brute force attack. need help with this assigment

[triplef00]

create a program that will do a brute force attack to crack passwords. program should ask user for a password and program should fin the password. experiment with different sizes, maximum of 4 characters. try passwords with numbers and letters of alphabet in both lower and upper case.

also calculate how long it takes to crack a password.
function difftime(then, now) in <ctime.h> library may be used

[MikeyBoy]

So what have you done so far?

Which aspect of the assignment, specifically, are you having trouble with?

[triplef00]

i have no idea at all.

[MikeyBoy]

We're not going to do your homework for you.

If this is genuinely an assignment you've been given, then you must have had some kind of teaching on how to write a simple C++ program, to the point where your teacher thinks you're able to handle this assignment.

Think about it. Imagine the steps you might have to go through to do crack a password. Then start trying to write the code to achieve those steps. When you hit a specific problem, then post your code here, explain the problem, and we'll help.

[Ericool]

you have several hints like

i need to use a function that calculate the time

maximum of 4 characters ( string size is 4 , right?)

try with numbers ( 0-9 and max is 9999 right? ( 4 digits remember...))

letters of alphabet( a,b,c,...z) right?

and capitals ( toupper(character) ?)

that should be enough I think

come up with something and we see if you are getting it, then.

[triplef00]

Thanks for that. But I knew that already. I just don't know how to put it in code. Anyways thanks for trying to help

[Ericool]

ask password
myPassword = userAnswer

time0 = libraryIhaveIncluded.getTime()

for ( character = 0 to 3 )
{
// brute force means try them all

for( number=0 to 9 )
{
if ( myPassword[ character ] == number)
//move to the next character
character ++
}

for ( letter = 'a' to 'z' )
{
if ( myPassword[ character ] == letter || myPassword[ character ] == toupper( letter )
character ++
}
}

time1 = libraryIhaveIncluded.getTime()

totalDuration = time1 - time0

print the password

print the time

smile

.

Something like that should help I guess...

[JLBorges]

> experiment with different sizes, maximum of 4 characters
> passwords with numbers and letters of alphabet in both lower and upper case.

Each character could be any one of 62 possibilities (26 lower case + 26 upper case + 10 digits)
If we have a password of four characters, the number of possibilities are 62 * 62 * 62 * 62 == 14776336
Brute force implies that these should be generated one by one till a match is found.

With a crude nested loop construct:

#include <iostream>
#include <string>

int main()
{
    const std::string pword = "Z2bw" ; 
    const std::string alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" ;

    unsigned long long n_attempt = 0 ;
    for( char first : alphabet ) for( char second : alphabet ) for( char third : alphabet )  for( char fourth : alphabet )
    {
        ++n_attempt ;
        if( pword == std::string{ first, second, third, fourth } )
        {
            std::cout << "found it at attempt# " << n_attempt << '\n' ;
            return 0 ;
        }
    }
}

http://coliru.stacked-crooked.com/a/da731830744e66a0

[triplef00]

thanks all. its really helpful