17 replies to this topic

[Danerd100]

Okay, Say I was making a program that required a product key. Is this a good set of formulas?

I have a textbox that can store 9 digits and then it has 7 check digits

Private Sub CommandButton1_OnEvent()

  Dim a as string = TextBox1.Text

  Dim a1 as integer = val(Mid(a, 1, 1))

  Dim a2 as integer = val(Mid(a, 2, 1))

  Dim a3 as integer = val(Mid(a, 3, 1))

  Dim a4 as integer = val(Mid(a, 4, 1))

  Dim a5 as integer = val(Mid(a, 5, 1))

  Dim a6 as integer = val(Mid(a, 6, 1))

  Dim a7 as integer = val(Mid(a, 7, 1))

  Dim a8 as integer = val(Mid(a, 8, 1))

  Dim a9 as integer = val(Mid(a, 9, 1))

  dim key1 as integer = (a1^2 + a5) mod 10

  dim key2 as integer = (a2 / a8) mod 10

  dim key3 as integer = (a3 * a4 / a6) mod 10

  dim key4 as integer = (a7 + a9 / a1) mod 10

  dim key5 as integer = (a3 - a8 * a7 ^0.5 + a1 -a4) mod 10

  dim key6 as integer = (a2 + a5^2 * a6 - a7 * a9) mod 10

  dim key7 as integer = (((a1 + a3 * a2 / a4 * a5) mod a7 * (a8 + a9)) mod 10)

  Label1.text = a & key1 & key2 & key3 & key4 & key5 & key6 & key7

End Sub

If I enter the number 975224897
I get 975224897-(These are the same as the top)-3028234
without the dashes

I would then write a decryptor into the main program that checks the 7 check digits

[WingedPanther]

I think most keys are hex values that have a common hash value (usually a pretty simple hash). What you're proposing could work well, however.

[Xav]

Bear in mind that an automated tool could be implemented to run through all the most common ways, so maybe pick a standard algorithm and then just make a slight change, to confuse the hackers. :)

[Danerd100]

Trust me, the software that I am using this for, people won't hack. It is for schools to use. I just wanted to make it for a new feature, as i have not yet thought of another project to work on.

[Xav]

OK. I suppose the children won't really feel the need to crack open the system, I suppose. :)

[Danerd100]

It isn't for the kids...A brief explanation of my program...

Okay, Quiz Bowl is a game like jeopardy. There are toss Up questions, and bonus questions and 2 teams. I have made a score board for quiz bowl that is available for mac and windows. I am going to sell this. I will have keys registered (this is what I hope to do, though it may be a long way off) so only 1 computer can run each key. I will give each school about 25 keys they can use (because that is about how many they need)

[Xav]

OK - but just make sure people can't take a look at the sample keys, and work out their own...

[Danerd100]

I know, only the tech guys who will be installing it will be able to look at it.

[Xav]

Well, only the tech guys who will be installing it will have access to the program anyway, so... well, I suppose you just have to trust them on this one.

[Danerd100]

I mainly added the feature for fun. You can trust most schools.

BTW

Others will be running the scoreboards during the tournaments. The tech guys most likely won't be there, I will be there for the first few at each school as support and troubleshooting.

...Man, that's kinda wierd, I will be the support guy...on a program i wrote...and people will use...maybe...

lol

[Xav]

I hope so. I've never actually written anything that can be sold - just for fun. :)

[MeTh0Dz]

You'll have to hope that no one has much computer knowledge, because it would be very simple to reverse engineer and crack this algorithm.

Just my 2 cents.