Cracks a three character password which is encrytped usinf DES useed in linux systems. Uses a generate program which creates all the combinations possible for the three characer password.

crack.c

#define _XOPEN_SOURCE 
#include <stdio.h>
#include <cs50.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>

//char name[7312000][5];

int generate(char hash[])
{
    //sFILE *f;
    
    char name[5];
    int i,j,k,l;
    int num[52]={65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,
    84,85,86,87,88,89,90,97,98,99,100,101,102,103,104,105,106,107,108,
    109,110,111,112,113,114,115,116,117,118,119,120,121,122};
    
    
    
    
    
    name[1]='\0';
    
    for(i=0;i<52;i++)
    {
        name[0]=num[i];
       // printf("%s\n",crypt(name,"50"));
        if(strcmp(hash,crypt(name,"50"))==0)
        {
            printf("%s\n",name);
            return 0;
        }
    }
  
    
    name[2]='\0';
    
     for(i=0;i<52;i++)
    {
        name[0]=num[i];
        for(j=0;j<52;j++)
        {
            name[1]=num[j];
            if(strcmp(hash,crypt(name,"50"))==0)
        {
            printf("%s\n",name);
            return 0;
        }
        }
    }
    
    name[3]='\0';
    
     for(i=0;i<52;i++)
    {
        name[0]=num[i];
        for(j=0;j<52;j++)
        {
            name[1]=num[j];
            for(k=0;k<52;k++)
            {
                name[2]=num[k];
                 if(strcmp(hash,crypt(name,"50"))==0)
        {
            printf("%s\n",name);
            return 0;
        }
            }
           
        }
    }
    
    name[4]='\0';
    
     for(i=0;i<52;i++)
    {
        name[0]=num[i];
        for(j=0;j<52;j++)
        {
            name[1]=num[j];
            for(k=0;k<52;k++)
            {
                name[2]=num[k];
                for(l=0;l<52;l++)
                {
                    name[3]=num[l];
                    if(strcmp(hash,crypt(name,"50"))==0)
        {
            printf("%s\n",name);
            return 0;
        }
                  
                }
            }
           
        }
    }
    
    
    
    
   // fclose(f);
    
    return 0;
    
    
    
}

int main(int argc, char* argv[])
{
    //Ensure proper usage
    if(argc!=2)
    {
        printf("Usage: crack HashPassword\n");
        return 1;
    }
  //  printf("%s",argv[1]);
    generate(argv[1]);
    
    
}

generate.c

#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *f;
    
    char name[5];
    int i,j,k;//,l;
    int num[52]={65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,
    84,85,86,87,88,89,90,97,98,99,100,101,102,103,104,105,106,107,108,
    109,110,111,112,113,114,115,116,117,118,119,120,121,122};
    
    
    
    if ((f = fopen("feed.txt", "w")) == NULL)
    {
        printf("Error");
        return 1;
    }
    
    name[1]='\0';
    
    for(i=0;i<52;i++)
    {
        name[0]=num[i];
        
        fprintf(f,"%s\n",name);
    }
  
    
    name[2]='\0';
    
     for(i=0;i<52;i++)
    {
        name[0]=num[i];
        for(j=0;j<52;j++)
        {
            name[1]=num[j];
             fprintf(f,"%s\n",name);
        }
    }
    
    name[3]='\0';
    
     for(i=0;i<52;i++)
    {
        name[0]=num[i];
        for(j=0;j<52;j++)
        {
            name[1]=num[j];
            for(k=0;k<52;k++)
            {
                name[2]=num[k];
                  fprintf(f,"%s\n",name);
            }
           
        }
    }
    
   /* name[4]='\0';
    
     for(i=0;i<52;i++)
    {
        name[0]=num[i];
        for(j=0;j<52;j++)
        {
            name[1]=num[j];
            for(k=0;k<52;k++)
            {
                name[2]=num[k];
                for(l=0;l<52;l++)
                {
                    name[3]=num[l];
                  fprintf(f,"%s\n",name);
                  
                }
            }
           
        }
    }
    */
    
    
    
    fclose(f);
    
    return 0;
    
    
    
    
    
    
}