我正在尝试更快地加载验证码，然后在 WebBrowser 控件中呈现它们，然后复制/粘贴图像并将其呈现到图片框中。

为什么不直接将图片直接下载到 PictureBox 中，它的优点是使用更少的 CPU 使用率和内存几乎这个解决方案适用于任何其他更高级的验证码服务，称为 Solve Media(如果您查看，请使用 Solve Media下次您尝试查看图像 url 时，它会给您一个虚假的错误 catpcha 图像)。

但现在我还需要对 ReCaptcha 验证码系统的支持，以便以更快的速度自动化我的机器人，然后只需刷新网页并等待它呈现。

因此，据我所知，我将在这里编写我的代码 我只是缺少模拟 HTML 请求中的一个属性 我将 User-Agent 伪造为真正的 Internet Explorer 8，我认为问题在于Cookie 似乎以某种方式生成了一个我不知道在哪里的 cookie，但我也从下载 Javascript 文件中得到了一个 Cookie。

无论哪种方式，Google ReCaptcha 都试图用一个您无法阅读的假验证码来欺骗您，并在您的脸上摩擦它，表明您没有做正确的事情。我发现当您看到 2 个黑色圆圈时，很明显它是假的。

这是错误验证码和良好验证码的示例

有一次我记得 ReCaptcha 有另一个安全功能，如果你从它所在的实际域加载验证码图像，我不知道它是如何工作的，因为我在本地下载了所有内容，对吗？但他们似乎已经删除了该功能。 (实际上它存在于某些网站上似乎默认禁用，很容易欺骗它使用 Referer header )

我不想在这里作弊，我仍然会手动输入这些验证码，但我想输入它们的速度比正常渲染页面所需的速度更快。

我希望验证码变成那些街道号码……或者至少 2 个没有黑圈的单词。

无论如何，这是我的当前代码。

Dim newCaptcha = New Captcha
Dim myUserAgent As String = ""
Dim myReferer As String = "http://www.google.com/recaptcha/demo/"
Dim outputSite As String = HTTP.HTTPGET("http://www.google.com/recaptcha/demo/", "", "", "", myUserAgent, myReferer)
Dim recaptchaChallengeKey = GetBetween(outputSite, "http://www.google.com/recaptcha/api/challenge?k=", """")

'Google ReCaptcha Captcha
outputSite = HTTP.HTTPGET("http://www.google.com/recaptcha/api/challenge?k=" & recaptchaChallengeKey, "", "", "", myUserAgent, myReferer)

'outputSite = outputSite.Replace("var RecaptchaState = {", "{""RecaptchaState"": {")
'outputSite = outputSite.Replace("};", "}}")
'Dim jsonDictionary As Dictionary(Of String, Object) = New JavaScriptSerializer().Deserialize(Of Dictionary(Of String, Object))(outputSite)
Dim recaptchaChallenge = GetBetween(outputSite, "challenge : '", "',")
outputSite = HTTP.HTTPGET("http://www.google.com/recaptcha/api/js/recaptcha.js", "", "", "", myUserAgent, myReferer) 'This page looks useless but it seems the javascript loads this anyways, maybe this why I get bad captchas?

If HTTP.LoadWebImageToPictureBox(newCaptcha.picCaptcha, "http://www.google.com/recaptcha/api/image?c=" & recaptchaChallenge, myUserAgent, myReferer) = False Then
    MessageBox.Show("Recaptcha Image loading failed!")
Else
    Dim newWork As New Work
    newWork.CaptchaForm = newCaptcha
    newWork.AccountId = 1234 'ID of Accounts.
    newWork.CaptchaHash = "recaptcha_challenge_field=" & recaptchaChallenge
    newWork.CaptchaType = "ReCaptcha"
    Works.Add(newWork)
    newCaptcha.Show()
End If

这是我使用的 HTTP 类。

Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Net
Imports System.IO
Public Class HTTP

    Public StoredCookies As New CookieContainer

    Public Function HTTPGET(ByVal url As String, ByVal proxyname As String, ByVal proxylogin As String, ByVal proxypassword As String, ByVal userAgent As String, ByVal referer As String) As String
        Dim resp As HttpWebResponse
        Dim req As HttpWebRequest = DirectCast(WebRequest.Create(url), HttpWebRequest)

        If userAgent = "" Then
            userAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"
        End If
        req.UserAgent = userAgent
        req.Referer = referer
        req.AllowAutoRedirect = True
        req.ReadWriteTimeout = 5000
        req.CookieContainer = StoredCookies
        req.Headers.Set("Accept-Language", "en-us")

        req.KeepAlive = True
        req.Method = "GET"

        Dim stream_in As StreamReader

        If proxyname <> "" Then
            Dim proxyIP As String = proxyname.Split(New Char() {":"})(0)
            Dim proxyPORT As Integer = CInt(proxyname.Split(New Char() {":"})(1))

