6.2 Symmetric Algorithms

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Hello, everybody. And welcome to the I achieve Security episode number 21 Symmetric algorithm. My name is Alejandro Pena, and I'll be instructed for today's session.

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The learning objectives is to understand and be able to identify the main concepts off symmetric algorithms.

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Well, we have again Bob and Alice here. They went well. Book Buck. When fra.

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So a tan salon. So done, Josh Him.

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So we have above here.

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And I was here,

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um,

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asymmetric algorithms.

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Well, she met Valerie was algorithms uses one key on Lee between the two parties or whatever quantity off people there is. So the same key, you know,

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two.

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Will you sit here and hear Now the main The main problem with this is how can we get the key from here from Bob to do Wallace?

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How can you know? How can we transfer the key safely if you know that right here.

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There we have the injury.

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The cloud,

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um you know,

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how can we be sure that the key whenever we transfer here wasn't intercepted here or here or here or in the number of hope hopes this, um, you know, jump

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this packet jumped. Uh, how can we know that it wasn't modifying. How can we know if it was stolen for someone? Because at the end, if there's a delicious guy

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over here,

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No, he's angry

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for some reason.

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Um,

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hey, stole the key.

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So any communication between Bob and Alleys will be, you know,

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decrypted by this guy because they he has the key. And, you know, there's a problem there talking. We make sure that we can raise this guy

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and it doesn't exist anymore.

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Uh, well,

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there's a problem that can be solved, and we'll see that with asymmetric case. But for now, this is the main problem. We can use our band,

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um,

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communications.

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We can send the key over a news, be or we can send the key, you know, printed in a letter. I don't know any outer band communication that can work for us. It will be fine. The point is that this case should be only by buff and by Ali's. That's it.

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Okay, having said that, this this is one of the disadvantages of using cimento kiss. The other disadvantage of using symmetric kiss is that we have to use a lot of kiss The formula to calculate how many keys we need is this one

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and

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I don't reply by an mines one

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all of this divided by two.

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Now, the problem is that

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it is all good. You know, when we have only two people because we need to kiss right here. When I say to kiss, I mean the same keeper shirt between this person. Right? So this is even though it is the same key we needed at this side above side and analysis eyes.

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Um, So what? What will happen if we have a business with

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50 employees? S o old man will have to replace the formula and use it

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50 by 50 miners long to be 49 divided but to and the result for this is a 1000

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225.

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When you see the 225

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we need 1225 cases

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symmetric case. In order for this, 50 boys can communicate with encryption. So this is a This is an issue for us because at the end, the more employees the monkeys we need, this becomes unmanageable. If we have 100

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employees and can you imagine 1000 boys. This will be a you know, a headache for Franny Syst system administrator.

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These are two main decent badges off using symmetric case. But you know, it is all the lust. What what's one of the advantages of using is that they are really fast. This symmetric hey Kiss has better

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performance

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than the a C. Merrick asymmetric kiss. This'd advantage that America symmetric kiss has

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over asymmetric key. So to summarize to two made these advantages. You know, how can we distribute the kids securely over the Internet? And how many kids do we need to communicate

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in the advantage that it has is the performance eating Crips and decreased the decrypt way faster? Because the key sizes are,

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uh,

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you know,

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how can put this Even though the key sizes are

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short, let's say that because, uh,

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age metric is, has they all these algorithms uses a larger key than they seem metric algorithms. They still are secured asymmetric algorithms, for example. Yes,

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this is a geometric algorithm, and it's really, really fast. And what will happen wear,

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huh? 512 Children t Today equation, this algorithm becomes almost unbreakable.

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The work factor to break this to break this hour through this is, like

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1000 millions of years. So,

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um, you know the performance. I's good. The problem is that how can we distribute this among, um,

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the employees are the users. And you know, how many kids do we need? S O. What are these? Mary algorithms? Well, symmetric algorithms in both a s as well, right? Said,

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um,

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this is the most popular I believe it comes from 128 256 and 512. Things is the most common numbers. You know, all them multiple of eight.

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Um, then we have, um,

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Harrison Ford,

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45

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our six.

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Uh oh. This also symmetric when it's asymmetric again, is that the same key has to be used at both sides of the communication. Um,

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we can also mention the two feet tall fish or two fish. The serpent, the Blowfish.

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I mean, write it right here

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so that you can have it

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to fish the blowfish.

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Um, you know,

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the E e s

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triple this,

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which right away all for example, RC for, um

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uh, this and Tripolis are all you know, defecated. We cannot use it. That anymore because they're broken. Actually, RC four was the one used in the weapon authentication off the off the rotors and the wireless.

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How many symmetric kids are needed in a business with a 755 employees? Well, that's a tough one. Um, what would you do? The math. Remember that the formula for this

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it was actually, uh and,

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well, multiple labor, my and mine's one

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on this divided. But to So by using this formula, there is The result is 284,635 is a huge number.

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Yeah, that how many? If you have a business with more than 1000 employees, you can see that it becomes unmanageable.

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Was the bits based, advantage abusing symmetric case? Well, it has a better performance.

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Um, that's the best advantage. It has other batches, but I guess that's the main one

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name. And this is van. Touch of using symmetric is well, the number of kisses which, you know, was the first question becomes unmanageable. When way you go up to 20 employees or 20 users and the other one just completed. The the answer

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is that how can we distribute the key securely

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when we needed at both out. Its of the connection

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in today's reflector would talk about the main concept off symmetric Kiss

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Supplements materials again, the Phipps publication.