Loop Training: Password Finder

[jasonsweeney]

I am teaching myself VBA. To learn how to write lopps I have challenged myself to do the following:

A macro that cracks a password. I have a macro below, but please let me know if any of you can come up with a quicker way to search the various strings (beyond the obvious of "Application.ScreenUpdating = False").

So here is the challenge:

In the workbook:
Cell A1 contains the 7-digit password, say "eureka" (this is the password I want the macro to find)
Cell A2 is blank (this is the cell I want the macro to test strings)


Note:
- This macro will look only for a 7-digit password, which password shall be in lower-case letters only (the lowercase alphabet = Chr(97) through Chr (122))
- This macro will also display the time the search begins and stops.

Here is my first try at a macro to hack the password:
_______________
Sub passwordsearch()
'
' 7 DIGIT SEARCH
'
Dim a As Integer, b As Integer, c As Integer
Dim d As Integer, e As Integer, f As Integer, g As Integer
Dim Crack As String
Range("a5").Value = "Start: " & Now()
On Error Resume Next
If Range("A2").Value <> Range("A1").Value Then
Do
For a = 97 To 122: For b = 97 To 122: For c = 97 To 122
For d = 97 To 122: For e = 97 To 122: For f = 97 To 122: For g = 97 To 122
Crack = Chr(a) & Chr(b) & Chr(c) & Chr(d) & Chr(e) & Chr(f) & Chr(g)
Range("A2").Value = Crack
If Range("A2").Value = Range("A1").Value Then
With Range("a6")
.Value = "Stop: " & Now()
End With
Exit Sub
End If
Next: Next: Next: Next: Next: Next: Next
Loop
End If
End Sub
___________________

I launch this macro from a button on the worksheet. Any reccomendations are appreciated!

-- Jason

[Roy Wagner]

Jason,

'In your unique example, you know where the password is.
'With that in mind, I would do a parsing loop. The example
'below determines the password by trial and error regardless
'of its length. There are only 3 changes on the sheet, so it
'isn't necessary to disable screen updating. My test took less
'than 1 second to find the answer.

'Nesting loops 7 deep is definitely going to slow things down.
'The cycles on your g loop would be phenominal in your case.
'Put an extra variable (make it a double) in the g loop to see
'what I mean. Do a control break (on your code) after a few minutes,
'hit debug and see what you gLoop counter says. Yikes!

Dim Pword As Range
Dim Solution As String
Dim LenPword As Integer, x As Integer
Range("a5").Value = "Start: " & Now()
Set Pword = Range("A1")
LenPword = Len(Pword)
For x = 1 To LenPword
For y = 97 To 122
If Mid(Pword, x, 1) = Chr(y) Then
Solution = Solution + Chr(y)
If x = LenPword Then
Range("A2").Value = Solution
Range("A6").Value = "Stop: " & Now()
Exit Sub
End If
End If
Next
Next


'Roy
--
(delete .nospam)




"jasonsweeney" wrote:

>
> I am teaching myself VBA. To learn how to write lopps I have challenged
> myself to do the following:
>
> A macro that cracks a password. I have a macro below, but please let
> me know if any of you can come up with a quicker way to search the
> various strings (beyond the obvious of "Application.ScreenUpdating =
> False").
>
> So here is the challenge:
>
> In the workbook:
> Cell A1 contains the 7-digit password, say "eureka" (this is the
> password I want the macro to find)
> Cell A2 is blank (this is the cell I want the macro to test strings)
>
>
> Note:
> - This macro will look only for a 7-digit password, which password
> shall be in lower-case letters only (the lowercase alphabet = Chr(97)
> through Chr (122))
> - This macro will also display the time the search begins and stops.
>
> Here is my first try at a macro to hack the password:
> _______________
> Sub passwordsearch()
> '
> ' 7 DIGIT SEARCH
> '
> Dim a As Integer, b As Integer, c As Integer
> Dim d As Integer, e As Integer, f As Integer, g As Integer
> Dim Crack As String
> Range("a5").Value = "Start: " & Now()
> On Error Resume Next
> If Range("A2").Value <> Range("A1").Value Then
> Do
> For a = 97 To 122: For b = 97 To 122: For c = 97 To 122
> For d = 97 To 122: For e = 97 To 122: For f = 97 To 122: For g
> = 97 To 122
> Crack = Chr(a) & Chr(b) & Chr(c) & Chr(d) & Chr(e) & Chr(f) &
> Chr(g)
> Range("A2").Value = Crack
> If Range("A2").Value = Range("A1").Value Then
> With Range("a6")
> .Value = "Stop: " & Now()
> End With
> Exit Sub
> End If
> Next: Next: Next: Next: Next: Next: Next
> Loop
> End If
> End Sub
> ___________________
>
> I launch this macro from a button on the worksheet. Any
> reccomendations are appreciated!
>
> -- Jason
>
>
> --
> jasonsweeney
> ------------------------------------------------------------------------
> jasonsweeney's Profile: http://www.excelforum.com/member.php...fo&userid=5222
> View this thread: http://www.excelforum.com/showthread...hreadid=393619
>
>

