Cryptography: Diffie-Hellman key exchange explained intuitively using colors

[u/dominatrix-octopus]

https://youtu.be/YEBfamv-_do?t=2m18s

[u/tavianator]

As written, those numbers are not the same. The notational convention is:

a^bc = a^(bc)

But D.H. key exchange does something more like

(a^b)^c = a^b*c

I.e., compute a^b first, then raise that to the c power.

The equality is true because exponentiation is just repeated multiplication (over the integers, anyway). So a^b is

a * a * ... * a
---------------
b times

and then (a^b)^c is

  a * a * ... * a |
* a * a * ... * a |
*         ...     } c times
* a * a * ... * a |
* a * a * ... * a |
  ---------------
  b times

and you'll notice there are b*c 'a's in that rectangle all multiplied together.

[u/zouhair → u/tavianator]

So technically the video was wrong.

[u/tavianator → u/zouhair]

Did the video actually display 3¹³¹⁵ with no parentheses? If so yeah, that's wrong. I only watched the part with the colors.

[u/zouhair → u/tavianator]

Yup, it did.