## Fortinet NSE4_FGT-7.2 — FortiGate Firewall — Section 1: FortiGate Firewall V6.4 1 Part 48

**66. Lecture-66: Cryptography Symmetric & Asymmetric Encryption.**

Our topic is weapon. But before starting with Pen, we need to know some basic terminologies.

So, let me go through quickly, okay? And that is cryptography. What is cryptography basically is a Greek word. Which, you know, it’s made from two World Cup cryptos and Graffin, it’s a Greek word, cryptography, it means hidden writing, crypto means hidden secret and Grafman means written.

So, that’s why it’s become like a cryptography.

So, basically, this is a method to hide your data, to hide your information, to make them got to be sure that nobody, no third person can understand them. This method, we call them cryptography to make them impossible to read them for any other third party person to scramble the data, to change them, to modify to do something with the data so that nobody else, but only you and the receiver person can know the data.

So, this type of method, we call them cryptography so that nobody can hack my data when data inmotion motion either data and storage.

So, we call them cryptography now and cryptography. There are few terminologies. One is plain because what is plaintext? plainText means the original data, which is readable, clear text data, whatever, like whatever you can see. Now, this is clear text. You can understand that this is in plain English.

So, plain text, clear text when humans can read them and anybody can read them this data, we call them plain text, either clear text. The other one is cybercafes when we convert plain text to noncredible format, garbage data, hidden data, we call them ciphertext. And this convergence is called encryption.

So, encryption is nothing just to scramble your data, just to change the data so that nobody know either to make them noncredible.

So, this method, call them encryption. And when the receiver is sued, the garbage data either type or text.

So, they will apply the same rule to make them plaintext again, readable format.

So, this is, again, plain text and this converging from cyber attacks to cyber attacks to plain text. We call them decryption, so forth. You got involved in certain cryptography, plain text. We convert them to cyber attacks and cyber attacks. We convert them to back to plain text and encryption and decryption. But both parties has to know the method, how you make the data. Hide. And this method in this techniques and this formula we call them encryption algorithm, algorithm is nothing but formula techniques method, which you use to change the data so that nobody knows the data.

So, this is called encryption algorithm. Now, the party who received the data, they helped to apply the same method, the same algorithm to receive the data and clear text. This has got encryption algorithm like in simple words. I will show you from all techniques, you know, encryption is since long time, but in all these people was just changing the word. Normally, I’d give an example. I have very good, very good friends with. And you get so in our area, normally smoking is not allowed in our culture, you know, so so we know what he want to try to smoke.

So, we have a key word to tell us.

So, normally there is a key word he tells me in front of a letter. We know what we sitting with elders who he normally say, let’s go, let’s go. Now, the people understand that they want to go. But actually, you know, and we know these are the key word that you want to smoke, basically.

So, this is called encryption. And I know the method so I can decrypt that you want to smoke.

So, this encryption is since long time, long, long. And I cannot say how long is and there then there is a SESAR site. But as well suppose if I put here. Hello, supposedly only I can choose because an English alphabet. There are 26 characters I can choose anything suppose I say to to miss that change hello to to give one other. And this is Emin’s encryption deeming decryption and choose. Now, Hillary is being changed to Geggie and and and kill after each. What is this hitch. G.H. Because I said to shift the hedge to otherworld e become e f g it’s become G and l become M and the other l become M and or become Q. This is also in crypto what is called encryption. Now do you understand. What is this. Gege Jaeggi and kill. It doesn’t make any sense. It used to be an old days but if you apply this method and nowadays so anybody can hit them because you know and every English word wildwoods are repeated mostly and er these two words is repeated in every word you will see and only 26 character combination.

So, just make a table and draw again J. Q And and look at NSB and so very soon anybody can hit them, this one. But anyway, this is the old method which we call them SESAR Cyper nowadays you will see, you know, I show you such traffic and SSL traffic that is become encryption, totally garbage data. But just to show you.

