Caesar Cipher

AIM:

To implement a program for encrypting a plain text and decrypting a cipher text using

Caesar Cipher (shift cipher) substitution technique.

CODE:

#include<stdio.h>

//ASCII RANGE CAN BE MODIFIED HERE

int ascii_min=32;

int ascii_max=126;

void encryption(char p[], int key, int length){

int range,i;

for(i=0;i<length;i++){

p[i]=p[i]-ascii_min;

}

for(i=0;i<length;i++){

p[i]=(p[i]+key)%range;

}

for(i=0;i<length;i++){

p[i]=p[i]+ascii_min;

}

printf("\nYour Cipher Text is: %s\n",p);

}

void decryption(char c[], int key, int length){

int i;

for(i=0;i<length;i++){

c[i]=c[i]-ascii_min;

}

for(i=0;i<length;i++){

c[i]=(c[i]-key)%range;

}

for(i=0;i<length;i++){

c[i]=c[i]+ascii_min;

}

printf("\nYour Plain Text is: %s\n",c);

}

void main(){

int key;

char data[30];

printf("ENCRYPTION FUNCTION\n---------------------------");

printf("\nEnter the Plain text: ");

gets(data);

printf("\nEnter the Key value: ");

scanf("%d",&key);

encryption(data,key,strlen(data));

gets(data);

printf("\n\n\nDECRYPTION FUNCTION\n---------------------------");

printf("\nEnter the Cipher text: ");

gets(data);

printf("\nEnter the Key value: ");

scanf("%d",&key);

decryption(data,key,strlen(data));

}

OUTPUT:-