QuickMaths for Onions: Linear Construction of Sphinx Shared-Secrets



Summary:

The lightning-onion repository has been upgraded by Conner, who has developed a linear algorithm that reduces the total number of scalar multiplications. This optimization results in an 8x speedup and uses ~70% less memory. The implementation used a quadratic algorithm to iteratively apply the intermediate blinding factors, which was pointed out by roasbeef. Conner's PR to lightning-onion provides a description along with the modified source code. The updated output has been verified against the BOLT 4 test vector. If there is interest, Conner can update the example source in lightning-rfc. Links to the lightning-onion repository, the PR, and the BOLT 4 test vector are provided in the context.


Updated on: 2023-05-24T18:59:49.237473+00:00