So, Cesar cyper, this is the key. This key is important. If that person resumé this text, they will put them here. But if they don’t know the key supposably put forth, it will become something else. But if they put two and decrypt them so they will get hello. This is called encryption and encryption. And the key which I use this is and the method which I use shift to key of this is called algorithm encryption algorithm, which method I use.

So, I will tell to my friend they just shift the words to two worlds away and you will get the original text.

So, this is called encryption algorithm. Okay, and so this is my encryption algorithm and why this plain text, when I change them to this becomes hypertext and key is one or two or three, whatever, and there is encryption, decryption. This the method we apply and the other person will put aside protests. They will apply to make them plaintext and they will use the same key to decrypt them. It’s the simple words to understand. Now with encryption and encryption. We have to type up encryption and encryption, symmetric encryption and asymmetric encryption. Encryption, we know when we change data from plain text to cyberattacks, we call them encryption. When we make data too hard, we call them encryption. We nobody know and change the data. We call them encryption. There are two possible way to make the data hard. One is symmetric and other is asymmetric.

So, what is symmetric? Symmetric encryption means to use the same key to encrypt in the same key to decrypt. What are you doing in this case? Two is the same key. When I was encrypting I used to when I was decrypting.

So, I use the same key.

So, this is called symmetric encryption. Same key is used for encryption and also the sankei is used for decryption.

So, this type of encryption, we call it symmetric encryption, like a key you can lock and you can unlock, you are using the same key to lock and unlock this. What we done here? Now, another method is asymmetric. And asymmetric. Another matter is asymmetric and asymmetric encryption, we are using two different key to encrypt and decrypt. You got my point, so there are two key to use. One key is to lock and the other key is to unlock. Let me quickly give you our demo. There is Krypto Tool. I’m not going in detail, I just want to give you an overview quickly. There is a utility which Carl Krypto tool, okay? And let me go to visit, there is encryption and encryption next, there is a classical method, classical metal, the Automator like a SESAR site, but in many go to so many encryption method. I don’t want to go in detail, but there is a modern as well. Let me use modern and modern. We have symmetric. We are only one key you can see it in here is very key. And there are two key keys. Nothing but just hexadecimal number. By the way, don’t confuse the key with. Okay, so let me choose a symmetric encryption first.

So, I choose. There are so many example of symmetric. Let me choose the first one. Okay, encryption and the key says this one and this thicky discothèque. By the way, Sukhi is this one.

So, let me drive this to Key and let me dad, though. Hello, everyone. This is my clear text message. Now let me encrypt them. This the you can understand anything, no, no, this is actual encryption and encryption garbage data. Look at nobody know that this is. Hello, everyone. Now, when the person did this one, they will give this garbage data, but they have to use the same method, which is eight years next. And here they will decrypt this time, okay? And here they will put it decrypted the message here, but they will use the same key if anything is wrong. And the key suppose if I change the key, suppose if. It will not decrypt look and nothing is coming out. I need to go back and I have to put the same key. This the key. The key which I encrypt, the same key has to be used to decrypt. And here you will see that is this the garbage data and this the actual message come out. This is called symmetric encryption. Same key. Now let’s do asymmetric. Let me do a visit. Encryption and decryption. Let me go to modern encryption and encryption. Let me go to asymmetric encryption and let me choose RSA. Now, they are asking so many things. First, they said generate two different key.

So, we need to go to Ghys RSA Key generator. Now they are telling me that these are the key M and E is the public and in and B is the private key.

So, m m e so this is in this Yawkey M and E this the E is the public.

So, let me write down this. The public. Probably key. Second, they said it and again, because mathematically they were combination, something similar, and this one would be this is public, which is totally different from the EBOW.

So, this is I’m sorry, private property is always private. It will not be visible and public will be visible all the time to everyone.

So, anybody can encrypt the message using this key and you will receive them and you will it like a box. You know, if this is an open box, this is a public key. But when you close this box so you don’t have a key, it will lock only the person held the key and open this box. Put your message in this public key and close them. Now, only the person will belong this public. You can open it now. Maybe in your mind that if this box is a fake box. Yes.

