Efficiently distinguishing prime and composite numbers is one of the fundamental
problems in number theory. A Fermat pseudoprime is a composite number
which satisfies Fermat’s little theorem for a specific base
:
. A Carmichael
number
is a Fermat
pseudoprime for all
with
.
D. Gordon (1987) introduced analogues of Fermat pseudoprimes and Carmichael
numbers for elliptic curves with complex multiplication (CM): elliptic pseudoprimes,
strong elliptic pseudoprimes and elliptic Carmichael numbers. It has previously been
shown that no CM curve has a strong elliptic Carmichael number. We give bounds
on the fraction of points on a curve for which a fixed composite number
can
be a strong elliptic pseudoprime. J. Silverman (2012) extended Gordon’s notion of
elliptic pseudoprimes and elliptic Carmichael numbers to arbitrary elliptic
curves. We provide probabilistic bounds for whether a fixed composite number
is an
elliptic Carmichael number for a randomly chosen elliptic curve.