Hi all,

We'd like to bring to your attention our recent result concerning HTLC. Here are the technical report and a short post outlining the main points:

* https://arxiv.org/abs/2006.12031
* https://ittayeyal.github.io/2020-06-22-mad-htlc

Essentially, we find that HTLC security relies on miners being altruistic, or at least myopic. This might be enough for some time, but it took us 150 lines of code to make bitcoind non-myopic.

On the positive side, we discovered an alternative to HTLC that we call MAD-HTLC, which is provably secure -- everyone's best interest is to behave as desired.

We've notified relevant teams in advance.

We'll appreciate any comments.

Best,
Itay, Ittay, and Matan