Wednesday, 4th April 2007Free ASP Form Image Code Verification (CAPTCHA) Script using OverPower.ImageLib

A CAPTCHA script for Image Form Verification using OverPower.ImageLib (which is free!)

By popular demand I've written a script for Form Verification that uses a freely available image library - in this case, "OverPower" (download it free here)

Now while I'd love to claim the fame for finding this little gem, it was the wonderful Bill Woodland of www.squeekasp.com that emailed me all sorts of info - thanks Bill! Bill has written all manner of scripts for this free library so if your looking for something specific or special - he is "The One".

For anyone wishing to tweak the script or if your looking for information generally on using the OverPower.dll component, check out the Object Reference here.

Addendum

Bill contacted me today and has reworked and improved my original script, incoorporating the OverPower and ASPJpeg support all in to one master script - both my original script and Bill''s Uberscript are included in the downloadable zip file.

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Article Comments

  • 27

    Cleverson Alexandre, 18:09
    15 September 2008

    Muito bom.

  • 26

    Bob, 12:27
    22 August 2008

    Hi Thomas,

    Many apologies - we recently re-worked our website and have been working through the broken links.

    All links are now fixed including the downloads and object reference.

    Regards

    Bob

  • 25

    Thomas, 10:27
    15 August 2008

    Why can't I download any of this ?
    The links seem to be broken...

  • 24

    DavidS, 14:22
    20 November 2007

    Nevermind...It was case sensitive. Regards...

  • 23

    DavidS, 14:21
    20 November 2007

    Thanks...I'm having a problem though. I can see the verification box and when I type the letters I see it always comes back saying incorrect verification code. Any suggestions.

  • 22

    David, 13:35
    26 September 2007

    Thanks dude! I was needing a simple fix for an app that is coming off line soon. We have been getting form spammed about 10 times a day from too many random IP's to seriously devote time to tracking things down.

  • 21

    Sarah, 15:45
    20 June 2007

    Thanks Bob. I did get it up and working on the production server. Yea!

    Thanks for the great tool!

  • 20

    Bob, 15:03
    20 June 2007

    I'm afraid I don't really know what else to suggest!

    Everything I've read on Google points to the Invalid Class String being caused by improper registration:

    See here

  • 19

    Sarah, 14:09
    20 June 2007

    Yes I did receive a confirmation message. About the only thing I haven't done is reboot - *laughs* probably should. Everyone, IUSR and IWAM have full control.
    -Sarah

  • 18

    Bob, 14:06
    20 June 2007

    Hi Sarah,
    Apologies for asking but I have to check, when you registered the DLL with regsvr32.exe did you get a confirmation message? If the object is in place and has the correct permissions, I can only assume that its not registered in Windows.
    Unfortunately I've never installed this on Windows as I've always run a development server.
    Bob

  • 17

    Sarah, 13:47
    20 June 2007

    Hi Bob. I'm having the same issue as Violet. I have installed the dll. Everyone has full control. (I'm using XP - this will be eventually moved to a 2003 server). I have added IWAM and IUSR. Ideas?
    thanks - Sarah

  • 16

    Bob, 15:53
    17 May 2007

    Violet,

    IUSR
    Yep thats exactly what you need to do - as your on a home network and there's no real danger, I'd just give all the users I could find full access. After you've clicked "Add" on the security tab, try clicking "Advanced" and then "Find Now" - this should display a list of all users and groups currently installed. Its worth adding IWAM_ as well.

    VISTA
    I've been keeping abreast of Vista and personally I'm advising all of my clients to stay away from it for a while - there's still A LOT of bugs in it and I'm sure that when its polished it will be very secure but at present, I think there are still flaws. I'm also assuming that it will be much more taxing on system resources.

    If your planning on doing a lot of website development, personally I'd recommend getting an old P3 pc from a skip or antique shop and installing a copy of Windows Server on it as a test bed.

    I'm glad to see your persevering with this!

  • 15

    Violet, 14:42
    17 May 2007

    Hi Bob :)

    Yes, I'm developing & testing everything on my PC before I launch the site. OK so what I should be trying to do is getting the IUSR to show up when I right-click click overpower.dll & choose properties > security. I'm wondering how 'deprecated' my OS (XP) is. Are a lot of people on Vista already? Hmm..

  • 14

    Bob, 13:51
    17 May 2007

    Whoa - apologies for any confusion there - the ordering of comments wasn't working as it should - all fixed now.

  • 13

    Bob, 13:20
    17 May 2007

    Violet,

    The list of users you see on the security tab for OverPower.dll isn't a complete list if available users - its just the users that have permissions on that file.

    I must confess however that I've just discovered that there isn't an everyone user on XP (I haven't ran IIS on XP for years as I've always had a server) so I'm assuming that just the IUSR account will do the trick.

    Presumably your developing this on a home PC before launching it on a server?

