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PnP: using PDF password to release exclusive content

6 replies [Last post]
larienna's picture
Joined: 07/28/2008

I had an idea lately and I want to know it is actually a good idea.

Let say I publish a game as PDF and after the release I want to give to new material, like rule and components update, that should be only exclusively download by people that actually bought the game.

My solution was to pasword protect the PDF and give the key to get the password in the rule book which was sold. Since I don't want a unique identifier for each copy sold, so what I wanted to do is:

- The rule book comes with a decoding table. Each game would have a different table but it would work the same way.

- Each PDF file released will have a numeric code. If you pass this code in the table you get the password required to open the PDF.

What do you think?
Does it really worth it?
Is it going to get cracked fast, or are the key table going to be distributed on the net rapidly?


Here is how it works. The key table is a 5x5 grid where each square contains a letter from A to Y. The rows are numbered 0-4, the columns 5-9.

When you download the PDF file, you get a numeric code like 1526-3748. For each pair of number you look at the matching row/columns, the result in the grid is a letter of the password. So for example 15 means row 1, column 5.

What prevent people, who does not have the key, to decode any value, even if they know how it works, is that the letters in the grid are always distributed differently.

I also get many grid construction possibilities so I will never run out of key table combinations and each game can have a unique key table.

What do you think?

rpghost's picture
Joined: 03/03/2009
Password protection is easy

Password protection is easy to rip out of a pdf. You should make use of a site like to sell your product and they can distribute updates for you. In the end you need to trust your customer, not make it hard on them.


larienna's picture
Joined: 07/28/2008
So you mean that websites

So you mean that websites that sell print and play games can also distribute free updates and add-ons to the people who ordered the original product?

Joined: 07/08/2009
If the new content is free . . .

. . . then why bother? Wouldn't someone who shared the original content, or received a shared version of the original content be just as likely to do it with this one?

I'm assuming the original content is needed for the new content.

I'm also assuming you don't have access to a system that is providing this service (since you'd, uh, probably know it!)


Joined: 08/28/2008
Password protection is

Password protection is definitely easy to overcome. You can download a free tool online to help you decrypt most protected files of which you "forgot" the password.

Next to that I guess I sort of miss the point in why you would want to to it like this and don't just provide errate/updates for free on your own website. Just like WOTC does with e.g. Dungeons and Dragons. Or is it that you want to give people a completely revised game? Maybe you can have people register their copy after buying it to receive free updates from you when they become available.

larienna's picture
Joined: 07/28/2008
OK, let me give you an

OK, let me give you an example.

I publish the game as PNP. Then I realises that there is a bug on the text of one of my cards. I submit an errata on my web site but I want to allow players re-print their cards with the new changes.

If I submit the cards for free, it gives players who did not buy the game access to those cards. Considering that there could be multiple erratas, that would almost give the game away.

Still, if the website that sell the game allow players who bought the game to download updates, this is OK because even if the update is free, only the people who paid for it will have access to the file.

For my password solution above, Everybody would have access to the files but only people who have the rule book would be able to decode the password. But as everybody said, decryption is pretty easy so the idea should be forgotten.

Joined: 04/14/2009
I think there's a game here somewhere!

You know?

Although I agree with everyone that said it's easy to crack a .pdf password, I was intrigued with your password mechanic. I think there might be an interesting game here somewhere. Perhaps a treasure hunting game, or a dungeon crawl that requires passwords to open doors or chests? It's just an inkling of an idea...but since I liked your password mechanic, (simple) I thought maybe your idea doesn't have to be abandoned...just re-routed for a different purpose! :)


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