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Now, let's see another option in all of I forget, that is a definition which is encrypted messages

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to decrypt messages.

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So now, because the decryption and encryption code is mostly the same, will create to wrapper functions

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that this one is able to encrypt.

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Messages still function.

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Another is over.

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Decrypt messages and for the function that is of a translated message which we are going to use or which

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will hold the actual code to encrypt.

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So over here we are just calling that particular method or call it a method transfer.

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Was it instead understanding the value which has been returned by the particular method?

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So the translated messages still function versus the encrypted or decrypted string one character at

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a time and the list in translated are stored these characters so they can be joined when the string

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building is done.

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So if we come to the translated messages, start them moment we have here the blank string and the string

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Asgeir, which is we are converting it to the uppercase value.

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So keep in mind that Evgenia for this just this is a cipher, except a different key is used depending

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on the position of the letter in the message.

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So the key IDEX variable which keeps track of which suppy to use, starts at zero by default because

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the letter used to encrypt decrypt the first character of the messages steer the index zettl.

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So the program assumes that the key is in all uppercase letters to make sure the key is valid.

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So we call the function there and the rest of the code.

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In the translated message, Asgeir is similar to your Caesar cipher.

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So we are sitting here for a while and the message is still voted.

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No one is equal to the letter tested or to find and convert it to Apple check.

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If no one is not equal to one, then you check.

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If it is equal to encrypt, then find it and appended to the given letters.

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Similarly, if it is decrypt, subtract the value from the letter Oresteia and at the end then we are

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seeing it do more and add value to the letter.

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So after the for loop it sets the characters in the message to the variable SVM that the symbol on each

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iteration of the loop and it finds the index of the uppercase version of Cimolino letters now, which

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is how we translate a letter into one number.

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So if no one isn't set to minus one, the uppercase symbol was found in the letters.

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This still meaning that symbol is a particular letter and the key variable keeps track of which subcu

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to use.

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And the is always what Yawkey of the index of evaluates to.

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So of course this is just a single letter string.

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We need to find this letters index in the letters as to how to convert this up to an individual.

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And this individual is then added if encrypted encrypting in symbols number or subtracted is grappling

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with this enormous number.

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And in the seas, I reject whether the new value of the number was less than zero, in which case we

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added then the length of letters is still to it, or whether the new value of number one was the length

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of letters is still greater in which we subtracted the value from it.

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So these check handles the wraparound cases.

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However, there is a simpler way to handle both of these cases.

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If we more the integer stored in the number one by the length of the letter this year, we can accomplish

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the same calculation in a single line of code.

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Hence we have done this over here saying no more is equal to length of letters this year.

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For example, see if numbers minus eight we would want to add twenty six.

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That is the length of the start to get B and that can be expressed as minus eight modulo twenty six

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which evaluates to eighty or if numbers thirty one we would want to subtract twenty six to get five

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and thirty one modulo twenty six evaluates to five new modular arithmetic hander's voted up or down

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cases.

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The encrypted order, the decrypted character exist in the letters as the index of number.

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However, if we want the encrypted or the decrypted characters case to match the original case of symbol,

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hence we are checking over here.

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If symbol that is converted to uppercase and appended if it is in law, then converted to lowercase

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and then.

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So if the symbol is in an uppercase, then if the condition is true, it upends the letters of the characters

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at letters index number to the translated Asgeir because all the characters are already in uppercase.

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However, if the symbolism, the lowercase letter, the condition is true instead in the next line it

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up in the lowercase form of the letters at the index number two translated is.

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So this is how the encrypted all the decrypted message match the original message, now that we have

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translated this email, we want to ensure that on the next iteration of the loop, we use the next subject.

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Hence, we increment the key idea by one in the next line over here thinking X plus is equal to one

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click here.

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If the key idea is equal to the left of is make it again zero.

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So how about if we vote on the last supporting the give X then the key.

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All the GST are the X would be equal to the length of the USDA, hence this check condition and we the

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it back to zero if that's the case, so that the key to the index of X points back to the first subcu.

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Now after this, if we see here, the indentation indicates that the statement is spelled with the if

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statement which just started in the for loop after something no one is equal to let Orestiada fine.

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So here the code executes if the symbol was not found in the letters.

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Now this happens if symbolism no other punctuation mark like say a number, anything like six, seven

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something or a punctuation say like a question mark or something like that.

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So in that case, it upends the unmodified symbol directly to the translator SDR variable.

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So now that we are done building a string and translated Asgeir, we call the joint letter here on the

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blank string.

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So this line makes the functions work on the whole encrypted order, decrypted message when the function

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is called.

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Hence after this we just see the lines that cause the main function of the program was run by itself

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rather than by being imported by another program that wants to use its encrypt message or decrypt messages

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to functions.

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So with this, we have understood how the particular Virginia cipher demo executes and what is the core

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meaning that we have already written.

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So let's continue with the next part or the next session in this advanced course.

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That is our frequency analysis in this frequency analysis.

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You will learn how to determine the frequency of each English letter in a particular text.

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You will then compare this frequency to the frequencies of your ciphertext to get information about

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the original plaintext, which will help you break the encryption.