Cryptography : Caesar Cipher

Cryptography : Caesar Cipher

  1:12 PM    mayuravaani

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Caesar Cipher

Sample java code for Caesar Cipher

key : each letter shift of two in alphabet order
caesar cipher encryption

eg: hello -----------jgnnq
encryption

import java.util.*;

public class encryption{

public static void main(String args[]){

Scanner myScanner=new Scanner(System.in);

String alpha="abcdefghijklmnopqrstuvwxyz";

String word,text="";

System.out.println("Enter the plain text");

word=myScanner.nextLine().toLowerCase();

System.out.println("cipher text");

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

boolean found=false;

char a=word.charAt(i);

int j=0;

while(j<alpha.length() && !found ){

char b=alpha.charAt(j);

if(a==' '){

text=text+" ";

found=true;

}

else if(a==b ){

found=true;

if(j<24){

text=text+alpha.substring(j+2,j+3);

}

else{

text=text+alpha.substring(j-alpha.length()+2,j-alpha.length()+3);

}

}

j++;

}

}

System.out.print(text);

}

}

output of the above code

   

caesar cipher decryption

key : each letter shift of two in alphabet order

eg: jgnnq-----------hello

decryption

import java.util.*;
public class decryption{
public static void main(String args[]){
Scanner myScanner=new Scanner(System.in);
String alpha="abcdefghijklmnopqrstuvwxyz";
String word,text="";
System.out.println("Enter the cipher text");
word=myScanner.nextLine().toLowerCase();
  System.out.println("Original text");
for(int i=0;i<word.length();i++){
boolean found=false;
char a=word.charAt(i);
int j=0;
while(j<alpha.length() && !found ){
char b=alpha.charAt(j);
if(a==' '){
text=text+" ";
found=true;
}
else if(a==b ){
found=true;
if(j>1){
text=text+alpha.substring(j-2,j-1);
}
else{
text=text+alpha.substring(alpha.length()-2+j,alpha.length()-1+j);
}
}
j++;
}
}
System.out.print(text);
}
}         

output of the above code