Beginner PHP Tutorial - 164 - Creating Captcha Image Security Part 1 Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

hello this is Alex from PHP academy' dog
back with another video tutorial for the
new Boston now in this tutorial we're
looking at using the GHD library with
PHP to generate an image based on a
security code that we're going to make
look much like this so it's a hard to
read M code so it's going to be hard to
read by bots that may be browsing data
forms of browsing trying to submit forms
obviously they're freely accessible to
submit data through but if we add this
simple functionality to perform it makes
it harder to see so that's basically
what we're going to be creating we're
going to be using this creating this
obviously in PHP but we're going to be
using the GE library to generate our
numbers we're going to have four
characters you can see if I if I just
refresh the page you can see that these
numbers and in fact the the debtor the
lines to skip the squiggly lines around
them the noise if you like change as
well so we're going to learn how to
create one of these forms and then we're
going to learn how to create well first
of all the image itself we're going to
learn how to create and then what we'll
do is we're going to learn to create
this little form here that allows us to
actually match them so at the moment I
can see an 8 a 3 a 1 I think an 8 so if
I type 8 3 also at 8 3 1 & 8 and I click
Submit we have this little confirmation
up here a match now if I was to type the
code in wrong so I could type 9 9 9 9 in
here and click Submit you can see it
says invalid code try again here I've
got 3 7 double 0 I think click Submit
and a match so you can see how you know
this is quite flowing you can add it
straight into your form as well so when
you submit your form this must match as
well and every time you resubmit a form
say the user gets it wrong you can keep
your data but you this will always
change and
they'll have to try again so the first
thing we need to do let's talk about the
flow of the program because we need to
establish how we're going to do this
before we actually do it now if you've
already seen my tutorial on creating
text to images then this will make a lot
more sense so please if you haven't
already watched that go back and have a
look at the text image tutorial it will
but it basically covers converting an
email address to an image in order to
maintain some level of security on a
website with regards to spam and bots
scanning through and taking email
addresses so have a look at that
tutorial in your learn the 90% of what
we're going to be doing in this tutorial
so it's very important you understand
how to create images from text using GD
first of all second of all if you know
how if you know all of this you need to
ensure that you've got Gd installed I'm
using an X amp package so PHP comes with
GD automatically installed the third
thing to bear in mind is that the flow
of the program and how it works so we
need to think about first of all what
we're doing here now the random numbers
that you see are using the generated
using the round function in PHP now what
we're doing is we're setting this as a
session now because we're setting this
as a session it means that when we
submit our page we can check whether
it's already submitted and if it is
submitted if we have submitted our form
we can we can make the well if basically
the flow of it is is that you type in
your code here so we can type a thousand
for example and it says invalid code try
again so asks us to try again so we we
try the code one and we store this value
in a session so it's saved in a session
which means that when we generate the
image file itself in generate PHP
so let's go over to generate PHP you can
see this is where the image stems from
and obviously the the numbers the same
with regards to this however because we
are setting the session on the index
file this will change each time so if
this doesn't make sense then it will
when we go into the code the third thing
you have to bear in mind is that we're
using true type fonts then you can see
that this fonts are sort of squirrely
fun I've called that inside my inside my
fire I've called that font TF F or t TF
sorry because it's a true type font so
we're going to be using in introducing a
different function and this is called
image TTFN text so we're creating text
in an image format but we're using a
true type font and we're going to import
that file as well or at least
incorporate it into this function and
this function takes a couple more
parameters that we haven't already
looked at in other tutorials we're also
going to be looking at the image line
function as well so if you'd like to
read up on them beforehand please feel
free to do so say you understand the
tutorial a lot better otherwise we're
going to crack straight on with the code
okay so now we're into generate dot PHP
file there's a few things we need to do
before we do anything else well the
first thing is we need to change the
content type of the page and we do this
using the header function so if you've
seen the other tutorials on the GED
library you'll know that we have to
change the header type in order to
process this generator PHP file as an
image in itself so we're going to say
content type and this is image forward
slash jpg so we're changing the content
of this page now to a JPEG image which
is perfect because we're outputting our
capture image if you like as a JPEG
image okay so the next thing we need to
do is set up a few variables or a couple
of variables just to ensure now we know
what we're doing now the first one is
the
Exce that we're going to be inputting
into or processing as an image so I'm
going to create a variable called text
and this is equal to dollar underscore
session and I've called my cool the
variable secured so if we're going to
index dot PHP let's first of all set
start sessions so a session start and
then what we're doing is we're going to
be generating this here so whilst I'm
programming in here in generate PHP I
want to ensure that it's defined first
of all in index dot PHP and we've
generated a random number so in here I'm
simply going to say dollar underscore
session secure equals Rand and we're
generating a random number between a
thousand and nine nine nine nine so this
is going to give us a for a figure
number