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Mar 26, 2018

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narodnik10:38

Hello everyone, I made a pull request for adding ec_sum to math/ https://github.com/libbitcoin/libbitcoin/pull/922

GitHub

added new function to math/ called ec_sum. Adds a list of provided ec points together. by narodnik · Pull Request #922 · libbitcoin/libbitcoin

Provided unit test. Neccessary for modern privacy schemes which hide sharing amounts. They involve summing points from different curves together: A + B + C. This function provides that functionality.

👍 2

9 replies · James C., narodnik · last Mar 29, 2018

James C.11:58

This is great! I was trying to do petersen commitment (C = rH + aG) with ec math a couple weeks ago in Libbitcoin, and this was exactly what I needed! Previously could only add multiples of Generator points.

James C.12:05

Question regarding "summing points from different curves together", perhaps I misunderstand, is this about summing discrete EC points on the secp256k1?

narodnik14:44

it's exactly what you say. It enables you to add 2 or more points together

narodnik14:48

value_one = [0, 0, 0, ..., 0, 1] G = secret_to_public(value_one) H = ec_multiply(G, some_constant) rH = ec_multiply(H, r) aG = ec_multiply(G, a) output = ec_sum([rH, aG]) (libbitcoin psuedo code)

👍 1

narodnik14:49

well I guess H should be precomputed without some_constant being in the actual code

👍 1

James C.15:12

very cool! homomorphic commitments now possible with Libbitcoin 🙂

(edited)

James C.15:21

I'll add a pedersen commitment example and demonstrate homomorphism in the wiki once its merged.

James C.14:05

https://github.com/libbitcoin/libbitcoin/wiki/Pedersen-Commitments-in-EC-Form

GitHub

libbitcoin/libbitcoin

libbitcoin - Bitcoin Cross-Platform C++ Development Toolkit

James C.14:05

now possible with ec_sum()