Quote from: digaran on Today at 12:19:05 PM

Quote from: ing1996 on Today at 10:26:34 AM

hello everyone! You can explain what happens when multiplying

Code:

7fffffffffffffffffffffffffffffff5d576e7357a4501ddfe92f46681b20a2

by an odd key.

Download and run this java calculator, it's very slow and heavy but it's good for manual calculations which is why you can only do manual calc with it.
https://github.com/MrMaxweII/Secp256k1-Calculator

Select scalar on both sides, and place private keys in hex format, then select * , + , - , ÷ , and see for yourself what would be the result.

What you should consider when dividing an odd key, dividing any odd key by 2 will always give you .5 ( point 5, half ), anything on the left side of the point . Is your actuall result no matter if you are dividing by 2 or any other number, but for example we use 2, and anything on the right side of the point . Is a 2^255 + key, we don't want that, so we subtract that from our result to get the actual answer.

3 divided by 2 = 1.>5 < this 5 here means half of n, so if we subtract it from 1.5, we will get 1, our actual result.

Now lets make it a bit difficult, let us divide 7 by 3 = 2.33333333333333333333333333333333333333333333333333333333333333333333333333333 3333333333333333333333333333333333333333333333333333333333333333333333333333333 3333333333333333333333333333333333333333333

Now to get the n/33333........... more 333333..... etc, no need to do any complicated calculation, we just divide 7 by 3 mod n to quickly get the result, then we subtract it from the result to get our key.

Never mind all the above, I have something to twist your minds, take the following key and double, divide, do many other things with it to get really confused about how EC works. 😂

Introducing to you 2^256 of secp256k1

Code:

14551231950b75fc4402da1732fc9bebf

Try multiplying it by 2, 3, 4, 5 etc as well as dividing it, this little sucker is hiding it's half under the ground!

Thanks for the info bro. I use this calculator, it works great! And how do we subtract half of n from the point X and Y coordinates?, or do we need to get the coordinates x, y from half of n? (if there is, then what are the coordinates of half of n). Or was the subtraction just an example to show so that I would understand?.