So, there is a certificate and many things coming in the picture. But I don’t want to go in detail. I’m just giving you a picture of you not going in any detail.

So, now my keys are generated. Let me go back now. Let me encrypt.

So, encrypt will use this. You will get public key and the group will use these private key.

So, now it’s asking me use the public key to encrypt the message.

So, I said this, the public key and the other one is the one part. This is ProPublica and this the message. Hello, everyone. Next, and this is cyberattacks, which I get I told you what is cyber attacks? So. cipherText, just this one, and if you need, the player takes.

So, clearly, this was a hello, everyone. That’s it, no regard the cybercafes. Now, what about the other party, the other party, what they will do when they receive the message, they will use the Krepp, they will use the same method, but here they will not use this key to decrypt them. They will use their own private key. They see private key and the second part of private key. And here they will use their garbage data. This one site predicts they will put them there. And next, they will get original text now. Hello, everyone.

So, this is Carl Semiotic and Osada asymmetric encryption semiotic was using same key to encrypt and decrypt and assemble to use two different key, which I show you quickly. Another concept is a hash. What is hash? We call them digest, we can call them chicks, some, we can call them message digest, we can call them hash, you basically hash is one way. It’s not like encryption and encryption. If you generate them once, it will be generated. And that’s it. We are using hash to, you know, that nobody checking their data in motion. Maybe your data is encrypted, but somebody ordered some more encrypted data.

So, what happen? You will assume more data even though it’s encrypted. He cannot read, the person cannot read. But they changed the algorithm. They changed them.

So, far, this proposed we are using hash algorithm, which are two famous one before messages and secure the hash algorithm. These are the two famous hashing algorithm. How let me show you this. My text. Okay, let me save this file. I want to send you this file, ABC on the desktop. I grab the market, consider them. It’s encrypted. You want this one? This one is encrypted. Yeah, this is encrypted. Nobody no. Underway this encrypted under the let me remove this one is right now you know, nobody know this is encrypted data but on the.

So, what I need the somebody can change them and it’d be something you don’t know but he make them more so you will you change data. You only encrypted, but he can change them.

So, for this purpose we need a hash algorithm. What I will do from here, I will generate hash of this with you before sending the data. There is my file, which was ABC. It is ABC, okay, and this one and I will calculate hash. Really, this is a five page. It’s one time. You know, it cannot be reversible. It’s not reversible. This is just for verification purposes. This thing has really regenerated before sending the file with ABC Dirtbag’s. Now I will worship you this the hash value when you resew when in default there is another application. When you receive ABC, what you will do, you will open them. ABC, it will generate some hash with you and now you will copy and paste the hash. Really, which I use and verify this not match. Why it has to be made by the way. Okay, let me do maybe I would under fire, okay? Sorry, it was a hit you make was okay.

So, let me click ABC now this is ABC and colourfully.

So, this the radio control me, okay, this thing.

So, when you receive them, you will generate and the one which I send you will make and verify if it is made. It means everything is okay. You receive the same data which I send. But if somebody Giang only one dard. Okay, I’m just putting one dart and control is. Now, when you receive the foreign ABC and the actual letter, which is Senate match, it means somebody after the letter.

So, for this purpose, we are using hash and there are two famous hash, which is a modified message that just five inch secured hash algorithm sure has many flavor. Let me go quickly.

So, this is a modified message. Just one, two, three, four, five. This is a message that just five is generated equally, 32 digits all the time. It will be like a small video, this one, which has many flavor to show, one, two, fifty six, three, eight, four, five and so on. And I assure you, as well, there is another concern to make his message authentication code, you can put extra password, as well extra password, ABC through the hash, really original plus key.

So, it will generate a new key. This is just extra protection. Nothing is end of the day just to use for which purpose to identify the data. The data is not being changed. When I sent and when you receive it, that’s it.

So, these are the two main thing which I greatly revised. Now, let me close this one quickly.