1

00:00:00,210 --> 00:00:06,120

All right, in the last lecture, we did talk about the working of asymmetric encryption.



2

00:00:06,540 --> 00:00:09,000

Now we will talk about the walking.



3

00:00:09,150 --> 00:00:13,990

I'm sorry, in the last lecture, we talked about the asymmetric encryption in this lecture.



4

00:00:14,010 --> 00:00:17,540

We will talk about working of asymmetric encryption.



5

00:00:17,970 --> 00:00:22,440

So right here we have our phone, Bob, and we have Alice.



6

00:00:22,440 --> 00:00:27,390

Now, Bob wants to send some important documents to Alice over the Internet.



7

00:00:27,390 --> 00:00:35,010

So let us see, using asymmetric encryption how he can securely send those important documents.



8

00:00:35,550 --> 00:00:42,270

Well, let us consider this is the original document that Bob has and he cannot send the document as



9

00:00:42,270 --> 00:00:42,540

it is.



10

00:00:42,540 --> 00:00:42,930

Right.



11

00:00:43,080 --> 00:00:47,250

He has to encrypt it because he wants to send it securely.



12

00:00:47,790 --> 00:00:50,870

So this is Alice's public, right.



13

00:00:52,020 --> 00:00:59,390

So if any one of you or has confirmed that you have to encrypt with public key and then decrypt with



14

00:00:59,400 --> 00:01:06,420

private key of the same person, then you are right now, if if I wanted to encrypted private key,



15

00:01:07,140 --> 00:01:11,100

it's not possible because I don't have the other person's private key.



16

00:01:11,100 --> 00:01:13,320

It has to be it.



17

00:01:13,500 --> 00:01:16,410

The private key is supposed to be with the person himself.



18

00:01:16,410 --> 00:01:22,010

You're not allowed to share your private key or the app doesn't allow them to share the private keys.



19

00:01:22,710 --> 00:01:28,050

So what you can do is you can take the public key, which is publicly available, so you can take the



20

00:01:28,050 --> 00:01:37,390

public key, you can use encryption algorithm and then you can get the encrypted document.



21

00:01:38,160 --> 00:01:45,490

Finally, what you can do now, once you have this encrypted document, it's encrypted with the public



22

00:01:45,820 --> 00:01:47,110

right of public.



23

00:01:47,640 --> 00:01:50,310

You will send this document now.



24

00:01:50,340 --> 00:01:53,520

Alice will receive this encrypted document.



25

00:01:54,060 --> 00:02:02,160

What she will do is she will use her private key, because if you have encrypted with a public key,



26

00:02:02,160 --> 00:02:04,590

you can only decrypt with private key.



27

00:02:04,950 --> 00:02:11,880

And since Bob has encrypted with Alice's public key, she can only decrypt with her private key.



28

00:02:12,480 --> 00:02:14,800

And Alice's private key is with her.



29

00:02:15,210 --> 00:02:22,080

So Alice can then run the decryption algorithm and then she will get the original document.



30

00:02:22,790 --> 00:02:30,560

So what you can understand here is this is the encryption process and this is the decryption process.



31

00:02:30,900 --> 00:02:37,980

So in this way, these two different keys are used for asymmetric encryption.



32

00:02:38,520 --> 00:02:46,590

So the bottom line here is you have to encrypt with the receiver's public key and then you have to decrypt



33

00:02:46,590 --> 00:02:48,480

with receiver's private key.



34

00:02:48,960 --> 00:02:52,400

This is the base working of asymmetric encryption.



35

00:02:52,800 --> 00:02:59,910

Make sure that you understand understood this working because this is the exact same working we are



36

00:02:59,910 --> 00:03:03,450

going to use in case of digital signature algorithm.



37

00:03:03,990 --> 00:03:10,920

Now, since here there are two different keys used, the protection is more, but again, it takes more



38

00:03:10,920 --> 00:03:11,250

time.



39

00:03:11,280 --> 00:03:14,730

So right now you're only seeing only one document.



40

00:03:14,730 --> 00:03:20,630

But in the Internet, thousands of millions of documents and e-mails get exchanged in one second.



41

00:03:21,060 --> 00:03:27,520

So, you know, you have to have some method in order to make symmetric encryption work.



42

00:03:27,540 --> 00:03:34,350

So what is that method we will see in the next lecture where we'll have a look at the Diffie Hellman



43

00:03:34,770 --> 00:03:36,610

key exchange algorithm.



44

00:03:37,110 --> 00:03:43,320

So if you have any doubts regarding asymmetric encryption or symmetric encryption, you may ask us through



45

00:03:43,320 --> 00:03:45,200

the question and answer portal.



46

00:03:45,210 --> 00:03:47,640

We are always welcome to solve your doubts.



47

00:03:48,060 --> 00:03:48,510

All right.



48

00:03:48,900 --> 00:03:53,220

Let us get started now with Diffie Helmond Exchange algorithm.