Nice work! I reread the relevant section in BOLT 4 and it is written in a way to suggest the quadratic time algorithm. I have opened a PR to update the recommendation and reference code: https://github.com/lightningnetwork/lightning-rfc/pull/374.
On Fri, Feb 2, 2018 at 6:20 PM, Conner Fromknecht < firstname.lastname@example.org> wrote: > Hello everyone, > > While working on some upgrades to our lightning-onion repo , roasbeef > pointed > out that all of our implementations use a quadratic algorithm to > iteratively apply the intermediate blinding factors. > > I spent some time working on a linear algorithm that reduces the total > number of scalar multiplications. Overall, our packet construction > benchmarks showed an 8x speedup, from 37ms to 4.5ms, and now uses ~70% less > memory. The diff is only ~15 LOC, and thought this would be a > useful optimization for our implementations to have. I can make a PR that > updates the example source in lightning-rfc if there is interest. > > A description, along with the modified source, can be found in my PR to > lightning-onion . The correctness of the output has been verified > against the (updated) BOLT 4 test vector . > >  https://github.com/lightningnetwork/lightning-onion >  https://github.com/lightningnetwork/lightning-onion/pull/18 >  https://github.com/lightningnetwork/lightning-rfc/pull/372 > > Cheers, > Conner > > _______________________________________________ > Lightning-dev mailing list > Lightningemail@example.com > https://lists.linuxfoundation.org/mailman/listinfo/lightning-dev > >
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