[Roy Wagner]

Dim LenPword As Integer, x As Integer
should be
Dim LenPword As Integer, x As Integer, y as Integer





"Roy Wagner" wrote:

> Jason,
>
> 'In your unique example, you know where the password is.
> 'With that in mind, I would do a parsing loop. The example
> 'below determines the password by trial and error regardless
> 'of its length. There are only 3 changes on the sheet, so it
> 'isn't necessary to disable screen updating. My test took less
> 'than 1 second to find the answer.
>
> 'Nesting loops 7 deep is definitely going to slow things down.
> 'The cycles on your g loop would be phenominal in your case.
> 'Put an extra variable (make it a double) in the g loop to see
> 'what I mean. Do a control break (on your code) after a few minutes,
> 'hit debug and see what you gLoop counter says. Yikes!
>
> Dim Pword As Range
> Dim Solution As String
> Dim LenPword As Integer, x As Integer
> Range("a5").Value = "Start: " & Now()
> Set Pword = Range("A1")
> LenPword = Len(Pword)
> For x = 1 To LenPword
> For y = 97 To 122
> If Mid(Pword, x, 1) = Chr(y) Then
> Solution = Solution + Chr(y)
> If x = LenPword Then
> Range("A2").Value = Solution
> Range("A6").Value = "Stop: " & Now()
> Exit Sub
> End If
> End If
> Next
> Next
>
>
> 'Roy
> --
> (delete .nospam)
>
>
>
>
> "jasonsweeney" wrote:
>
> >
> > I am teaching myself VBA. To learn how to write lopps I have challenged
> > myself to do the following:
> >
> > A macro that cracks a password. I have a macro below, but please let
> > me know if any of you can come up with a quicker way to search the
> > various strings (beyond the obvious of "Application.ScreenUpdating =
> > False").
> >
> > So here is the challenge:
> >
> > In the workbook:
> > Cell A1 contains the 7-digit password, say "eureka" (this is the
> > password I want the macro to find)
> > Cell A2 is blank (this is the cell I want the macro to test strings)
> >
> >
> > Note:
> > - This macro will look only for a 7-digit password, which password
> > shall be in lower-case letters only (the lowercase alphabet = Chr(97)
> > through Chr (122))
> > - This macro will also display the time the search begins and stops.
> >
> > Here is my first try at a macro to hack the password:
> > _______________
> > Sub passwordsearch()
> > '
> > ' 7 DIGIT SEARCH
> > '
> > Dim a As Integer, b As Integer, c As Integer
> > Dim d As Integer, e As Integer, f As Integer, g As Integer
> > Dim Crack As String
> > Range("a5").Value = "Start: " & Now()
> > On Error Resume Next
> > If Range("A2").Value <> Range("A1").Value Then
> > Do
> > For a = 97 To 122: For b = 97 To 122: For c = 97 To 122
> > For d = 97 To 122: For e = 97 To 122: For f = 97 To 122: For g
> > = 97 To 122
> > Crack = Chr(a) & Chr(b) & Chr(c) & Chr(d) & Chr(e) & Chr(f) &
> > Chr(g)
> > Range("A2").Value = Crack
> > If Range("A2").Value = Range("A1").Value Then
> > With Range("a6")
> > .Value = "Stop: " & Now()
> > End With
> > Exit Sub
> > End If
> > Next: Next: Next: Next: Next: Next: Next
> > Loop
> > End If
> > End Sub
> > ___________________
> >
> > I launch this macro from a button on the worksheet. Any
> > reccomendations are appreciated!
> >
> > -- Jason
> >
> >
> > --
> > jasonsweeney
> > ------------------------------------------------------------------------
> > jasonsweeney's Profile: http://www.excelforum.com/member.php...fo&userid=5222
> > View this thread: http://www.excelforum.com/showthread...hreadid=393619
> >
> >

[jasonsweeney]

Roy,

Good code. I like it. I had not though to use the len and mid functions. As I read your code, you take the first letter of the PASSWORD and compare it against a the letters "a" through "z" until a match is found. Then, the macro grabs the second letter of the password...etc. I like it.


However, I was assuming that the password was NOT known. I had to have a password for my macro to find, so I chose eureka. I was trying to emulate the non-unique situation where we have no idea what the password is, so we want the macro to brute-force its way to the solution...but as you note, my macro takes forever. I let it try to find "eureka" and I had to make it stop after 4 hours of trying.... There has got to be a more effecient way of checking all possible solutions...

