@@ -32,7 +32,7 @@ Indeed, the Renes-Costello-Batina complete addition formulas have a specialized
...
@@ -32,7 +32,7 @@ Indeed, the Renes-Costello-Batina complete addition formulas have a specialized
The second reason is that various cryptographic standards have adopted these kinds of curves~\cite{ETSI07,BSI12,FIPS186-4,Brainpool,SEC2}. Our results will apply to more commonly used curves if we mimic the standards.
The second reason is that various cryptographic standards have adopted these kinds of curves~\cite{ETSI07,BSI12,FIPS186-4,Brainpool,SEC2}. Our results will apply to more commonly used curves if we mimic the standards.
\subheading{Twist security.}
\subheading{Twist security.}
In the case an implementor uses formulas that do not depend on any of the constants $a$ and $b$, they could choose to omit checking whether the input point lies on the curve. To prevent invalidcurve attacks in this case, $E$'s twist ($E^d$) must also be of prime order. Then, the first valid value for $b$ is $13318$.
In the case an implementor uses formulas that do not depend on any of the constants $a$ and $b$, they could choose to omit checking whether the input point lies on the curve. To prevent invalid-curve attacks in this case, $E$'s twist ($E^d$) must also be of prime order. Then, the first valid value for $b$ is $13318$.