浏览器中的大数字算术，速度快得令人怀疑？

Question

I am trying to learn Diffie-Hellman, and the reason for its security should be because the computations needed to brute-force it should be so expensive that it would just not be worth it. However typing

(2n**2048n-1n)%(2n**2048n)

in Google Chrome gives an instant result. How come?

Answer 1

2n**2048n is "only" 617 digits in decimal:

% isn't a particularly difficult operation, even on a pair of numbers that large.

I think it's the sheer number of computations, not the difficulty of one of them, that's the key thing in Diffie-Hellman (though I have to admit not being a crypto guy).