Well, in today's world, you cannot sign the document then, you know, you send it to your postman
and the postman will transfer overseas, you don't do that anymore.
It will take a lot of time.
That's why the concept of digital signatures is introduced.
And cryptography is again to the rescue of security.
So digital signatures are basically it's a kind of authentication that, you know, tells the receiver
that, OK, the sender has signed and he is he's agreeing with what is present in the document.
So it helps in a secure transmission of information.
And it validates and instead of a real signature, a digital signature is also a proof that the document
is a legitimate document.
Every digital signature works on Piqué.
That is the public key infrastructure.
Now, public key infrastructure is a unique set of requirements that help in the working of digital
signatures.
So it's basically a framework of cryptography that employs many such things like digital signatures,
private keys, public key certificate, the authority.
Well, what is certificate authority?
So Certificate Authority is a third party organization that have been widely accepted as reliable for
ensuring security in the same way.
Let's consider this.
All of you might have heard of the University of Harvard or Stanford or M.I.T. or Oxford game, but
these are some of the known institutes.
Now, if there is a YouTube channel of a person who is, you know, who's teaching some things which
are taught in the scene, the exactly same fee in the Harvard University, and he says that I'll give
you a certificate.
And, you know, this is a valid certificate.
You can show this certificate and you'll get a job.
And let's say there's a guy who already has a certificate from the Harvard University, OK?
He doesn't have the certificate from this guy who's teaching on YouTube, but he has the university
from Harvard.
He has that degree.
So what do you think people will trust which degree the most, even though both the persons of same
knowledge, would the people have some knowledge of which degree is more trusted, but obviously the
one from Harvard, because they are established universities, which have been widely accepted by many
students in giving this certificate in the same the certificate authorities are entities or organizations
which have been widely accepted as the status quo.
For example, if Howard says this guy is a legitimate engineer, then that guy is a legitimate engineer.
In the same way, if certificate authorities give certificate to Alice, then she is alleged to have
verified her identity.
And no one is going to doubt that because these certificate authorities are very highly functioning
organizations.
They have detailed processes.
Then there is no wrongdoing in those organizations.
No process is just a simple process.
They all have a detailed framework and many operations and processes take place to make certificate
authorities work.
So it is a combination of all such things which makes the working of digital signatures possible.
So you can consider digital signatures as actual signatures just sent over the email.
So instead of you signing the document and then posting it to overseas, you have to just attach your
digital signature.
Now, the next obvious question in mind would be, well, what is a digital signature?
What exactly does it look like or how do I see a document has a digital signature?
Then obviously I have a new lecture on that.
So without wasting any time in the next lecture, will straight talk about will have a good talk about
the working of digital signatures.
So and it's a warning for you that if you have forgot about if you have forgotten about public encryption,
which is asymmetric encryption and harshing, I would request you to please revise those topics because
digital signatures do make use of asymmetric encryption.
And has.
All right.
In the next lecture, we'll see the working of digital signatures.