  • 12

    Violet, 12:42
    17 May 2007

    Bob,
    Actually, it's the strangest thing. It seems I "had" an IUSR_PCName because it took me forever to setup IIS on this computer & I kept running into that profile in the Security tab area. However when I right-click on overpower.dll > Properties > Security I don't see IUSR_PCName anymore.. THere's a Power Users & MyPCName\Users but there's no IUSR_PCName. I'm wondering if this has something to do with it: my windows (XP) is installed in folder c:\windows2 & not c:\windows, but I'm pretty sure I installed overpower.dll in c:\windows2\system.. Not sure what I'm doing wrong..

  • 11

    Bob, 12:32
    17 May 2007

    Violet,
    I'm assuming your running Windows XP? Your computer should definitely have an Everyone group - its built in to Windows (as are various others such as Administrators, IUSR_PCNAME, etc). When you click the security tab, it lists the users currently listed for that item - if you can't see Everyone, you need to click Add and type "Everyone" in the box that says "Enter the object names to select" then click Ok, it should now appear on the security tab.

    Let me know how you get on!

  • 10

    Violet, 12:18
    17 May 2007

    Hi Bob ^_^

    This is the error message that Dreamweaver is giving me:

    Error Type:
    Server object, ASP 0177 (0x800401F3)
    Invalid class string
    /violet/imageVerification.asp, line 82

    Actually I did get a confirmation message, but the image still won't show.. I don't have an Everyone profile in the Security tab but I've given all users (there are only 2 computers on this home network..) Full Control

  • 9

    Bob, 12:03
    17 May 2007

    Violet,

    Is the full error you are getting "Server.CreateObject Failed Invalid class string"? If so, this points to the ASP component (in this case "OverPower.dll" not being installed properly - I'd double check that the "regsvr32 c:\windows\system\overpower.dll" command completed properly (you should get a confirmation message) and also that you've allowed full control to "everyone" under the security settings.

    If this doesn't do it, please post more error message details here.

  • 8

    Violet, 11:56
    17 May 2007

    Hi Bob, really really sorry for the double posts. I was expecting to see my post the minute I hit submit.. Sorry.

    I've tried using both ASPjpeg & OverPower. I installed overpower.dll into my system folder, but to be completely honest with you, I don't even really know I can do with it. I tried to use it with the ASP files included but couldn't get it to show up.

    As for "it works here," what I meant by that was that I see a working version of the CAPTCHA here at Freshmango.com (I love the layout, by the way :)) in your site, on this page, but only the ALT tag shows when I try to view it locally (localhost).. I guess what that means is that I'm doing something wrong (or maybe my settings are wrong?), but I'm not sure what that is. I also get an invalid class string when I try to view ImageVerification.asp..

  • 7

    Bob, 10:48
    17 May 2007

    Hi Violet,

    Not sure what you mean by "it works here" - also - you've posted a message both for the OverPower based script and the ASPJpeg based script - which component are you trying to use?

    Thanks

    Bob

  • 6

    Violet, 01:08
    17 May 2007

    Desperate to get this to work. No image shows. I see the ALT tag but there is no image.

  • 5

    George Mahnke, 10:56
    10 May 2007

    I just downloaded and installed this free component for one of my clients. It works great. What a find! Most development is moving towards .NET platforms, but in the case that some ASP sites still are out there this is a true gem. Thanks!

  • 4

    Bob, 09:55
    02 May 2007

    Vasily,

    It sounds as though your browser cache settings are not fetching the new image - there is an easy way around it however - in the image tag, simple add an ever changing querystring to end of the file name, the easiest way to do this would using the "now" vbscript function so the original:

    <img src"imageVerification.asp">

    would change to:

    <img src"imageVerification.asp?noCache=<%=now%>">

    Let me know how you get on!

  • 3

    vasily, 23:47
    01 May 2007

    Good morning Bob!

    Right now I checked your own verification system here -> http://www.freshmango.com/articles/display/?articleID=26& . This is a link you sent me yesterday and when the page been loaded I got yesterday's verification code image - no changes. It appears that the code is changed only when browser's "refresh" button been used/

    Is it possible to do something ?

    With best wishes
    Vasily

    PS. Ooops! One more tricky thing ! Right now I entered the code displayed (this is yesterday's one still on the image) and got a response "Incorrect Verification Code"). Now I will use a "refresh" button - hopefuly you'll receive my message !

    PPS. I'm using IE6

  • 2

    Bob, 11:22
    01 May 2007

    Hi Vasily,

    It sounds like the image may be being cached or that RANDOMIZE hasn't been invoked in the script, can you confirm a couple of things for me:

    1) Which script are you using, the combined script (for ASPJpeg as well) or the standalone script?

    2) The web address you posted doesn't seem to work - do you have another?

    Bob

  • 1

    vasily, 09:18
    01 May 2007

    Good day,

    Thanks for your code - well done. I've just start using on www.dogexpo.info/pradd.asp/

    Can you please gimme a clue:
    1. I'm checking user entry on the server-side and redirecting back (with "response.redirect" method)if some a wrong data exists.
    2. In this case Verification code always appears to be the same/
    3. Even when leaving a page with this code and then coming back - the code never changes as well/

    What can be done ?

    Many thanks in advance and my Best Regards
    vasily