Blogengine.NET – reCaptcha 0.93 Installation Instructions

by filip 25. February 2010 22:33

These installation instructions now apply to version 0.95

First, the linked ZIP file contains the updated files for installing the Recaptcha control.


  • Version 0.95 – Changed initial loading method to fix error that occurred in certain cases in IE. If upgrading from 0.94, you only need to replace the Recaptcha.cs file.
  • Version 0.94 – Logging fixes
  • Version 0.93 – Added logging.
  • Version 0.92 - The recaptcha will no longer get focus after it has been loaded. Install procedure is unchanged from version 0.91.
  • Version 0.91 - Changed the way that Recaptcha is verified.  It should no longer be possible to bypass the recaptcha by manually executing JavaScript on the page.
  • Version 0.9 - Initial Version


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Web Development

Blogengine.NET Recaptcha 0.91 Installation Instructions

by filip 20. February 2010 20:27

NOTE: THESE INSTALLATION INSTRUCTIONS HAVE BEEN UPDATED: To get the latest version, follow the instructions located at:

First, the linked ZIP file contains the updated files for installing the Recaptcha control.


  • Version 0.92 - The recaptcha will no longer get focus after it has been loaded. Install procedure is unchanged from version 0.91.
  • Version 0.91 - Changed the way that Recaptcha is verified.  It should no longer be possible to bypass the recaptcha by manually executing JavaScript on the page.
  • Version 0.9 - Initial Version

Quick Installation

First, back up your files in case you need to revert for any reason. If you have not modified any of the BlogEngine files, you can extract the ZIP linked to above and place all of the files into their proper locations ( the unzipped files should contain a folder structure ). There is no need to recompile.

You may need to force a refresh of your browser on the site, since there is a JavaScript file updated, and most browsers like to cache these files.

Manual Installation

Below is a complete summary of what needs to be altered to make the Recaptcha control work.  You’ll need to do this for any files manually modified in your BlogEngine.NET instance.


This file was not included in the BlogEngine.NET installation, and should be placed in the ‘/App_Code/Controls/’ folder.


There are three functions in this file that need to be updated to the following:

onCommentError: function(error, context) {
        error = error || "Unknown error occurred.";
        var iDelimiterPos = error.indexOf("|");
        if (iDelimiterPos > 0) {
            error = error.substr(0, iDelimiterPos);
            // Remove numbers from end of error message.
            while (error.length > 0 && error.substr(error.length - 1, 1).match(/\d/)) {
                error = error.substr(0, error.length - 1);
        if( document.getElementById('recaptcha_response_field') )
        alert("Sorry, the following error occurred while processing your comment:\n\n" + error);
addComment: function(preview) {
        var isPreview = preview == true;
        if (!isPreview) {
            this.$("status").innerHTML = BlogEngine.i18n.savingTheComment;
        var author = BlogEngine.comments.nameBox.value;
        var email = BlogEngine.comments.emailBox.value;
        var website = BlogEngine.comments.websiteBox.value;
        var country = BlogEngine.comments.countryDropDown ? BlogEngine.comments.countryDropDown.value : "";
        var content = BlogEngine.comments.contentBox.value;
        var notify = BlogEngine.$("cbNotify").checked;
        var captcha = BlogEngine.comments.captchaField.value;
        var replyToId = BlogEngine.comments.replyToId ? BlogEngine.comments.replyToId.value : "";
        var recaptchaResponseField = document.getElementById('recaptcha_response_field');        
        var recaptchaResponse = recaptchaResponseField ? recaptchaResponseField.value : "";
        var recaptchaChallengeField = document.getElementById('recaptcha_challenge_field');
        var recaptchaChallenge = recaptchaChallengeField ? recaptchaChallengeField.value : "";
        var avatarInput = BlogEngine.$("avatarImgSrc");
        var avatar = (avatarInput && avatarInput.value) ? avatarInput.value : "";
        var callback = isPreview ? BlogEngine.endShowPreview : BlogEngine.appendComment;
        var argument = author + "-|-" + email + "-|-" + website + "-|-" + country + "-|-" + content + "-|-" + notify + "-|-" + isPreview + "-|-" + captcha + "-|-" + replyToId + "-|-" + avatar + "-|-" + recaptchaResponse + "-|-" + recaptchaChallenge;
        WebForm_DoCallback(BlogEngine.comments.controlId, argument, callback, 'comment', BlogEngine.onCommentError, false);
        if (!isPreview && typeof (OnComment) != "undefined")
            OnComment(author, email, website, country, content);
appendComment: function(args, context) {
        if (context == "comment") {
            if( document.getElementById('recaptcha_response_field') )
            if( args == "RecaptchaIncorrect" )
               if( document.getElementById("spnCaptchaIncorrect") ) document.getElementById("spnCaptchaIncorrect").style.display = "";
                if( document.getElementById("spnCaptchaIncorrect") ) document.getElementById("spnCaptchaIncorrect").style.display = "none";
                var commentList = BlogEngine.$("commentlist");
                if (commentList.innerHTML.length < 10)
                    commentList.innerHTML = "<h1 id='comment'>" + BlogEngine.i18n.comments + "</h1>"
                // add comment html to the right place
                var id = BlogEngine.comments.replyToId ? BlogEngine.comments.replyToId.value : '';
                if (id != '') {
                    var replies = BlogEngine.$('replies_' + id);
                    replies.innerHTML += args;
                } else {
                    commentList.innerHTML += args;
           = 'block';
                // reset form values
                BlogEngine.comments.contentBox.value = "";
                BlogEngine.comments.contentBox = BlogEngine.$(;
                BlogEngine.$("status").className = "success";
                if (!BlogEngine.comments.moderation)
                    BlogEngine.$("status").innerHTML = BlogEngine.i18n.commentWasSaved;
                    BlogEngine.$("status").innerHTML = BlogEngine.i18n.commentWaitingModeration;
                // move form back to bottom
                var commentForm = BlogEngine.$('comment-form');
                // reset reply to
                if (BlogEngine.comments.replyToId) BlogEngine.comments.replyToId.value = '';
                if (BlogEngine.$('cancelReply')) BlogEngine.$('cancelReply').style.display = 'none';
        BlogEngine.$("btnSaveAjax").disabled = false;

