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Image Verification (updated)
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Email
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| Submitted on: |
10/4/2002 2:02:50 PM |
| By: |
Dracarys
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| Level: |
Intermediate |
| User Rating: |
By 14 Users |
| Compatibility: |
PHP 4.0 |
| Views: |
49593 |
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(About the author) |
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This tutorial will show you how to make an image verification
like they use (used?) on Yahoo or they still do on Planet Source
Code. It is quite useful in order to prevent users from writing
scripts that would do the voting, posting or whatever. Now,
whenever a user wants to vote for something, he gets an image
with a randomly generated string, that consists of uppercase and
lowercase characters and numbers from 0 to 9.
He then has to enter the string he sees on the picture and only
if the code is correct, he will be allowed to proceed.
I hope this code will help you. I admit, i took the idea from
a recent post on Planet Source Code. (canŽt remember, who it was) But the method used was too
unsecure and relied on posting variables. :)
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Other 1 submission(s) by this author
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Your Vote
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Other User Comments
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 10/4/2002 2:48:13 PM: Dracarys
Ok, please leave your feedback and comments here! :D
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10/4/2002 4:39:56 PM: Charles Chadwick
Very nice. Extremely simple and easy to understand, and you did a great job commenting the source (which a lot of people on PSC don't bother doing). Keep up the great work, I look forward to seeing more code from you in the future.
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10/4/2002 5:03:47 PM: Alex Graf
@Charles Chadwick:
Hi! Thank you for your comment and valuable vote. I tried to write a mail to you but it said: "Mailbox not available"
Well, i think, commenting is very important. If you look at your code a year later, you will not be able to recognize it without comments or a good structure.
So, again thank you. :D
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10/4/2002 5:06:33 PM: Alex Graf
Bloody switching of names. :D I think
the scripts are not perfect here. :) (Dracarys=Me)
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10/5/2002 8:16:33 AM:
Hello, I read your code, it's very nice and simple, but i think that you should use the cookies instead of the session, cause i have a very bad experience with session and that is it forces the page to reload if you come back to it. Let's say that you put this verification where user has to enter 20 fields of information and he entered a bad verification and submited the form code, so when he comes back to the previous form he'll find al the fields empty!!! i think that this will piss him off. I don't know if you have an idea to handle this situation, if you do please let me know of it. I give you 5 stars
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10/5/2002 8:26:44 AM: Alex Graf
Hello. Well, this is true, of course. But i thought about it a while. First: Not every user accepts cookies. Second: You donŽt have to press reload, as it does this automatically, thus, creating a new code.
But, alright, I will try, if i can do it with cookies AND sessions. So, if the user doesnŽt allow cookies, sessions are used.
IŽll post the code, if iŽm ready. :)
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10/5/2002 8:28:04 AM: Alex Graf
Oh, and thanks for your vote! :D
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10/6/2002 1:18:52 AM: Darryl Porter
I worte the same code last month--you should check out the update version--it doesn't use post variables. It was updated one day after it was posted.
And it is very secure now!
imatation is the best form of flattery.
(If this comment was disrespectful, please report it.)
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10/6/2002 2:50:48 PM: Alex Graf
@Darryl Porter: Hi! Thanks for your note. IŽll have a look at it right now. But please believe me, i never intended to write the same code or steal it. :( I only read your code the day you posted it. Then, a week ago, I needed the same code for my HP and remembered, there was only yours, and it used passed variables. So I wrote my own and posted it here too. IŽm sorry, if I did offend you. Again, please believe me, I didnt intend to. Greets, Alex
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10/7/2002 2:17:19 AM: Darryl Porter
Good code. Alot cleaner than mine.
I'm working on a web site right now--and am unable to divide my time--thanks for the offer. If you keep working on it, I'd like to se what you produce.
(If this comment was disrespectful, please report it.)
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10/7/2002 2:23:59 AM: Dracarys
@Darryl Porter: Thanks, but same goes for me. But i think, IŽll work on it again at christmas. :)
(If this comment was disrespectful, please report it.)
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10/27/2002 12:33:09 PM: John Manavalan
My Dear I cant see any Picture in My Computer.
I am using windows2000
(If this comment was disrespectful, please report it.)
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10/27/2002 12:36:45 PM: John Manavalan
plz reply
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10/27/2002 4:40:53 PM: Dracarys
@John Manavalan: Well, as i mentioned, you need the GD library with PNG support. In addition your browser need to accept PNGs. So does your webserver. If you disabled PNGs in your server software, you will see nothing. Please check this first.
(If this comment was disrespectful, please report it.)
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11/22/2002 2:23:47 PM:
Hi,
thanks for your codes. But when i use it, the pix isn't display. Just a
(If this comment was disrespectful, please report it.)
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12/7/2003 9:26:05 AM:
Excellent gr8 job. for a fact most novices like me need to know that gd library can be enabled by editing the php.ini and removing the ; before gd2.dll and specifying the correct path for extension..
(If this comment was disrespectful, please report it.)
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2/28/2004 9:47:23 AM: Santium
Great job. 5/5
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1/27/2005 9:46:15 PM:
Line 7 of verificate.php should be
$IMGVER_EnteredText = $_POST[
(If this comment was disrespectful, please report it.)
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1/27/2005 9:47:45 PM:
er, $HTTP_POST_VARS should be $_POST (since the comment was truncated).
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3/8/2005 2:45:27 AM:
hello.. alll
Would you help me..
I've download it code and I copied into my directory.. but why the image can't displayed
it copyed at http://www.embun.net/capcha/
best regards.
setiawan77th
(If this comment was disrespectful, please report it.)
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3/13/2005 10:10:15 AM: Jonathan Moseley
@setiawan77th, GD isnt supported.
"Fatal error: Call to undefined function: imagecreate() in /home/sloki/user/t86556/sites/embun.net/www/capcha/doimg.php on line 11"
(If this comment was disrespectful, please report it.)
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7/27/2005 12:32:11 AM: Damian Yerrick
How does this gracefully degrade for users who use a screen reader or a refreshable Braille terminal?
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8/16/2007 2:41:50 PM: Shawon Khan
nice work ......
realy 'class A' work.......
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