Note on the generation of p 0 for RSA keysets
Michael J. Ganley · Electronics Letters · 1990
A note has been published by Clayden regarding the value p0 = sr−1 (mod rs) − rs−1 (mod rs) (where r and s are distinct primes). This value of p0 can be used in the generation of strong primes for the RSA public key cryptosystem. In another paper, Gordon requires whichever of p0 or p0 + rs is odd to generate the strong prime. Clayden's note gives a proof of the fact that it is always the value of p0 + rs that is odd. He also commented that, as this is not necessarily the case if either r or s is not prime, then the oddness of p0 + rs could be used as an extra test for the primality of both r and s.