            Dim proxy As New WebProxy(proxyIP, proxyPORT)
            'if proxylogin is an empty string then don't use proxy credentials (open proxy)
            If proxylogin <> "" Then
                proxy.Credentials = New NetworkCredential(proxylogin, proxypassword)
            End If
            req.Proxy = proxy
        End If

        Dim response As String = ""
        Try
            resp = DirectCast(req.GetResponse(), HttpWebResponse)
            StoredCookies.Add(resp.Cookies)
            stream_in = New StreamReader(resp.GetResponseStream())
            response = stream_in.ReadToEnd()
            stream_in.Close()
        Catch ex As Exception
        End Try
        Return response
    End Function


    Public Function LoadWebImageToPictureBox(ByVal pb As PictureBox, ByVal ImageURL As String, ByVal userAgent As String, ByVal referer As String) As Boolean
        Dim bAns As Boolean

        Try
            Dim resp As WebResponse
            Dim req As HttpWebRequest

            Dim sURL As String = Trim(ImageURL)

            If Not sURL.ToLower().StartsWith("http://") Then sURL = "http://" & sURL

            req = DirectCast(WebRequest.Create(sURL), HttpWebRequest)

            If userAgent = "" Then
                userAgent = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET4.0C; .NET4.0E; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)"
            End If
            req.UserAgent = userAgent
            req.Referer = referer
            req.AllowAutoRedirect = True
            req.ReadWriteTimeout = 5000
            req.CookieContainer = StoredCookies
            req.Headers.Set("Accept-Language", "en-us")

            req.KeepAlive = True
            req.Method = "GET"

            resp = req.GetResponse()
            If Not resp Is Nothing Then
                Dim remoteStream As Stream = resp.GetResponseStream()
                Dim objImage As New MemoryStream
                Dim bytesProcessed As Integer = 0
                Dim myBuffer As Byte()
                ReDim myBuffer(1024)
                Dim bytesRead As Integer
                bytesRead = remoteStream.Read(myBuffer, 0, 1024)
                Do While (bytesRead > 0)
                    objImage.Write(myBuffer, 0, bytesRead)
                    bytesProcessed += bytesRead
                    bytesRead = remoteStream.Read(myBuffer, 0, 1024)
                Loop
                pb.Image = Image.FromStream(objImage)
                bAns = True
                objImage.Close()
            End If
        Catch ex As Exception
            bAns = False
        End Try

        Return bAns
    End Function
End Class

编辑: 我发现问题出在这个 Google Javascript 客户端混淆加密系统上

http://www.google.com/js/th/1lOyLe_nzkTfeM2GpTkE65M1Lr8y0MC8hybXoEd-x1s.js

我仍然希望能够在不使用重型网络浏览器的情况下打败它，也许是一些轻量级的快速 javascript 评估控件？ 取消混淆并将其移植到 VB.NET 是没有意义的，因为一旦我这样做，它们可能会完全更改一些变量或加密，而我所做的所有工作都是徒劳的，所以我想要更智能的东西。在这一点上，我什至不知道 URL 是如何生成的，它现在看起来确实是静态的，它可能是一个真实的文件，而不仅仅是及时生成的文件。

结果是 _challenge 页面给出了图像的挑战只是一个诱饵挑战.. 然后这个挑战被替换(也许加密？)客户端使用变量 t1, t2, t3,似乎每次都没有使用这种加密，如果你一旦通过它就可以访问我正在尝试做的事情我的代码几乎可以工作但它会以非常随机的间隔停止工作，我想要更可靠的东西我可以无人看管周。

最佳答案

我遇到了同样的问题并找到了一个解决方案，它不会提供最简单的验证码，但至少会提供更容易的图像。结果将是一个可读的单词和一个模糊的单词。

我发现下载“recaptcha/api/reload”对于实现这一点很重要。 此外，添加“cachestop”参数和引用者可能会有所不同。

data = UrlMgr("http://www.google.com/recaptcha/api/challenge?k=%s&cachestop=%.17f" % (id, random.random()), referer=referer, nocache=True).data
challenge = re.search("challenge : '(.*?)',", data).group(1)
server = re.search("server : '(.*?)',", data).group(1)
# this step is super important to get readable captchas - normally we could take the "c" from above and already retrieve a captcha but
# this one would be barely readable
reloadParams["c"] = challenge
reloadParams["k"] = id
reloadParams["lang"] = "de"
reloadParams["reason"] = "i"
reloadParams["type"] = "image"
data = UrlMgr("http://www.google.com/recaptcha/api/reload" , params=reloadParams, referer=referer, nocache=True).data
challenge = textextract(data, "Recaptcha.finish_reload('", "',")
return challenge, solveCaptcha(UrlMgr("%simage" % (server), params={"c":challenge}, referer=referer))

为了进一步改进，我猜测“th”参数用于检测机器人。它是由我自己没有调试的一些复杂的 javascript 生成的。

关于javascript - 从 Google ReCaptcha 抓取中获取错误的验证码图像，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24904924/