What do you have to do$?$

You are given a number of files to use as outlined below:

$-$ PublicKeyEncryption.java: This is a complete class that you cannot modify. It contains the

basics to use Asymmetric Key Encryption.

$-$ SimpleAsymKeyEncryptApp.java: This is $*$mostly$*$ a complete class. You will need to add

code and modify existing code as outlined below in steps $1-11.$

$-$ MasterPrivateKey.key: This is a private key that was generated along with it$$s public key

equivalent. The public key was used to encrypted the next file...

$-$ Encrypted.bin: This file contains encrypted text. The key in the file MasterPrivateKey.key

will decrypt it$.$

Changed you need to implement:

$1.$ Convert the for loop in private static String getTextFileAsString$()$ method to a while loop. Make

sure to comment the method as well.

$2.$ Surround the long if$/$else structure in main method with a do$/$while loop, such that the program

will only end when the user enters in the value $8$ as a choice.

$3.$ Convert the long if$/$else structure to a switch$/$case$.$ Also take care of the scenario where the user

does not enter a valid choice $(1-8).$ Tell them they made an invalid choice. Hint: look up the

default keyword.

$4.$ For choices $1$ through $7...$ slightly modify the code to allow the user to choose the names of the

files $($instead of them being hardcoded$).$ Hint, use an instance of Scanner to get the users

response, and store their answer in a String.

$5.$ Change choice $7$ so the decrypted text is written to a text file $($of the user$$s choice$)$ instead of

the console $($Hint: replace System.out with an instance of PrintWriter... don$$t forget to close it

either!$)$

$6.$ Test the program. Create a text file $($either with notepad or Eclipse$)$ and put a message in it $($less

than $117$ characters$).$ Run the program, choose $4$ and encrypt the text file.

Immediately choose $5.$ See if the decrypted text file matches the original text files$$ message.

$7.$ Choose options $1$ and $2$ to save the current pair of public and private keys to text files.

$8.$ Choose $8$ to quit.

$9.$ Rerun the program.

$10.$ Use the private key provided to you MasterPrivateKey.key on myCourses with choice $7.$ Use the

file Encrypted.bin from myCourses as the encrypted file to decrypt here. The resulting file, if all

works properly, will contain a message in English.

$11.$ Rerun the program again a few times, choosing option $4$ to encrypt a new text file with varying

amounts of text. Be sure to save the encrypted files with different names.

$12.$ Answer the following questions in the comments at the top of your code

$($SimpleAsymKeyEncryptApp$.$java$)$

a$.$ For each of the encrypted files you created, what can you note about the file size? $($right

click on the file and choose properties$).$

b$.$ Does it seem like the amount of text you encrypted seemed to have an impact on the

encrypted file$$s size?

c$.$ Does the size seem to relate to the limitation of the number of characters in the textfile

$(117)?$

d$.$ If we can$$t go above $117$ characters to encrypt, but we have more than $117$ to encrypt,

what would be a simple solution to fix this? $($Hint: If you have to ship a large item, but

that item is bigger than the biggest single box allowed to ship it$,$ what can you do to the

item to ship it and make sure it all makes it there in the end?$)$

$13.$ Done? Demonstrate the program to the TA$.$ Be sure to show the decrypted message from step

$10$ as well.

$14.$ Submit the following files to myCourses.

a$.$ PublicKeyEncryption.java

b$.$ SimpleAsymKeyEncryption.java

c$.$ The text file you created with some message in step $6.$

d$.$ The encrypted file created by the program in step $6.$

e$.$ The private key file from step $7.$

f$.$ The public key file from step $7.$ import java.util.$*$;

import java.io$.*$;

import java.security.$*$;

public class SimpleAsymKeyEncryptApp $\{$

public static void main$($String$[]$ args$)\{$

$//$Other implementations other than RSA do not work without messing with Eclipse's settings

PublicKeyEncryption pke$1=$ new PublicKeyEncryption$($PublicKeyEncryption$.$AlgorithmTypes.RSA$)$;

$//$Keyboard input.

Scanner kbInput $=$ new Scanner$($System$.$in$)$;

$//$Used to get the users choice from the

int choice;

String bufferData;

byte encryptedData$[],$ decryptedData$[]$;

PublicKey publicK;

PrivateKey privateK;

System.out.println$("=======================================================")$;

System.out.println$("$Welcome to the Simple Asymmetric Key Encryption Program"$)$;

System.out.println$("=======================================================")$;

System.out.println$("$Please choose from the following options:"$)$;

System.out.println$("1.$ Save my public key to a binary file."$)$;

System.out.println$("2.$ Save my private key to a binary file."$)$;

System.out.println$("3.$ Generate a new set of my keys."$)$;

System.out.println$("4.$ Encrypt using my key"$)$;

System.out.println$("5.$ Decrypt using my key"$)$;

System.out.println$("6.$ Encrypt using a key from a file"$)$;

System.out.println$("7.$ Decrypt using a key from a file"$)$;

System.out.println$("8.$ Quit the program