/User controls/CommentView.ascx.cs

One method in this file needs to be updated:

/// <summary>
    /// Processes a callback event that targets a control.
    /// </summary>
    /// <param name="eventArgument">A string that represents an event argument to pass to the event handler.</param>
    public void RaiseCallbackEvent(string eventArgument)
        if (!BlogSettings.Instance.IsCommentsEnabled)
        string[] args = eventArgument.Split(new string[] { "-|-" }, StringSplitOptions.None);
        string author = args[0];
        string email = args[1];
        string website = args[2];
        string country = args[3];
        string content = args[4];
        bool notify = bool.Parse(args[5]);
        bool isPreview = bool.Parse(args[6]);
        string sentCaptcha = args[7];
        //If there is no "reply to" comment, args[8] is empty
        Guid replyToCommentID = String.IsNullOrEmpty(args[8]) ? Guid.Empty : new Guid(args[8]);
        string avatar = args[9];
        string recaptchaResponse = args[10];
        string recaptchaChallenge = args[11];
        if (!isPreview && recaptcha.RecaptchaEnabled && recaptcha.RecaptchaNecessary)
            if (!recaptcha.ValidateAsync(recaptchaResponse, recaptchaChallenge))
                _Callback = "RecaptchaIncorrect";
        string storedCaptcha = hfCaptcha.Value;
        if (sentCaptcha != storedCaptcha)
        Comment comment = new Comment();
        comment.Id = Guid.NewGuid();
        comment.ParentId = replyToCommentID;
        comment.Author = Server.HtmlEncode(author);
        comment.Email = email;
        comment.Content = Server.HtmlEncode(content);
        comment.IP = Request.UserHostAddress;
        comment.Country = country;
        comment.DateCreated = DateTime.Now;
        comment.Parent = Post;
        comment.IsApproved = !BlogSettings.Instance.EnableCommentsModeration;
        comment.Avatar = avatar.Trim();
        if (Page.User.Identity.IsAuthenticated)
            comment.IsApproved = true;
        if (website.Trim().Length > 0)
            if (!website.ToLowerInvariant().Contains("://"))
                website = "http://" + website;
            Uri url;
            if (Uri.TryCreate(website, UriKind.Absolute, out url))
                comment.Website = url;
        if (!isPreview)
            if (notify && !Post.NotificationEmails.Contains(email))
            else if (!notify && Post.NotificationEmails.Contains(email))
            SetCookie(author, email, website, country);
        string path = Utils.RelativeWebRoot + "themes/" + BlogSettings.Instance.Theme + "/CommentView.ascx";
        CommentViewBase control = (CommentViewBase)LoadControl(path);
        control.Comment = comment;
        control.Post = Post;
        using (StringWriter sw = new StringWriter())
            control.RenderControl(new HtmlTextWriter(sw));
            _Callback = sw.ToString();

/User controls/CommentView.ascx

Finally, the following line needs to be added to this file, at the location you would like the Recaptcha control to appear. Remember to update your TabIndexes for proper tab button navigation.

