January 8, 2002
Practical Aspects of Modern
Cryptography
How to Remotely Flip a Coin
•Bob
•After
receiving N from Alice, guess the
value of
b and send this guess to Alice.Bob wins if and only
if he correctly guesses
the value of b.
•Alice
•Randomly
select a bit bÎ{±1} and two large
integers
P and Q
– both
of type b.
•Compute
N = PQ.
•Send N to Bob.
After receiving b
from Bob, reveal P and
Q.
