@hacky02:~$ cat /Uebungen/Aufgabenblatt01/Aufgabe02/auth.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

char *salt = "$6$aGzikL66hsj/hs$";

int auth(char *username, char *password)
{
        int result = 0;
        char pw_user[20];
        char * pw_hash;

        // Prepare pw
        strcpy(pw_user, password);
        strcat(pw_user, username);

        // Get Hash
        printf("\n\nUser: %s\n", username);
        printf("Password: %s\n", password);
        pw_hash = crypt(pw_user, salt);
        printf("Password Hash: %s\n", pw_hash);


        if(strcmp(username, "00") == 0 &&
               strcmp(pw_hash, "$6$aGzikL66hsj/hs$1KUTqGk7PDos.KzfFdMEjakeURJ5GzB.HtgVnKXDAEQZju2td0RSp0l0hLtMKWMpUpyF.V/JwZg79Nv5mZmQx/") == 0)
        {
               result = 1;
        }

        return result;
}

void printUsage()
{
        printf("Usage: auth <username> <password>\n");
        exit(-1);
}

int main(int argc, char *argv[])
{
        if(argc < 3)
               printUsage();

        if(auth(argv[1], argv[2]) == 1)
        {
               printf("\n\n#####################################################\n");
               printf("#                                                   #\n");
               printf("#                !ACCESS GRANTED!                   #\n");
               printf("#                                                   #\n");
               printf("#####################################################\n\n\n");
               printf("Welcome %s!\n", argv[1]);

        }
        else
        {
               printf("\n\n#####################################################\n");
               printf("#                                                   #\n");
               printf("#                 !ACCESS DENIED!                   #\n");
               printf("#                                                   #\n");
               printf("#####################################################\n\n\n");
        }


        return 0;
}