Please help me in C++ I just need help with my ceasar cipher and decipher function please help Caesar's Cipher is an algorithm that substitutes each letter of the alphabet by shifting the letterby a given key value. For example, a key of 3 would replace A with D, B with E, and so on. Asdescribed in https://www.youtube.com/watch?v=6-JjHa-qLPk, it is fairly easy to break anencrypted message if all letters are shifted by the same number. An improved approach is touse a multiple-digit key that would shift each letter in a document by a different amount. Thefollowing screenshot from the video shows how a 10-digit key 5182273847 can encrypt "FREEPIZZA IN THE CAFETERIA" into "KSMG RPCHE PS UPG EHIMXLWJI". The first letter F isshifted by 5 and replaced with K. The second letter R is shifted by 1 and replaced with S. Thethird letter E is shifted by 8 and replaced with M. And so on.Note that the video and the following screenshot from the video did not convert the last threeletters properly. The result should be "WJI" instead of "SJB".●IQKERLKSMGL T ΝΤΗMUOUOI+5 +1 +8 +2PNAFC NQ SNEQOBGD ORRPCHESQD 1 FTREJG+2 +7 +3 +8 +4●P SQRU+7 +5CFGKVJQHZDGHWKRE HII MIXILISF 1 J N YIMGJKOZNULWR+1 +8 +2 +2 +7 +3 +8 +4 +7+5 +1 +8O.●U P GQ HAs we know, a string is a sequence (array) of characters. The circular effect for this improvedCaesar's Cipher comes in two forms.●5182273847The first circular form applies to a string of digits as the key. In the above example, as wemove down the message, we move down the key string. That is, we use 5 as the key forencripting the first letter 'F', 1 as the key for encripting the second letter 'R', and so on. When weget to the 10th letter 'I', 7 is used as a key. After that, for the 11th letter 'N', we circle back to thebeginning of the key string and use '5' as the key to encript.The second circular form applies to a string of all alphabets.const string CaesarCipher::ALPHABET =When the "shifting" does not go past the last letter, no circular effect. For example,● If the letter to be encripted is F and the key is 5, the encripted letter would be K.• If the letter to be encripted is E and the key is 2, the encripted letter would be G.GHLWWhen the "shifting" go past the last letter, it circular back to the beginning of the alphabet. Forexample,LISIJIBMTKCIn this lab, you are asked to implement and test the Ciper and Decipher member functions ofthe Caesar Cipher class. We will focus on only the UPPERCASE LETTERS.string cipher (const string&) const;This function takes a string as its parameter and returns an encrypted string by repeatedlyapplying the appropriate shifting according to the key. For example, in the following codesegment, "CJVYB" would be returned by the cipher function.CaesarCipher demo("35");cout

