5. Authentication:

In the simple old days, to recognize someone you'd just look at his face and try to remember who it is (if you didn't forget it in one of the Blue Screen of Death episodes). But there's a much better way, which is more mathematically-sound: RSA! Why try to remember a (many times ugly) face, when instead you can remember a person's 1024 bit RSA key? (remembering 1024 ones and zeros is a lot of fun! try it!) Then, when you meet the other person, and you want to be sure it is *really* that guy, not some Hannibal Lektor who pealed his face off and wore it, all you need to do is to make up a random number (try not to choose 7, because that is too easily guessable!), do some fun arithmetic with 1024 digit numbers, and then tell the other person the result (hoping that the other guy doesn't get bored by you reading out aloud the digits "one" and "zero" a thousand times) and ask him to try to guess the random number from it. If he succeeds, he's not Hannibal Lektor - but he's probably mad anyway.

Author |
Nadav Harâ€™El |

Work |
Hackers-IL Message No. 1,408 |