January 8, 2002
Practical Aspects of Modern Cryptography
Can Alice Cheat?
•Randomly pick large integers p, q, r, and s.
•Send Bob N = (4p+1)(4q+1)(4r–1)(4s–1).
•If Bob guesses –1, send                                 P = (4p+1)(4q+1) and Q = (4r–1)(4s–1).
•If Bob guesses +1, send                               P = (4p+1)(4r–1) and Q = (4q+1)(4s–1).