# Revision history [back]

### Quick check that an elliptic curve has composite order

Assume E is an Elliptic Curve over the field Fp, with p a known prime, for example as obtained by

p = next_prime(p)
F = GF(p)
E = EllipticCurve([F(3),F(2)])


Is there a much faster way to check that E is of composite order (the most common case) than using the obvious

not E.cardinality().is_prime()


That could speed up the search of prime-order curves.

 2 retagged FrédéricC 5125 ●3 ●43 ●111

### Quick check that an elliptic curve has composite order

Assume E is an Elliptic Curve over the field Fp, with p a known prime, for example as obtained by

p = next_prime(p)
F = GF(p)
E = EllipticCurve([F(3),F(2)])


Is there a much faster way to check that E is of composite order (the most common case) than using the obvious

not E.cardinality().is_prime()


That could speed up the search of prime-order curves.

 3 retagged FrédéricC 5125 ●3 ●43 ●111

### Quick check that an elliptic curve has composite order

Assume E is an Elliptic Curve over the field Fp, with p a known prime, for example as obtained by

p = next_prime(p)
F = GF(p)
E = EllipticCurve([F(3),F(2)])


Is there a much faster way to check that E is of composite order (the most common case) than using the obvious

not E.cardinality().is_prime()


That could speed up the search of prime-order curves.