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Hey guys.

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Welcome back to another class of our course about Python.

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So until now we saw many many interesting things about Python how to use it.

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We talked about loops and everything but since we are still talking about loops I decided to create

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a small app with you guys where we will practice our for loop together as well as our first statement.

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And you guys we'll see what you can do with all this.

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And at the same time we're going to create some fun stuff.

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So very simple what I decided to create today is that well for example when there are communications

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on what's up or let's say telegram or whatever app what's happening is that those communications are

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encrypted.

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So I decided to do is create a cryptic engine to be able to cripple lets say conversations.

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So what we'll do today as they explain we'll do our scripting engine.

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So this engine will simply crypt let's say all the words that we'll write down so let's say write down

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a word.

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So this engine will crypt our word.

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So let's start.

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So very simple.

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What we want to do right now we want to.

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Well let me just explain exactly how this will work.

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So our scripting engine will equipped each letter by a number.

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So let's say for example have a letter a letter B literacy and each letter will have a number or a certain

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symbol and our user will write down a sentence where the password and our scripting engine will just

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grip everything.

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So let's start.

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So the first thing I'll ask you guys to do is write down a function so to write down to start the function

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we need to write down def and give a name to this function.

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So in this case the name of our function will be for example let's say crip crip cryptic encrypted.

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That sounds cool.

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All right.

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So open up our parentheses and what exactly our user will crypt.

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So he will crisp the sentence or a word you can write down sentences and write don't wear whatever you

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want.

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And two points.

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All right.

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So here starts our encryption.

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So we'll have an encryption and for now encryption will put nothing.

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So you understand later why we need an encryption.

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All right.

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So right now how this will work.

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It's very simple.

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We need to start with our for loop.

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So in this case for every element in sentence because once again we need each element it could be for

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every letter it could be for every whatever you want.

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But in our sentence we'll have well when our user will enter a sentence there will be a letter for it.

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So let's say you will he will say let's eat.

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He says just hello.

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So for every element and hello or for every letter and Hello we are looking to change one letter by

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one number.

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So let's say for example for every element in our sentence.

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So once again you need to use the same words here.

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So sentence here and sentence there

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what I want to do.

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So I want Python to verify if the element is equal to a.

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So in this case if the element is a because we will change our letter a first so we'll write down if

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element in a.

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So what does this mean.

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Let me explain.

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So the logic is very simple here we have our sentence that the user will enter we want Python to verify

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for each element in our sentence.

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If this element is in a.

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So if there is an A a big eight or small eight in our element we can put them together.

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So it doesn't really matter because Python or if there is this letter or this letter in our sentence

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then if there is a letter what we want to do we simply want to add our encryption.

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So in this case is going to.

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Encryption will be equal to encryption plus one.

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All right.

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So what does this mean.

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Our encryption for now is equal to zero what we want to do by writing encryption equals encryption plus

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one.

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This means we'll add one here and then this case will change our a by 1.

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So this is what all this means.

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So this is a good way to change our first letter by year well by one because you can see it's very very

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well it's very simple in this case let's say.

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Translation here it's gonna be way easier for you to understand

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all right.

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So right now we got everything next thing that we want to want to do the exact same thing for each letter

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of the alphabet.

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So for the letter B letter C letter D and the other letters.

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So how exactly we do this.

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Very simple.

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We simply copy the if statement right here so we can copy it and we passed it down there.

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And instead of the letter A we will use the letter B but it's very important since we are working with

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a if statement that is in another if statement.

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We'll use the Elif

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because once again we're working with a if statement and if statement that is another if statement great.

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And not forget change or one by two.

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So what you understand from here right there what we have.

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So Def scripted sentence so right here for each element in our sentence we will change will will we

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ask Python to look for each element in our sentence if our element is equal to a we want to add one

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to our element.

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So instead of having let's say a want our eight to become one.

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So this is what what this means then when this part is done one to verify the exact same thing for the

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letter B and then it's going to be if we have a b wanted if we want to change our B by the letter to.

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So this is the first part of our or the first part of our translation where our encryption.

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So the next thing that we want to do want to do this for each and every letter that we have.

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So simply copy our let's say we take our elif statement here and the best in there and instead of writing

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it it's going to become C. and instead of two here it's gonna become three.

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As you can see it's very easy.

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I want to ask you guys to do right now is simply do the exact same thing for all the letters of the

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alphabet.

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So at the end they should give you something that looks like this as you can see I have all my letters

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here and each of my letters is trans.

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What each of my letters is replaced by a symbol.

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All right.

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If in the case that all this is not respected what one might done to return.

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Well it's very simple.

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We want Python to return translation plus element.

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So in this case translate to a translation Translation so is equal to nothing and plus element

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will be equal.

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And then we return.

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Translation

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great.

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So as you can see right here what we can understand here is that each letter of our alphabet will be

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changed by a number so in this case let's say for example the letter A will be changed by one letter

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B will be changed by two letter C will be changed by G.

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So this is the goal of our operator here.

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Right now we want to print exactly so it's very simple.

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We want to ask our user to print.

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We will ask our user to write down a sentence a sentence or a password or whatever and this password

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will be cryptic.

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So how do we ask our user to print something very simple.

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We'll use our print function and write down our cryptic so the name of our our function here is cryptic

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so we write down print will print cryptic but inside our encrypted we want to ask our user to write

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down a sentence.

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So how exactly we ask.

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We ask our user to write down a sentence we will use our input function.

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So I don't input and in this case we'll ask our user to write down the sentence will tell him what do

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you want to script.

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Great.

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So here here is our function so you can see we have our function right here that we created.

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Our function is named cryptic our function changes letters by numbers or symbols.

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And here we ask a python to print our function in which we'll write down we'll ask our user to write

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down a sentence.

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So if we run our code to see what it looks like and our code ask us What do you want to quit.

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So let's say I want a script.

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Hello my name is someone as you can see here it is.

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It's our encryption we can write down anything we want.

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Let's say for example Hello.

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I love pizza as you can see all the symbols are not cryptic.

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Since we didn't define an encryption for our symbols but if you guys wanted to find encryption for your

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symbols well you can do it as well so you can see here we have everything that we ask by thumb to encrypt

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is encrypted 2 8 5 b is H.

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So if we verify on our code right here h e so 8 5.

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All right.

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So I hope you guys understand what I'll ask you right now to do to practice everything that we just

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saw.

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Well you have your equipment encryption so have your encryption.

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I think your encryption software right now it's something very basic.

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But once again you have it right then what I'll ask your guest to do is try once again just to practice

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tried to create an decryption decryption software.

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So once again you have your encryption there and you want to decrypt your code.

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So let's say you want to decrypt all this.

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What you what you just wrote it means hello.

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I love pizza so try to do a reverse engineering reverse engineering and try to go from this to this

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right here.

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So simply recreate another software like this and try to go from this encryption to back to the normal

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word to the normal word.

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So that's it for this class guys.

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Right now you know how everything works.

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We created our small project and see all in our next class.