Java encryption program 🔑

Java substitution encryption tutorial

IMPORTANT NOTE: I don't know much about encryption. I attempted to write this encryption program by popular request. This is a substitution cipher and not a OTP. My bad

#java #encryption #tutorial

[BroCodez]

IMPORTANT NOTE: This is a substitution cipher and not OTP. My bad

public class Main {

public static void main(String[] args) {

EncryptionProgram ep = new EncryptionProgram();

}

}

import java.util.*;

public class EncryptionProgram {

private Scanner scanner;
private Random random;
private ArrayList<Character> list;
private ArrayList<Character> shuffledList;
private char character;
private String line;
private char[] letters;

EncryptionProgram(){
scanner = new Scanner(System.in);
random = new Random();
list = new ArrayList();
shuffledList = new ArrayList();
character = ' ';

newKey();
askQuestion();
}
private void askQuestion(){
while(true) {

System.out.println("What do you want to do?");
System.out.println("(N)ewKey, (G)etKey, (E)ncrypt, (D)ecrypt, (Q)uit");
char response =

switch(response) {
case 'N':
newKey();
break;
case 'G':
getKey();
break;
case 'E':
encrypt();
break;
case 'D':
decrypt();
break;
case 'Q':
quit();
break;
default:
System.out.println("Not a valid answer :(");
}
}
}
private void newKey(){

character = ' ';
list.clear();
shuffledList.clear();

for(int i=32;i<127;i++) {

character++;
}

shuffledList = new ArrayList(list);

System.out.println("*A new key has been generated*");

}
private void getKey(){
System.out.println("Key: ");
for(Character x : list) {
System.out.print(x);
}
System.out.println();
for(Character x : shuffledList) {
System.out.print(x);
}
System.out.println();
}
private void encrypt(){
System.out.println("Enter a message to be encrypted: ");
String message = scanner.nextLine();

letters = message.toCharArray();

for(int i =0;i<letters.length;i++) {

for(int j =0;j<list.size();j++) {
{


}
}
}
");
for(char x : letters) {
System.out.print(x);
}
System.out.println();
}
private void decrypt(){
System.out.println("Enter a message to be decrypted: ");
String message = scanner.nextLine();

letters = message.toCharArray();

for(int i =0;i<letters.length;i++) {

for(int j =0;j<shuffledList.size();j++) {
{


}
}
}
");
for(char x : letters) {
System.out.print(x);
}
System.out.println();
}
private void quit(){
System.out.println("Thank you, have a nice day bro!");
System.exit(0);
}
}

[riseofkingdoms]

Easily the best teacher I've come across for teaching programming! I'm not quite a beginner but my knowledge was pretty disorganized and scattered, your videos help me a great deal! thank you! keep up the awesome work Bro!!!!

[winterSweet-km]

just found this channel by accident, subscribed without a hesitation. keep up with the UNIQUE and WHOLESOME work man!

[radusimonica]

Ideea: add two new methods:
saveKey() and setKey().
Save the key to a file and then reload that key from the file.

So, two way encrypted communication based on a common key file.

Ofcourse that key file can be encrypted with a known variable (like a password). Just shifted a few chars. That way even if someone has the keyfile, still needs to unshift the key in order to work.

[stephaniepanah]

Strains of, Car car equals new car, and, Dog dog equals new dog, keep rolling through my head. good job. thank you

[DanielSmith-ujrr]

Awesome. Thank you Bro! This project is very useful. The way you teach is just AWESOME!

[maxwong]

I find it inconvenient as the all the data is clear when I terminate the program .

I want to restore the previous data when I start over the program .

I recall that you have taught me how save object's information and reload it by using serialization and deserialization .

I think it's a good practice and challenge for me to combine the encryption, serialization and deserialization together .

Here's my code .

Class : UserInfo

import java.io.Serializable;
import java.util.ArrayList;

public class UserInfo implements Serializable {

private static final long serialVersionUID = 1L;

ArrayList<Character> list ;
ArrayList<Character> shuffledList ;
String userMessage, encryptedUserMessage ;
}

Class : EncryptionProgram

import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

import java.io.* ;

public class EncryptionProgram {

transient private Scanner scanner ;
private ArrayList<Character> list ;
private ArrayList<Character> shuffledList ; // shuffled(洗牌的)
private char character ;
private char[] letterArray ;
private String userMessage, encryptedUserMessage ;

EncryptionProgram() throws ClassNotFoundException, IOException {

scanner = new Scanner(System.in);
list = new ArrayList<>() ;
shuffledList = new ArrayList<>() ;
character = ' ' ; // ASCII values of [space] = 32

askQuestion() ;
}

private void askQuestion() throws ClassNotFoundException, IOException {

while (true) {
;
System.out.println("What do you want to do ?") ;
, (N)ewKey], (G)etKey, (E)ncrypt, (D)ecrypt, (M)essage, (Q)uit") ;
char responseChar = ;

switch (responseChar) {
'L' :
;
;
'N' :
;
;
'G' :
;
;
'E' :
;
;
'D' :
;
;
'M' :
;
;
'Q' :
;
;
:
a valid answer .") ;
;
}
}
}

