Question $2$: Elliptic Curves $(20$ points$)$

Let E$.(2,1)$ bo an ellipilic curve datined over $20.$

a$.$ Please write down the cuble equation of tho given ellppite curvo. $(5$ point$)$

b$.$ Let Point $P$:$(0,1)$ Point Q: $(1,3).$ Calculato the point $R=P+Q.(15$ points$)$

Question $3$: Other questions $(25$ points$)$

a$.$ Usa Squareand$-$Mullply algorithm to calculale $17$ Mo$0$ mod $100$ by hand. $(00$ points$)$

b$.$ Describe the trap$-$dcor one$-$way foncion of the Elcamal algoithm. $(6$ points$)$

c$.$ Breily doseribe how to usa pubtlokey encryption to provdta both conidantiality and authenticalion $(10$ points$)$