Beginner PHP Tutorial - 167 - Creating Captcha Image Security Part 4 Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

so now obviously this image is useless
without our user input so what we want
to do is we want to we've already broken
down a line we want to create a form and
this form is going to submit to this
index.php page and it's going to check
that the GD value in fact no we're going
to submit to another page I think that's
probably a bit better and the reason
we're submitting to another page is is
what we're doing is we are refreshing
when we come back on ourselves so we've
got form action equals check PHP that's
absolutely fine and now in fact we will
go back to the index page right okay so
now we need to say type the value equal
value you see okay and then we can
create an input type of text and we'll
give this the size of six just to keep
things quite neat and then I'm going to
say a name is secure and then obviously
we need a submit button
so we'll preview this in a moment to
make sure we like the look of it so
submit for the value okay so let's start
preview this and see what we think
okay so type the value you see we're
going to type the value in here and then
we're going to click Submit okay so at
the moment nothing's happening cuz we
haven't created a process for this but
up here what we want to do now is we
want to say if the form has been
submitted so if the user has submitted
the form we don't want to generate a
random number just yet so if is set and
the variable that we're taking into
account is this post variable secured
down here so dollar underscore post and
that is secure so if is set or if not
set we can generate a number
otherwise we can do some some validation
of this so what we can say is we can say
else and we can say if dollar underscore
session secured is equal to dollar
underscore post secured so essentially
what we're saying is if the session
that's been set so the random number
that's been set and displayed in our
image is equal to the post that the user
has made so the images that the letter
or the numbers so that they've seen then
we can do something so we can say echo
success or or a match for example
otherwise we can say echo incorrect try
again and then this is important what we
need to do is we need to generate
another one of these because they've got
it incorrect therefore we want to change
the value so they have to look at
another another value without this what
we're going to just be doing is
displaying the same value to them now
for this example where we're echoing out
a match but this could be part of your
form validation so if you're validating
say I user name password a first name
and a surname you'd want to include the
relevant checks in there then register
your user then forward them into another
page you wouldn't be forwarding back to
the same page and if I was to say yet
successful we wouldn't be showing the
registration form so hopefully that
makes sense to you let's refresh the
page so let's try and have a look at
this image according to everything I've
written hopefully this works now the
first thing I'm going to do is I'm going
to type in the correct image to see
where the corrector numbers to see what
we get up so three to eight four let's
click Submit okay so it's as a match
let's just create a break before this
image to make everything look a bit
neater to refresh that so we've got a
match so we've got three to eight four
we typed in three to wait for that's
fine now let's type in
well presumably this now would have
registered the user and gone to another
page so let's go back onto your next up
PHP and generate another number so
you've got 4 9 6 8 here let's type in 1
2 3 4 we click Submit now what it says
is incorrect try again it's generated a
new number so now I can't make this out
I think it's 7 4 7 7 let's try 7 4 7 7
click Submit incorrect try again 4 5 9 3
submit and it says a match say 4 5 9 3
it successful we've successfully you
know typed in the number so we're saying
a match and we've still kept this number
here but obviously would be something
forwarding the user elsewhere at this
point but you can see that the most
important part about this is if the user
gets it wrong that generated a new
number to try so every time they get it
wrong generating a new number to try so
this is basically capture in PHP with
the GD library and how we generate a
random number you can use letters as
well that's perfectly acceptable we're
generating a random number displaying it
as an image with these lines to ensure
that it can't well it might be able to
be read by some sort of robots I mean
things again clever but at this point
it's hard to be read and by a robot on a
basic level but our user can still see
it and we've processed it this through
form validation so not only if we
generated this image we've tried it out
in our own little form