Question

Please help me in C++ I just need help with my ceasar cipher and decipher function please help Caesar's Cipher is an algorithm that substitutes each letter of the alphabet by shifting the letterby a given key value. For example, a key of 3 would replace A with D, B with E, and so on. Asdescribed in https://www.youtube.com/watch?v=6-JjHa-qLPk, it is fairly easy to break anencrypted message if all letters are shifted by the same number. An improved approach is touse a multiple-digit key that would shift each letter in a document by a different amount. Thefollowing screenshot from the video shows how a 10-digit key 5182273847 can encrypt &#34;FREEPIZZA IN THE CAFETERIA&#34; into &#34;KSMG RPCHE PS UPG EHIMXLWJI&#34;. The first letter F isshifted by 5 and replaced with K. The second letter R is shifted by 1 and replaced with S. Thethird letter E is shifted by 8 and replaced with M. And so on.Note that the video and the following screenshot from the video did not convert the last threeletters properly. The result should be &#34;WJI&#34; instead of &#34;SJB&#34;.●IQKERLKSMGL T ΝΤΗMUOUOI+5 +1 +8 +2PNAFC NQ SNEQOBGD ORRPCHESQD 1 FTREJG+2 +7 +3 +8 +4●P SQRU+7 +5CFGKVJQHZDGHWKRE HII MIXILISF 1 J N YIMGJKOZNULWR+1 +8 +2 +2 +7 +3 +8 +4 +7+5 +1 +8O.●U P GQ HAs we know, a string is a sequence (array) of characters. The circular effect for this improvedCaesar's Cipher comes in two forms.●5182273847The first circular form applies to a string of digits as the key. In the above example, as wemove down the message, we move down the key string. That is, we use 5 as the key forencripting the first letter 'F', 1 as the key for encripting the second letter 'R', and so on. When weget to the 10th letter 'I', 7 is used as a key. After that, for the 11th letter 'N', we circle back to thebeginning of the key string and use '5' as the key to encript.The second circular form applies to a string of all alphabets.const string CaesarCipher::ALPHABET =When the &#34;shifting&#34; does not go past the last letter, no circular effect. For example,● If the letter to be encripted is F and the key is 5, the encripted letter would be K.• If the letter to be encripted is E and the key is 2, the encripted letter would be G.GHLWWhen the &#34;shifting&#34; go past the last letter, it circular back to the beginning of the alphabet. Forexample,LISIJIBMTKCIn this lab, you are asked to implement and test the Ciper and Decipher member functions ofthe Caesar Cipher class. We will focus on only the UPPERCASE LETTERS.string cipher (const string&) const;This function takes a string as its parameter and returns an encrypted string by repeatedlyapplying the appropriate shifting according to the key. For example, in the following codesegment, &#34;CJVYB&#34; would be returned by the cipher function.CaesarCipher demo(&#34;35&#34;);cout << demo.cipher(&#34;ZESTY&#34;) << endl;A&#34;ABCDEFGHIJKLMNOPQRSTUVWXYZ&#34;;If the letter to be encripted is T and the key is 7, the encripted letter would be A.If the letter to be encripted is Z and the key is 3, the encripted letter would be C.Z would be encripted into a letter in ALPHABET that is 3 spaces forward, which is C. Notethe circular effect of starting from the letter A in the shifting process.E would be encripted into by a letter in ALPHABET that is 5 spaces forward, which is J.S would be encripted into by a letter in ALPHABET that is 3 spaces forward, which is V.Note the circular effect of using 3 as the key after both 3 and 5 have been used.T would be encripted into by a letter in ALPHABET that is 5 spaces forward, which is Y. ●●●Z would be encripted into a letter in ALPHABET that is 3 spaces forward, which is C. Notethe circular effect of starting from the letter A in the shifting process.E would be encripted into by a letter in ALPHABET that is 5 spaces forward, which is J.S would be encripted into by a letter in ALPHABET that is 3 spaces forward, which is V.Note the circular effect of using 3 as the key after both 3 and 5 have been used.T would be encripted into by a letter in ALPHABET that is 5 spaces forward, which is Y.Y would be encripted into by a letter in ALPHABET that is 3 spaces forward, which is B.Note the keyword const in the function prototype, indicating that the function shall not changethe parameter string or the key__data member of the invoking function.It is important that your implementation takes advantage of the circular effect and allows O(1) asthe time complexity for encripting each letter.●string decipher (const string&) const;This function takes a string as its parameter and returns a decrypted string by repeatedlyapplying the appropriate reversed shifting according to the key.For example, demo.decipher(&#34;CJVYB&#34;) should return &#34;ZESTY&#34;.C would be decripted into a letter in ALPHABET that is 3 spaces backward, which is Z. Notethe circular effect of starting from the end of the alphabet once the description passes thefirst letter.J would be decripted into a letter in ALPHABET that is 5 spaces backward, which is E.V would be decripted into a letter in ALPHABET that is 3 spaces backward, which is S. Notethe circular effect of using 3 as the key after both 3 and 5 have been used.Y would be decripted into a letter in ALPHABET that is 5 spaces backward, which is T.B would be decripted into a letter in ALPHABET that is 3 spaces backward, which is Y.Note the keyword const in the function prototype, indicating that the function shall not changethe parameter string or the key_ data member of the invoking function.It is important that your implementation takes advantage of the circular effect and allows O(1) asthe time complexity for decripting each letter.Here's a sample output demonstrating the testing of the cipher and decipher functions.What is your message:THE QUICK BROWN FOX JUMPS OVER THE LAZY DOGWhat is your key (digits only)? _1_Encrpted to:UIF RVJDL CSPXO GPY KVNQT PWFS UIF MBAZ EPHDecrypted back to:THE QUICK BROWN FOX JUMPS OVER THE LAZY DOGTry another key? (Y/N) YWhat is your message:FREE PIZZA IN THE CAFETERIAWhat is your key (digits only)? 5182273847Encrpted to:KSMG RPCHE PS UPG EHIMXLWJIDecrypted back to:FREE PIZZA IN THE CAFETERIATry another key? (Y/N) YWhat is your message:ZESTYWhat is your key (digits only)?_35Encrpted to:CJVYBDecrypted back to:ZESTY

Accepted Answer

As per the given information, we need to implement cipher() and decipher() methods of CaesarCipher…