9. Implement data encryption and data decryption
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void main()
{
 int i,ch,lp;
 char cipher[50],plain[50];
 char key[50];
 while(1)
 {
 printf("\n.....MENU....\n");
 printf("\n 1.Data Encryption\t \n \n 2.Data Decryption\t \n \n3.exit");
 printf("\n Enter your choice:");
 scanf("%d",&ch);
 switch(ch)
 {
 case 1:printf("\n Data Encryption");
 printf("\n Enter the plain text");
 fflush(stdin);
 scanf("%s",plain);
 printf("Enter the encryption key:");
 scanf("%s",key);
 lp=strlen(key);
 for(i=0;plain[i]!='\0';i++)
cipher[i]=plain[i]^lp;
 cipher[i]='\0';
 printf("\n The encrypted text is :");
 puts(cipher);
 break;
 case 2:
 printf("\n Data Decryption");
 for(i=0;cipher[i]!='\0';i++)
 plain[i]=cipher[i]^lp;
 printf("\n Decryption text is:");
 puts(plain);
 break;
 case 3:exit(0);
 }
 }
}