A nice introduction.

It might be good to go into more detail about why it doesn't take n steps to calculate E given A, given that n is very large.

Instead of calculating one addition at a time, A + A + A + A + ..., the key generation will compute using repeated doubling, for example if we want to compute 130A then we can calculate it as

130A = 2(A+2(2(2(2(2(2A))))))