask = createElement('div', 'sliderMask')
    const slider = createElement('div', 'slider')
    const sliderIcon = createElement('span', 'sliderIcon')
    const text = createElement('span', 'sliderText')

    block.className = 'block'
    text.innerHTML = '向右滑动填充拼图'

    const el = this.el
    el.appendChild(canvas)
    el.appendChild(refreshIcon)
    el.appendChild(block)
    slider.appendChild(sliderIcon)
    sliderMask.appendChild(slider)
    sliderContainer.appendChild(sliderMask)
    sliderContainer.appendChild(text)
    el.appendChild(sliderContainer)

    Object.assign(this, {
      canvas,
      block,
      sliderContainer,
      refreshIcon,
      slider,
      sliderMask,
      sliderIcon,
      text,
      canvasCtx: canvas.getContext('2d'),
      blockCtx: block.getContext('2d')
    })
  }

  initImg () {
    const img = createImg(() => {
      this.draw()
      this.canvasCtx.drawImage(img, 0, 0, w, h)
      this.blockCtx.drawImage(img, 0, 0, w, h)
      const y = this.y - r * 2 - 1
      const ImageData = this.blockCtx.getImageData(this.x - 3, y, L, L)
      this.block.width = L
      this.blockCtx.putImageData(ImageData, 0, y)
    })
    this.img = img
  }

  draw () {
    // 随机创建滑块的位置
    this.x = getRandomNumberByRange(L + 10, w - (L + 10))
    this.y = getRandomNumberByRange(10 + r * 2, h - (L + 10))
    draw(this.canvasCtx, this.x, this.y, 'fill')
    // 绘制滑块
    draw(this.blockCtx, this.x, this.y, 'clip')
  }

  clean () {
    this.canvasCtx.clearRect(0, 0, w, h)
    this.blockCtx.clearRect(0, 0, w, h)
    this.block.width = w
  }

  bindEvents () {
    this.el.onselectstart = () => false
    this.refreshIcon.onclick = () => {
      this.reset()
      typeof this.onRefresh === 'function' && this.onRefresh()
    }

    let originX, originY, trail = [], isMouseDown = false

    const handleDragStart = function (e) {
      originX = e.clientX || e.touches[0].clientX
      originY = e.clientY || e.touches[0].clientY
      isMouseDown = true
    }

    const handleDragMove = (e) => {
      if (!isMouseDown) return false
      const eventX = e.clientX || e.touches[0].clientX
      const eventY = e.clientY || e.touches[0].clientY
      const moveX = eventX - originX
      const moveY = eventY - originY
      if (moveX < 0 || moveX + 38 >= w) return false
      this.slider.style.left = moveX + 'px'
      const blockLeft = (w - 40 - 20) / (w - 40) * moveX
      this.block.style.left = blockLeft + 'px'

      addClass(this.sliderContainer, 'sliderContainer_active')
      this.sliderMask.style.width = moveX + 'px'
      trail.push(moveY)
    }

    const handleDragEnd = (e) => {
      if (!isMouseDown) return false
      isMouseDown = false
      const eventX = e.clientX || e.changedTouches[0].clientX
      if (eventX == originX) return false
      removeClass(this.sliderContainer, 'sliderContainer_active')
      this.trail = trail
      const { spliced, verified } = this.verify()
      if (spliced) {
        if (verified) {
          addClass(this.sliderContainer, 'sliderContainer_success')
          typeof this.onSuccess === 'function' && this.onSuccess()
        } else {
          addClass(this.sliderContainer, 'sliderContainer_fail')
          this.text.innerHTML = '再试一次'
          this.reset()
        }
      } else {
        addClass(this.sliderContainer, 'sliderContainer_fail')
        typeof this.onFail === 'function' && this.onFail()
        setTimeout(() => {
          this.reset()
        }, 1000)
      }
    }
    this.slider.addEventListener('mousedown', handleDragStart)
    this.slider.addEventListener('touchstart', handleDragStart)
    this.block.addEventListener('mousedown', handleDragStart)
    this.block.addEventListener('touchstart', handleDragStart)
    document.addEventListener('mousemove', handleDragMove)
    document.addEventListener('touchmove', handleDragMove)
    document.addEventListener('mouseup', handleDragEnd)
    document.addEventListener('touchend', handleDragEnd)
  }
  /**
   * 进行验证
   */
  verify () {
    const arr = this.trail // 拖动时y轴的移动距离
    console.log(this.trail)
    // 求平均数
    const average = arr.reduce(sum) / arr.length
    // 计算偏差
    const deviations = arr.map(x => x - average)
    // 
    const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length)
    console.log(stddev);
    // 计算滑块左边距离
    const left = parseInt(this.block.style.left)
    return {
      // 如果偏差小于10
      spliced: Math.abs(left - this.x) < 10,
      verified: stddev !== 0, // 简单验证下拖动轨迹，为零时表示Y轴上下没有波动，可能非人为操作
    }
  }

  reset () {
    this.sliderContainer.className = 'sliderContainer'
    this.slider.style.left = 0
    this.block.style.left = 0
    this.sliderMask.style.width = 0
    this.clean()
    this.img.setSrc(getRandomImgSrc())
  }
}
/**
 * 设置window对象
 */
window.jigsaw = {
  init: function (opts) {
    return new jigsaw(opts).init()
  }
}

css文件：

.block {
    position: absolute;
    left: 0;
    top: 0;
    cursor: pointer;
    cursor: grab;
  }
  
