/*Sinple Ex-Or encryption/decryption*/
#include<stdio.h>

void encr(char *src,char *dest,char *keyword);

int main()
{
	int len;
	char data,encrypted_text,decrypted_text,key;
	
	puts("Enter the length of the string: ");
	scanf("%d",&len);
	
	data=(char *)malloc(sizeof(len+1));
	encrypted_text=(char *)malloc(len+1);
	decrypted_text=(char *)malloc(len+1);
	key=(char *)malloc(len+1);

	getchar();/*get character echoed*/
	
	puts("Enter the data: ");
	fgets(data,len,stdin);

	puts("Enter the key (any string of characters): ");
	fgets(key,strlen(data),stdin);

	puts("Press Return to view results.");
	
	puts("Data: ");
	puts(data);
	
	encr(data,encrypted_text,key);
	
	puts("Encrypted text: ");
	puts(encrypted_text);
	
	encr(encrypted_text,decrypted_text,key);
	
	puts("Decrypted text: ");
	puts(decrypted_text);
	
	puts("Press Return to exit.");
	getchar();
}

void encr(char *src,char *dest,char *keyword)
{
	char *p,*q,*r;

	for(p=src,q=dest,r=keyword;*p!='\0';p++,q++,r++)
	{
		if(*r=='\0')
			r=keyword;
		*q=*p^*r;
	}
	*q='\0';
	return;
}