#include
int main(void)
{
char str[100],str1[100],target[100],target1[100],find[]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
int len,key,i,j;
clrscr();
printf("enter plaintext : ");
scanf("%[^\n]",str);
len=strlen(str);
//printf("length=%d",len);
printf("enter key:");
scanf("%d",&key);
for(i=0;i
for(j=0;j<26;j++)
{
if(str[i]==find[j])
{
if(j+key>=26)
{
target[i]=find[j]-26+key;
}
else
{
target[i]=find[j+key];
}
}
}
}
target[i]='\0';
printf("encrypted:%s",target);
printf("\nenter cipher text for descryption: ");
getchar();
scanf("%[^\n]",str1);
printf("enter key:");
scanf("%d",&key);
for(i=0;i
for(j=0;j<26;j++)
{
if(str1[i]==find[j])
{
if(j-key<0)
{
target1[i]=find[j]+26-key;
}
else
{
target1[i]=find[j-key];
}
}
}
}
target1[i]='\0';
printf("plaintext is :%s",target1);
getch();
return 0;
}
