encrypt

I'm trying to encrypt this char array using pointer subscript notation and I need help with the algorithm. I don't understand how the ENCRYPTION_KEY affects the encryption and how to utilize it.

Code:

#include<iostream>
#include<conio.h>
#include<string>
#include<cstring>

using namespace std;


//encrypt(char *ptr);
const int ENCRYPTION_KEY = 1;
void main()
{

char temp1[26];
char temp2[26];
char password[11];
char *ptr;

cout<<"Please enter a password no more than 25 characters in length: ";
cin>>temp1;
cout<<temp1;
cout<<"Re-enter your password: "<<endl;
cin>>temp2;
cout<<temp2<<endl;
cout<<strcmp(temp1, temp2)<<endl;
     while (strcmp(temp1, temp2) !=0){
            cout<<"Invalid Password"<<endl;
            cout<<"Re-enter your password: "<<endl;
	        cin>>temp2;
			}

	 strncpy (password, temp1, 11);
	 password[10]='\0';
                 cout<<password<<endl;
                 ptr=password;

 //encrypt(ptr);
 getch();
 }

//void encrypt(char *ptr)
      //{
       //for (i =0; i<11; i++)
       //ptr[i] 
	//}

[code][/code]tagged by Salem

I don't know what you meant by the encryption key?
But I think that it should be the base you will do the encryption based on.