A man owned a casino and invited some friends.
It was a dark stormy night, and they all placed their money on the table right before the lights went out.
When the lights came back on, the money was gone.
The owner put a rooster in an old rusty tea kettle.
He told everyone to get in line and touch the kettle after he turned the lights off, and the rooster will crow when the robber touched it.
After everyone touched it, the rooster didn't crow, so the man told everyone to hold out their hands.
After examining all the hands, he pointed out who the robber was.
How did he know who stole the money?
Because the tea kettle was rusty, whoever touched it would have rust on their hands. The robber didn't touch the kettle, therefore he was the only one whose hands weren't rusty.
Suppose you want to send in the mail a valuable object to a friend. You have a box which is big enough to hold the object. The box has a locking ring which is large enough to have a lock attached and you have several locks with keys. However, your friend does not have the key to any lock that you have. You cannot send the key in an unlocked box since it may be stolen or copied. How do you send the valuable object, locked, to your friend - so it may be opened by your friend?
Send the box with valuable object and a lock attached and locked. Your friend attaches his or her own lock and sends the box back to you. You remove your lock and send it back to your friend. Your friend may then remove the lock she or he put on and open the box.
Search: Man-in-the-middle attack
Peter celebrated his birthday on one day, and two days later his older twin brother, Paul, celebrated his birthday. How could this be?
When the mother of the twins went into labor, she was travelling by boat. The older twin, Paul, was born first, barely on March 1st. The boat then crossed a time zone, and the younger twin was born on February the 28th. In a leap year the younger twin celebrates his birthday two days before his older brother.
You walk up to a mountain that has two paths. One leads to the other side of the mountain, and the other will get you lost forever. Two twins know the path that leads to the other side. You can ask them only one question. Except! One lies and one tells the truth, and you don't know which is which. So, What do you ask?
You ask each twin "What would your brother say?"
This works because.... Well let's say the correct path is on the left side. So say you asked the liar "What would your brother say?" Well, the liar would know his brother was honest and he would say the left side, but since the liar lies, he would say right. If you asked the honest twin the same question, he would say right, because he knows his brother will lie. Therefore, you would know that the correct path was the left.
