Pretty Darn Fun (PDF): The No-Padlock Padlock Trick


I’ve always liked tricks where you guess the combination of a padlock. But I wanted a more virtual version.

So I taught myself coding, infiltrated Adobe’s HQ posing as an intern called Garamond Futura, and through months of subtle persuasion, got them to include a guess-the-code feature into pdfs.

Okay, enough entirely believable backstory, what am I talking about?


The Inspiration

When getting some financial information for my tax return (yep, it’s a rock ‘n’ roll life), I received a password-protected pdf.

The Idea

When performing a virtual show for a special occasion (e.g. a birthday), send them an e-card as a password-protected pdf, telling them that the password is a 4-digit PIN. Have them try a few random numbers without success. Then explain that by working together, everyone can create the correct code to open it.

Ask multiple people to suggest numbers and then add them together to arrive at a ‘random’ PIN number.

They enter this into the pdf, and voila, they’re in. And then they discover your birthday e-card.

You should get a nice one-two reaction, of “Ooh, how amazing” as the password works, then “Aw, how sweet” as they see your thoughtful card.

And if they can share their screen while doing it, everyone can watch it happen.

The Method

As you’ve probably guessed, you just need to create a password-protected PDF, either using Adobe software or one of the free online alternatives. And then ‘influence’ the total number using any of the usual methods involving a pad or a calculator.


I first came across the idea of emailing an audience member a pdf for a trick, and them generating a number, in a post by John Haynes, who does so in the context of a different (and excellent) trick.

As ever, if you give it a go (or if I’ve reinvented the wheel), let me know.