Cfrtjryk

I have implemented a program in C to crack passwords by generating all possible combinations of words ([A-Z][a-z]) up to the length of 5. While the program works, I would like to receive comments on the efficiency of the algorithm and other design decisions that would improve the code. The exercise is part of the course CS50 by Harvard.

I timed the program using unix's time and the time the program took to print all the combinations was
real 14m39.433s;
user 0m10.040s;
sys 0m36.356s.

CS50.h is a library developed for the course as training wheels for students. String (char*) and Bool are types defined in this library.

#define _XOPEN_SOURCE

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <cs50.h>



int main(int argc, char *argv)

{

    if(argc != 2)

    {

        printf("Usage: ./crack hashn");

        return 1;

    }



    string alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

    char password[6] = "";

    string hash = argv[1];

    char salt[3];

    memcpy(salt, hash, 2);

    salt[2] = '';



    bool flag = false;

    int alphabet_len = 52;



    for(int i = 0; i < alphabet_len; i++)

    {

        password[0] = alphabet[i];

        password[1] = password[2] = password[3] = password[4] = '';

        if(!strcmp(hash, crypt(password, salt)))

        {

            flag = true;

            break;

        }

        for(int j = 0; j < alphabet_len; j++)

        {

            password[1] = alphabet[j];

            password[2] = password[3] = password[4] = '';

            if(!strcmp(hash, crypt(password, salt)))

            {

                flag = true;

                break;

            }

            for(int k = 0; k < alphabet_len; k++)

            {

                password[2] = alphabet[k];

                password[3] = password[4] = '';

                if(!strcmp(hash, crypt(password, salt)))

                {

                    flag = true;

                    break;

                }

                for(int l = 0; l < alphabet_len; l++)

                {

                    password[3] = alphabet[l];

                    password[4] = '';

                    if(!strcmp(hash, crypt(password, salt)))

                    {

                        flag = true;

                        break;

                    }

                    for(int m = 0; m < alphabet_len; m++)

                    {

                        password[4] = alphabet[m];

                        if(!strcmp(hash, crypt(password, salt)))

                        {

                            flag = true;

                            break;

                        }

                    }

                    if(flag)

                        break;

                }

                if(flag)

                    break;

            }

            if(flag)

                break;

        }

        if(flag)

            break;

    }



    if(flag)

        printf("Password: %sn", password);

    else

        printf("Password not foundn");

}