[Greg Wilson]

A few suggestions based only on theory:
1) Declare the variables a to g as Long. As I'm told, the long variable type
is native to Excel while integers, even though they are a simpler data type,
are converted to longs anyways.
2) Streamline the contents inside the loop as much as possible. The code
inside the loop must be evaluated for each iteration which is many thousands
or even millions of times. In particular, don't do anything unnecessary to
the worksheet such as change a cell's value from within the loop. Note that,
in your code, all of the following must be evaluated (and, in the case of
A2's value executed) with each iteration:

> Range("A2").Value = Crack
> If Range("A2").Value = Range("A1").Value Then
> With Range("a6")
> .Value = "Stop: " & Now()
> End With
> Exit Sub

3) I replaced all of the above with the following. I suspect that comparing
one variable (memory location) to another directly rather than comparing cell
values is more efficient:

If p = pwd Then GoTo EndMsg

4) I didn't see the point of the Do...Loop so I removed it. Same for first
If...Then construct: "If Range("A2").Value <> Range("A1").Value Then"

All of the above said, if you do the math, it will probably take days (!!!)
to break 7 character passwords if you don't actually know the number of
characters - i.e. you have to test all possibilities from 1 to 7 characters.
And this assumes that only lower case alphabetic characters are used. Include
numbers and upper case and it will take till eternity. And then there's
punctuation.

Regards,
Greg

Sub passwordsearch()
Dim a As Long, b As Long, c As Long
Dim d As Long, e As Long, f As Long, g As Long
Dim pwd As String, p As String

pwd = Range("A1").Value
Range("a5").Value = "Start: " & Now()

Application.ScreenUpdating = False
For a = 97 To 122: For b = 97 To 122: For c = 97 To 122
For d = 97 To 122: For e = 97 To 122: For f = 97 To 122
For g = 97 To 122

p = Chr(a) & Chr(b) & Chr(c) & Chr(d) & Chr(e) & Chr(f) & Chr(g)
If p = pwd Then GoTo EndMsg

Next: Next: Next: Next: Next: Next: Next

EndMsg:
Range("a6").Value = "Stop: " & Now()
Application.ScreenUpdating = True
End Sub

"jasonsweeney" wrote:

>
> I am teaching myself VBA. To learn how to write lopps I have challenged
> myself to do the following:
>
> A macro that cracks a password. I have a macro below, but please let
> me know if any of you can come up with a quicker way to search the
> various strings (beyond the obvious of "Application.ScreenUpdating =
> False").
>
> So here is the challenge:
>
> In the workbook:
> Cell A1 contains the 7-digit password, say "eureka" (this is the
> password I want the macro to find)
> Cell A2 is blank (this is the cell I want the macro to test strings)
>
>
> Note:
> - This macro will look only for a 7-digit password, which password
> shall be in lower-case letters only (the lowercase alphabet = Chr(97)
> through Chr (122))
> - This macro will also display the time the search begins and stops.
>
> Here is my first try at a macro to hack the password:
> _______________
> Sub passwordsearch()
> '
> ' 7 DIGIT SEARCH
> '
> Dim a As Integer, b As Integer, c As Integer
> Dim d As Integer, e As Integer, f As Integer, g As Integer
> Dim Crack As String
> Range("a5").Value = "Start: " & Now()
> On Error Resume Next
> If Range("A2").Value <> Range("A1").Value Then
> Do
> For a = 97 To 122: For b = 97 To 122: For c = 97 To 122
> For d = 97 To 122: For e = 97 To 122: For f = 97 To 122: For g
> = 97 To 122
> Crack = Chr(a) & Chr(b) & Chr(c) & Chr(d) & Chr(e) & Chr(f) &
> Chr(g)
> Range("A2").Value = Crack
> If Range("A2").Value = Range("A1").Value Then
> With Range("a6")
> .Value = "Stop: " & Now()
> End With
> Exit Sub
> End If
> Next: Next: Next: Next: Next: Next: Next
> Loop
> End If
> End Sub
> ___________________
>
> I launch this macro from a button on the worksheet. Any
> reccomendations are appreciated!
>
> -- Jason
>
>
> --
> jasonsweeney
> ------------------------------------------------------------------------
> jasonsweeney's Profile: http://www.excelforum.com/member.php...fo&userid=5222
> View this thread: http://www.excelforum.com/showthread...hreadid=393619
>
>

[jasonsweeney]

Greg,

Thanks for the suggestions. That sped up the calculations significantly. It takes about 24 minutes to test all possible lower-case 7-digit passwords beggining with the letter "a". That would translate into approximately 10.5 hours for a search of all possible 7-digit lower-case passwords, with a single search pattern.

better...but still slow. Then again, I am asking the computer to try just a tad over 8 Billion possible passwords...

Thanks again...