/* 
 Atanas Dimitrov
 USER6
 Homework Assignment #3
 CS6900
 Dr. Li
 */

#include <strings.h>
#include <stdio.h>
#include "./crypt.h"

char password[8];
char letters[]={
	'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'
};

void decrypt(int var, int length)
{
	int i;
	char *enc_passwd;
        
	if(var==length)
	{
		//if this is a complete permutation then compare its encrypted version
		//with shadow file entry. and display as "password -> encrypted password" pair
		printf("%s\n", password);
		if (strcmp(enc_passwd=crypt(password, "vi"), "vi2mW5sahNOyE") == 0)
		{
                	printf("%s -> ",password);
			printf ("%s\n", enc_passwd);
			exit(0);
		}
        }
	else
	{
		//creates the next permutation by adding letters recursively
                for (i=0; i<sizeof(letters); i++)
		{
                        password[var] = letters[i];
                        decrypt(var+1, length);
                }
        }
}

int main()
{
	int i;
	//variable password length from 1 to 8 bytes (letters)
	for (i=1; i<9; i++)
	        decrypt(0, i);

	exit(0);
}

/*
Small range .. I have been running it for 2 days with no result. 
Unfortunately Monday I had to be @ school and there was a power outtage 
in my house tonight I only had time to run it for about 2-3 hours.
Basically in this algorithm as the others the password builds up 
recursively as if counting sequenced numbers (in this case base 28 - 1 
for each letter of the alphabet). The current file size is about 19 MB so 
I decided not to enclose it rather this information should be sufficient:

Atanas-Computer:~/school/cs6900/hw3 adimitro$ head output 
a
b
c
d
e
f
g
h
i
j
Atanas-Computer:~/school/cs6900/hw3 adimitro$ tail output 
gfbjt
gfbju
gfbjv
gfbjw
gfbjx
gfbjy
gfbjz
gfbka
gfbkb
gfbk (interrupted disk write..)
Atanas-Computer:~/school/cs6900/hw3 adimitro$ 

 */