RE: Elemental Subset Sum Problem

Consider.

gcd(N, p) = 1 ⇒ N^Φ(p) mod p = 1 by Euler's theorem

gcd(N, p) ≠ 1, N = p^b ∙ a, p^b ≡ 0 mod p ⇒ N^Φ(p) mod p = 0

Hope this helps