  .block:active {
    cursor: pointer;
    cursor: grabbing;
  }
  
  .sliderContainer {
    position: relative;
    text-align: center;
    width: 310px;
    height: 40px;
    line-height: 40px;
    margin-top: 15px;
    background: #f7f9fa;
    color: #45494c;
    border: 1px solid #e4e7eb;
  }
  
  .sliderContainer_active .slider {
    height: 38px;
    top: -1px;
    border: 1px solid #1991FA;
  }
  
  .sliderContainer_active .sliderMask {
    height: 38px;
    border-width: 1px;
  }
  
  .sliderContainer_success .slider {
    height: 38px;
    top: -1px;
    border: 1px solid #52CCBA;
    background-color: #52CCBA !important;
  }
  
  .sliderContainer_success .sliderMask {
    height: 38px;
    border: 1px solid #52CCBA;
    background-color: #D2F4EF;
  }
  
  .sliderContainer_success .sliderIcon {
    background-position: 0 0 !important;
  }
  
  .sliderContainer_fail .slider {
    height: 38px;
    top: -1px;
    border: 1px solid #f57a7a;
    background-color: #f57a7a !important;
  }
  
  .sliderContainer_fail .sliderMask {
    height: 38px;
    border: 1px solid #f57a7a;
    background-color: #fce1e1;
  }
  
  .sliderContainer_fail .sliderIcon {
    top: 14px;
    background-position: 0 -82px !important;
  }
  .sliderContainer_active .sliderText, .sliderContainer_success .sliderText, .sliderContainer_fail .sliderText {
    display: none;
  }
  
  .sliderMask {
    position: absolute;
    left: 0;
    top: 0;
    height: 40px;
    border: 0 solid #1991FA;
    background: #D1E9FE;
  }
  
  .slider {
    position: absolute;
    top: 0;
    left: 0;
    width: 40px;
    height: 40px;
    background: #fff;
    box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
    transition: background .2s linear;
    cursor: pointer;
    cursor: grab;
  }
  
  .slider:active {
    cursor: grabbing;
  }
  
  .slider:hover {
    background: #1991FA;
  }
  
  .slider:hover .sliderIcon {
    background-position: 0 -13px;
  }
  
  .sliderIcon {
    position: absolute;
    top: 15px;
    left: 13px;
    width: 14px;
    height: 12px;
    background: url(http://cstaticdun.126.net//2.6.3/images/icon_light.f13cff3.png) 0 -26px;
    background-size: 34px 471px;
  }
  
  .refreshIcon {
    position: absolute;
    right: 0;
    top: 0;
    width: 34px;
    height: 34px;
    cursor: pointer;
    background: url(http://cstaticdun.126.net//2.6.3/images/icon_light.f13cff3.png) 0 -437px;
    background-size: 34px 471px;
  }

到这里，滑块就生成啦，接下来根据滑块对应的响应事件，完成自己的业务逻辑就可以啦
使用滑块验证虽然酷炫，但由于只在前端做的验证，没办法保证对服务器接口发起的登录攻击，所以传统的验证码登录还是有一定的用武之地的，接下来就看一下验证码怎么验证呢？

2.验证码验证
界面： 这里使用vue框架和antdv组件

<!-- 验证码验证 -->
      <a-form-item prop="code">
            <a-row :span="24">
                <a-col :span="16">
                    <a-input size="large"
                              pressEnter="handleSubmit"
                              v-model="loginForm.code"
                              placeholder="请输入验证码"
                              auto-complete="off"
                              v-decorator="[
                                'code',
                                {rules: [{ required: true, message: '请输入密码' }], validateTrigger: 'blur'}
                              ]"
                              >
                        <a-icon slot="prefix" type="safety-certificate" :style="{ color: 'rgba(0,0,0,.25)' }" />
                    </a-input>
                </a-col>
                <a-col :span="7" :offset="1">
                    <div>
                        <img :src="loginForm.image" style="height:100%;width:100%"  @click="getCaptchaCode"
                        />
                    </div>
                </a-col>
            </a-row>
        </a-form-item>
<script>
   export default {
   data() {
    return {
      form: this.$form.createForm(this),
      loginBtn: false,
      isLoginError: false,
      slideRules: false, //滑块验证
      loginForm: {
        //验证码的值
        code: "",
        key:"",
        //预加载白色背景
        image: "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7",
    },
    }
  },
  mounted() {
    this.getCaptchaCode()  //获取验证码
  },
  methods: {
  // 和后端请求验证码图片
    getCaptchaCode(){
      var that = this
      api.getCaptchaCode().then(res =>{
        that.loginForm.image = res.image
        that.loginForm.key = res.key
      })
    },
    }
   </script>

使用验证码登录，逻辑很简单，就是先向后端发请求获取验证码图片和对应的索引key，用户输入验证码值后，点击提交一并把账号密码和验证码发给后端，供后端验证。
验证方式层出不穷，主要理解验证逻辑，希望能帮助到大家，这里只有部分关键代码用做参考