The weekend of April 4th-5th 2020 we had a remote "Lightning Hacksprint" organized by the ever-excellent Fulmo, one Challenge was related to "Payment Points" (see here; see lots more info about the hacksprint at that wiki) and was based around a new innovation recently seen in the world of adaptor signatures. Work was led by Nadav Kohen of Suredbits and Jonas Nick of Blockstream; the latter's API for the tech described below can be seen currently as a PR to the secp256k1 project here. The output from Suredbits was a demo as show here on their youtube, a PTLC (point time locked contract, see their blog for more details on that).
This blog post is all about this paper by David Wagner from 2002.
This blog is in the category of "a new-ish idea about privacy tech"; like similar previous ones (e.g.: CoinJoinXT) it is little more than an idea, in this case I believe it is correct, but (a) I could be wrong and there could be a flaw in the thinking and (b) it's not entirely clear how practically realistic it will be. What I do hope, however, is that the kernel of this idea is useful, perhaps in Layer 2 tech or in something I haven't even thought about.
The idea of a ring signature (the term itself is a bit sloppy in context, but let's stick with it for now) is simple enough:
How sure are you that the cryptography underlying Bitcoin is secure? With regard to one future development of Bitcoin's crypto, in discussions in public fora, I have more than once confidently asserted "well, but the Schnorr signature has a security reduction to ECDLP". Three comments on that before we begin:
Adam Gibson (22)