January 8, 2002
Practical Aspects of Modern
Cryptography
Does This Work?
There is no known method (other than factoring) to
distinguish a “Type +1” product from a “Type –1” product.
•(4p+1)(4q+1) = 16pq+4p+4q+1 =
4(4pq+p+q)+1
•(4p–1)(4q–1) = 16pq–4p–4q+1 =
4(4pq–p–q)+1
Bob cannot
distinguish without factoring.