Schneier on Security

Clive Robinson • October 20, 2021 7:41 PM

@ David Leppik, ALL,

I’m guessing that if you put fingers on the whole row of numbers before pressing, you can defeat this particular AI.

What you need is a little sleight of hand. Or press the button with the thumb under hand.

Step 1) Hold your “dominant” hand out in front of you flat with the back of the hand upper most.

Step 2) Bring your thumb under your hand so the thumb-nail is at the base of the little finger. Seen from the top your whole thumb down to the wrist should be “under your hand” and out of sight. If not practice moving the thumb from sticking out straight sideways to touching under the little finger untill your thumb is “limber enough”.

Step 3) Now gently bend the fingers a little like you were starting to make a young childs fist with the thumb in (as adults we should know never to make a fist with the thumb in as that is an easy way to break it even in play sparing).

Step 4) Now put your hand down on the table so all your finger tips touch the table, but your thumb does not.

Step 5) Now use your thumb tip to touch each of the fingers where they touch the table. Do this in turn in each direction several times and randomly as well.

Do this as a practice excercise a few times. With practice you can get all of the thumb down to the wrist to be under the hand and out of sight from above yet be able to still touch individual finger tips on the table.

If you now hold your other hand flat and across your dominant hand at around 90 degrees you will cover the small movment at the side of your dominant hand as you move your thumb.

With practice you will be able to press any one of the buttons under your hand without it being visable.

Now you have to practice moving both hands so you dial say the first and last of your PIN number with your thumb and the other digits with your fingers but with your other hand over them.

With practice you can make it look like you are pressing a button with a finger, when in fact you are pressing an entirely different button with your thumb. Moving the other hand across the top makes it difficult to see what is actually going on even when recorded to a video clip.

Oh and if you master it you will find that you can put your hand over a coin on the table and flip it over with your thumb. It’s a little trick that comes in handy when some one calls heads or tails.

But you are now asking “how do you know which way it’s up?…

That’s easy when you flip a coin from your thumb it goes up and you catch it in your hand and bring it down onto the back of your other hand.

Now if you practice the catch you will discover you can see which way up it is as you bring it down on the back of your other hand…

It used to amaze my son and others when he was quite young. As a party trick / magic for a kids party it’s a fun little thing to do, but don’t do it with adults as they catch on quick and they might not find it either fun or funny… Especially if you go on to learn how to do it the other way up with say the ring finger so you can deal cards off the bottom of the pack etc.

Any way don’t worry I won’t get “Thrown out of the Magic Circle” for having told you… Because I never joined in the first place as most of the tricks are to obvious 😉