possibility to add new shares

[gryphius]

Thank you for this library!

Would it be possible to add a function to add new shares to an existing pool without modifying the existing shares? i.e. something like

def add_new_shares(existing_shares,number_of_new_shares):

From what I've read on sssa, this should theoretically be possible. But so far my math skills have failed me trying to implement this myself. I don't understand if I would need the original values from https://github.com/SSSaaS/sssa-python/blob/master/SSSA/sssa.py#L17-L20 for this to work so I can pass them to evaulate_polynomal and if so, how I have to reconstruct them from the shares.

[cipherboy]

It should definitely be possible to create new shares if you know the existing data. The issue is that while you can add shares, you can't revoke shares and you can't change the existing threshold.

And I don't think you need those lines, I think you need to be able to reconstruct the original polynomial. My 2c from what I recall. :-)

[cipherboy]

To clarify, I think it is 1) reconstruct original polynomial, 2) generate new random points on polynomial.

You'd have to increase the degree of the polynomial in order to increase the minimum number of shares.

PRs welcome.