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Welcome to the first session in our Biton hacking beginner level class.

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Now, in this particular course, the first topic that we will be covering is the revolt.

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So now we need to first understand.

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What do you mean, Modibo Saiful?

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It basically is encrypting any message by printing it in a reverse order.

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So, for example, if we see suppose.

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Hello.

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It should be printed as in a total reverse order.

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So the l r o w space o l l e h that is how it should be basically printed.

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OK, so it would be great to get the original message.

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You simply reverse the encrypted message again.

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You will get it in a decrypted form.

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Right.

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So encryption and encryption steps are the same, but now we will see one particular code for a reverse

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cipher program and then we will see what all things could be done in reverse cipher program that we

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would create.

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So first thing what we will do is let's just remove this.

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Now, basically, we are into Python, ideally, OK, which is basically an interface that you can type

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the programs.

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If you want to save it, you can create it in a new file, type the whole program, save it and you

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will run the particular program, which will give you the total output.

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So over here, we will start with C, a variable message that's equal to in single code.

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We can say this is Python.

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Hacking.

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Session one.

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We are doing.

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Reward's.

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Saiful, this basically we want to reverse it, so we are putting this fixed whatever text you want

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to make it in reverse order in a variable named message.

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Then we say here see translate it is equal to again open closed bracket.

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Then we say I is equal to we use the length method and here we put the variable that we have created

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minus we put it one because it should go to the length minus one.

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That is the last character of your message because here it starts with the index of zero.

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Then we say while I is more than equal to zero, calling in here to start the particular loop.

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So we will move here and will c c translated.

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That is the variable that we have now.

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That variable is equal to translate it, plus the value of message at the index of.

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OK, and then we see eye to eye, minus one now after this, we come to the next line and we say bring

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the value of.

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Translated, OK, now let us just save this, so for saving, it will go to file say save, let us say

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we didn't drive Biton hacking big enough and here we will give see the more one dot be white as the

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extensions for python fights.

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OK, and then you can simply press a fight if you want to run or you can go here and here.

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Also you can sit on modu so once you see it on module you can see whatever text we have written.

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Everything is coming in, the total rules of it.

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OK, now suppose you want to decrypt the text that we have already encrypted.

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So over here what we will do is we will copy it on this text.

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OK, so right.

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Click copy.

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OK then we will go back to our program.

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And over here now in this message, OK, in this line we will be OK.

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Now let's save this again and let us run the module again.

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So again, this is how we have encrypt decrypted.

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OK, so in the first program we have encrypted that in the same program.

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Just copy pasting the encrypted one in the message when we have decrypted.

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OK, so in this basically we we are making a short of a thing unlike we are hacking using Python by

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encrypting and decrypting it.

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OK, OK, so now let's go to the program back here and let's understand what have we done this over

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here in the light of the first one that is we have the message variable.

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So whatever text you want to encrypt or you want to decrypt as a new string, we have placed it inside

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the message variable and the translated variable is where our program is basically on the store, the

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horrible string.

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Right.

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So at the start of the program, the translated variable over here is blank.

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So it is having no string, it is just a single code Max and not the.

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So you don't mean that this is a single quotation now to find the length of a particular string we have

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used your the alien method, which is basically used for assignment statement, storing all value in

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the variable.

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I add that value is nothing but the length of the variable message.

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So the expression that is evaluated and stored in the variable length message minus one.

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The first part of this is a function that is lenth function and which accepts a string argument, just

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like we have this print which is accepting the message argument.

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OK, so when we create this particular variable, we get the integer value of how many characters are

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there in a particular string.

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That is for us it is in the message variable.

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OK, now we can also use this lens function in a very interactive shell, for example.

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Now let's just go here to the shell here and we write down just to lend and we say hello.

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For example, we get the Delinda's fif.

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We say, suppose let's just open close back.

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We don't give any fixed in between.

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So we get the length zero or we see a variable system is equal to.

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OK, then we say Lenn is equal to the variable SBM.

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OK, we get the let's do all we say in length variable.

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We open double quotes, we say hello one text, we let's give your a comma, then we add there all space,

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we concatenate that with the variable.

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OK, and we close it, so here we get Delinda's 30.

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OK, so from this particular return value, we know that the particular string that we have given in

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the bracket is having how many characters in a blank string will have a zero character.

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So if we store any value apart from a blank value, you will get exactly how many lenth you are storing

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in a particular given string in that function of length that we are using.

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So after this particular function that we have used, the next thing we run this loop here.

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OK, so we over here, we have given an instruction to Python.

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That of provided statement is basically made up of four parts.

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You can see the first is the real key word that we have.

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Then we have the condition that is I is more than equal to zero.

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Then we have a colon symbol after that and the block of code, which will execute if the condition is

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true, that is, you will pass the value of.

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OK, so here a condition is basically nothing but an expression which is used in your vital statements.

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And the block of code in the file statement will execute as long as the condition becomes true.

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So to understand why, we will need to first learn about booleans, comparison operators and blocks.

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So come in to the Boolean data type.

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Basically, Boolean has only two values, either true or false.

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Now this boolean values Audible's, we call our case sensitive.

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So you always need to capitalize the deal or if by leaving the rest in peace so they are not string

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value.

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So you don't put quotes around it true or false value.

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OK, now for example, if you want to try out something, we can say, for example, spam is equal to

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two.

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OK, now if you want to print the value of spam, we will get the value to or if you say spam is equal

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to Foote's again, you bring the value of spam.

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Now you get the value for it.

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Right.

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So like a value of any other data type voice can be also stored in the variables.