// generate new key .
private void newKey() {
// reset the character to 32 .
character = ' ' ; // ASCII values of [space] = 32
list.clear() ;
shuffledList.clear() ;
encryptedUserMessage = "" ;

// ASCII decimal (32-126), 32 = [space], 127 = [DEL] ;
for (int i = 32 ; i < 127 ; i++ ) {
;
}

shuffledList = new ArrayList<>(list) ;
;
System.out.println("A new key has been generated .") ;
}

// retrieve the key .
private void getKey() {
System.out.println("Key : ") ;
for(Character x : list) {
System.out.print(x) ;
}
System.out.println() ;
key : ") ;
for(Character x : shuffledList) {
System.out.print(x) ;
}
System.out.println() ;
}

// encrypt the message .
private void encrypt() {
System.out.println("Please send a a message for encryption :") ;
String message = scanner.nextLine() ;
userMessage = message ;
encryptedUserMessage = "" ; // it will = null if no initialization .
letterArray = message.toCharArray() ;

int i = 0 ;
for (char x : letterArray) {
letterArray[i++] = ;
encryptedUserMessage += ;
}

;
}

// decrypt the message .
private void decrypt() {
System.out.println("Please send a a message for decryption :") ;
String message = scanner.nextLine() ;
letterArray = message.toCharArray() ;

int i = 0 ;
for (char x : letterArray) {
letterArray[i++] = ;
}

;
}

private void message() {
System.out.printf("Your message before encryption : \"%s\"\n", userMessage) ;
System.out.printf("Your message after encryption : \"%s\"\n", encryptedUserMessage) ;
}

private void load() throws IOException, ClassNotFoundException {
UserInfo userInfo = null ;

// create a file to store you object'sinformation .
FileInputStream fileIn = new ;
ObjectInputStream objectIn = new ObjectInputStream(fileIn) ;
// User class is not recorded in file so we need to cast it as the object type .
userInfo = (UserInfo) objectIn.readObject() ;

fileIn.close() ;
objectIn.close() ;

list = userInfo.list ;
shuffledList = userInfo.shuffledList ;
userMessage = userInfo.userMessage ;
encryptedUserMessage = userInfo.encryptedUserMessage ;
loaded .") ;
}

private void quit() throws IOException {

UserInfo userInfo = new UserInfo() ;
userInfo.list = list ;
userInfo.shuffledList = shuffledList ;
userInfo.userMessage = userMessage ;
= encryptedUserMessage ;

// create a file to store you object'sinformation .
FileOutputStream fileOut = new ;
ObjectOutputStream objectOut = new ObjectOutputStream(fileOut) ;
;

fileOut.close() ;
objectOut.close() ;

saved .") ;
System.out.println("See you next time .") ;
System.exit(9) ;
}
}

Class : Main

import java.io.IOException;

public class Main {

public static void main(String[] args) throws ClassNotFoundException, IOException {

EncryptionProgram ep = new EncryptionProgram() ;
}
}

[kxnyshk]

man! this was so cool and easy to learn! Thanks for this :) 💜

[dth]

Program complete. This walkthrough is golden. Thanks, Bro!

[TyyylerDurden]

I would use 2 shuffled lists and took from each by index in order. It would allow to avoid double letters.

[Ahmed_TheProgramer]

7:27 🤔Why we declared "random" and initialized but didn't use it ?

[meksudbuser]

Bro!, You are amazing, I just wanna say Thank you.

[Ahmed_TheProgramer]

for encrypt method I think it will be better if we wrote it like this:

private void encrypt(){

System.out.print("\nEnter a message to be encrypted :");

line = scanner.next();
int lineLength = line.length();
this.letters = new char[lineLength];

for(int i = 0; i < lineLength; i++)
letters[i] = shuffledList.get( list.indexOf( line.charAt(i) ) );

System.out.println("Your encrypted message is :" + String.copyValueOf(letters));

}

[maxwong]

I find another quicker way to encrypt the message instead of nested loop .

I use the listName.indexOf(element) .
// You can use it with an non-primitive array by changing it to list first .
//

private void encrypt() {
System.out.println("Please send a a message for encryption :") ;
String message = scanner.nextLine() ;
letterArray = message.toCharArray() ;

int i = 0 ;
for (char x : letterArray) {
letterArray[i++] = ;
}


; // array cannot be print directly as only string representation will be shown, except char array .
}

[Geno]

my bro, thanks for this java tutorial <3;

[ΒαγγΣτανιος]

Nice tutorial but this is not One-time pad encryption. This is a simple replacement encryption and can be cracked with the proper program and a sufficient large message.

[jordanguada]

thanks man, gonna use this skill for my upcoming internship!

[roryodonoghue]

Excellent. Learned a lot. Thank You, Sir

[rodelioliwag]

Thank you. This helps a lot. Am a beginner at this

[McMeil]

so easy and so necessery)
very usefull, thnx