Beginner PHP Tutorial - 96 - MD5 Encryption Part 1 Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

hi this is Alex from PHP academy' 2 org
back with another PHP tutorial for the
new Boston now in this video we're going
to be talking about md5 encryption or
rather generating an md5 hash from a
string now if you if you don't know what
md5 is I'll make I'll take a couple of
seconds to just explain md5 is a form of
encryption and a hash is generated from
a string that is given and in PHP we
have a function called md5 and what this
does is if you supply a string in here
it will convert this string to an md5
hash so let's take a look at a couple of
examples let's create a string that
might possibly be a password so I'm
going to call this I'm going to give
this a value of password so our password
essentially is password now if we want
to encrypt this we could simply echo out
or create a new variable say string hash
and I'm going to make this equal to md5
and then it in the bracket I'm going to
supply the string data that I want to
convert or rather encrypt now I'm just
going to come down here and echo out
string hash ok so now let's take a look
at password what it looks like with an M
when it's been hashed pass air in line 8
ok oh yeah sorry semicolon on the end of
there so let's refresh ok so what you
see now is the hash representation of
the string password now however much we
refresh this it's going to stay exactly
the same so let's keep refreshing is
exactly the same so we call this one-way
encryption this string this hash cannot
be decrypted back to normal text the
only way we can do this is take an input
and match it to the actual hashed
version of the input so for example if
you had a password stored in a database
with this value which we are going to
come on to talk about in a minute and
give a short example if you had a
password stored as 1/2
and the user typed in say Alex as the
password the hash for Alex wouldn't
match the hash for this
therefore the password would be
incorrect now if we were to hash
password again if password was entered
via user input and and we hashed
password again it would match this
therefore we would ask you what we know
that the password is the same so if this
doesn't make sense I'm going to create a
new file and I'm going to copy and paste
this hash over into this file so paste
it in there and we're going to call this
hash dot txt
so obviously this would be an unsecure
way of storing a password because
someone would be able to access it
however what I'm going to do now is from
index.php is I'm going to let the user
enter a value so we're going to create a
form that allows the user to enter a
value then when the form is submitted
we're going to open hash dot txt we're
going to look at the contents and I'm
going to see if the password matches
bear in mind this this is equal to
password so if we were to type in Alex
this the password would be incorrect how
it however if we were to type in
password this would be correct so let's
begin creating what we'll get rid of
this first of all and let's begin
creating our form so form action equals
index or PHP the method is going to be
post remember we're posting a password
so we want to keep it out of sight so
we're going to use post
and when you are sort of using login
forms or register forms you should
always use the post method as well
because we've got a lot of data as a
process as well as we wanted it to look
as clean as possible so now I'm going to
create a label called password or some
text called password and the input type
would usually be password but for the
purposes of this tutorial I'm going to
use text just so we can see the text
that we're typing in and the name of
this is going to be user underscore
password okay so let's break down a
couple of lines and create a submit
button and the value of this is going to
be submit so let's just refresh the page
and check that looks okay okay so we've
got the option to type in the password
here you can see what I'm typing whereas
if we were to use the password type we
should obviously always use for
passwords then we wouldn't be able to
see the data so let me just change this
back to text okay so the next thing we
want to do is up here we want to check
that a password has been entered into
the box and the form itself has been
submitted so we do this we start an if
statement and this here is going to be
the block that runs if this is evaluated
to true so the first thing we need to
check is if the the input type has been
set therefore the form has been
submitted so we can say is set post user
underscore password and we're also going
to check if the password isn't blank so
we're going to say is not empty not a
semicolon there sorry and then we're
going to specify this post again so user
password okay
so presuming that the form has been set
and the password has been entered we're
now going to echo out something just to
confirm this to us as programmers before
we continue to the next step so let me
type M let me just refresh the page
first of all let me just type a password
in here
and I'm going to click Submit and you
can see that we've got this little
message confirmation message coming back
however if I submit it without any data
in nothing happens so the user is going
to have to type in a password we could
we could also let's say else here we
could echo please enter a password okay
so obviously we're not going to be a
curing out okay to the user that was
just for our benefit now the next stage
is to set a new variable with this with
this password value it it's not
necessary but it just allows us to
program a lot quicker so we're going to
say user underscore password you can
name this variable anything you like and
that is going to equal dollar underscore
post and then user password so we're
just creating a shorthand way to
reference this posted variable if we
reference this outside of this if
statement we made we may come across an
undefined index error so we reference
this inside here okay so the next thing
to do is to open up this file called
hash text and we want to grab this value
here and then compare it to the password
that's entered now we're obviously not
directly comparing it because if we were
directly comparing it the user would
have to type this password hash in or if
we were storing it as plain text we
wouldn't have to do anything to it
because that would avoid the point of
talking about md5 hashes