16.2, due on November 28

1. (Difficult): Half the numbers mod p are squares? Really? How do we know that?

Also, how can n*A = infinity? In fact the whole section on attacks for discrete logarithms for elliptic curves is fuzzy, especially because I really never understood the index calculus attack.

And, why do we take m=floor(x/K) instead of solving the equation x=mK+j like we normally would?

2. (Reflection): Just so I can solidify, when encoding using an elliptic curve we can make the probability of failure to encode the message as small as we would like. That's nice.

Lastly, elliptic curves are still very strange to me.