<blog:RecaptchaControl ID="recaptcha" runat="server" TabIndex="8" />

Recaptcha Settings

You can edit the Recaptcha settings via the Extension Manager. You probably should enter in your own Public and Private keys, as the provided keys are for this site ( they are global, so they will work on other sites ).

Recaptcha Theming

There are 4 built-in themes that you can change via the ExtensionManager. You can also create your own theme by adding it in the following way to the Recaptcha control:

<blog:RecaptchaControl ID="recaptcha" runat="server" TabIndex="8" Theme="MyCustomTheme" />

For detailed instructions on what your theme needs to look like, visit the Recaptcha site.

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Web Development

Async Recaptcha for BlogEngine.NET 1.6

by filip 20. February 2010 02:03

UPDATE: The latest installation instructions and files are available by following this link:

The instructions on this page are no longer valid for the latest version.

I really am getting sick of the spam that is appearing on this blog, so yesterday I decided to implement Recaptcha for BlogEngine.NET. I had three main goals:

  1. Easy to implement – as any control, it needs to be pretty trivial to add it to an existing blog instance
  2. Configurable via the Extensions panel – I really like what BlogEngine has done with their ability to edit extensions, so I wanted the control to be configurable in this way
  3. It had to be asynchronous – when a user posts a comment, I don’t want the whole page to refresh

The final solution is pretty close to what I had in mind.  The extension is a single file that needs to be inserted into the ‘/App_Code/Controls’ folder.  In addition, two lines of code need to be added/modified in the ‘/User controls/CommentView.ascx’ file.

Just a quick note to anyone who may want to implement this on your own.  I have noticed that once in a while, when using IE, I get an error that BlogEngine is not defined and the error points to the following file: ‘/js.axd?path=%2fadmin%2fwidget.js&v=’. The changes involved shouldn’t have any effect on this, but I am not 100% sure if this is due to my code or not. If it is, hopefully I’ll figure it out in the next day or so, as I’m way to tired right now. [ this should now be fixed in the 0.95 version ]

To implement the Recaptcha control, the following steps need to be taken:

  1. Download, extract the file in it, and place the file in the /App_Code/Controls folder.
  2. Open ‘/User controls/CommentView.ascx’ in the editor of your choice and put in the following line at the spot where you would like your control to appear.  On this blog, the code is right above the submit button when posting comments.

    <blog:RecaptchaControl ID="recaptcha" runat="server" TabIndex="8" /><br />

    In the example above, I also put in an extra line break for some extra white space.  I have also put in a TabIndex ( and changed the TabIndex of the submit button ).
  3. The onClick event on the actual submit button needs to change. If you have not modified the code at all, the submit button should look like this:

    <input type="button" id="btnSaveAjax" value="<%=Resources.labels.saveComment %>" onclick="return BlogEngine.validateAndSubmitCommentForm()" tabindex="7" />

    For the recaptcha code to work, the submit button needs to change to the following:

    <input type="button" id="btnSaveAjax" value="<%=Resources.labels.saveComment %>" onclick="return validateWithRecaptcha()" tabindex="9" />

That’s it.  No recompile is needed, and the Recaptcha control should be functional.  If you go to your extensions section, you’ll notice that the Recaptcha control is there and available for editing.  You can ( and probably should ) create your own account on Recaptcha.netand put in a Public and Private key that corresponds to your site. The keys in there are for my site, but they are “global” keys which should work from any domain. You can also disable the control altogether, change it so it does not appear for logged in users, and change the theme.

The control also allows you to create a custom theme.  To do so, you need to specify the name of the theme directly in the tag in the CommentView.ascx file mentioned above. So, for example:

<blog:RecaptchaControl ID="recaptcha" runat="server" TabIndex="8" Theme=”MyCustomTheme” />

You’ll find the rest of the info about what you need to do to skin the Recaptcha on their site.

As always, let me know if you’d like to see anything added to the control, or if you experience any bugs with it.  I’ll be looking into the bug mentioned above this weekend to determine if the control is actually causing this issue mentioned above.  I have a feeling I know how to fix it even if it isn’t, but I’ll just have to run some tests…

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Web Development

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About Filip Stanek

Death Note Pic I'm a developer at ACG in Cincinnati, OH. I like ASP.NET, Flash, and other web technologies, & enjoy playing chess, video games, etc.

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