This project contains 4 methods i.e. encrypt() , decrypt() , calmodInv() , and main(). Uses of each method is given below.

<----------------------------Encryption part---------------------------------->

i) First we take two inputs i.e. multiplicative key and additive key , then we initialize a string named chiptext ii) We make three arrays named array , chiparray and index, array stores alphabet in small case and chiparray contains alphabet in uppercase and index contains integer elements. iii) We run our first for loop from i = 0 to i = array.length then we run our second for loop from j = 0 to j = input message's length, now if message's character matches with elements in array named array then we perform a calculation and put the output in array named index. iv) Then we make another for loop outside the previous loop , and run it from j = 0 to j = index.length , then we make a string out of it by taking the help to chiparray for example chiptext = chiptext + Character.toString(chipArray[index[j]]) ; v) Then we return the encrypted message.

<---------------------------------calmodInv------------------------------------>

i) Calculated multiplicative inverse .

<----------------------------Dencryption part---------------------------------->

i) First we take two inputs i.e. multiplicative key and additive key , then we initialize a string named chiptext ii) We make three arrays named array , plainArray and index, plainArray stores alphabet in small case and array contains alphabet in uppercase and index contains integer elements. iii) We run our first for loop from i = 0 to i = input message's length then we run our second for loop from j = 0 to j = array.length, now if message's character matches with elements in array named array then we perform a calculation in another method "calmodInv()" and put the output in array named index. iv) Then we make another for loop outside the previous loop , and run it from j = 0 to j = index.length , then we make a string out of it by taking the help to plainArray for example plainText = plainText + Character.toString(plainArray[index[j]]); v) Then we return the dencrypted message.

<------------------------------MAIN METHOD---------------------------------------->

i)main method takes choices for encryption or decryption and the message to be encrypted or decrypted then it cointains if else statements to direct the choices to respective method.

<-------------------------------------OUTPUT------------------------------------> <-----------------------------Encryption------------------->

Press 1 for ENCRYPTION , 2 for DECRYPTION : 1 Enter the message : hello

Enter multiplicative key : 7 Enter additive key : 2

ENCRYPTED message is : ZEBBW

<--------------------------Decryption------------------------>

Enter the message : ZEBBW

Enter multiplicative key : 7 Enter additive key : 2

DECRYPTED message is : hello