mirror of
https://github.com/vitorpamplona/amethyst.git
synced 2026-08-12 01:07:46 +00:00
Claude
ec1833b346
Fixed the wNAF encoding bug and wired it into the verification hot path.
Bug fix: The wNAF encoding silently dropped carry bits that overflowed past
the 256-bit scalar boundary. When a negative digit near bit 251 caused a
carry to bit 256, the extraction window was clamped to 0 bits by
`w.coerceAtMost(maxBits - bit)`, causing the carry digit to be lost.
Fixed by extending the working copy and result arrays to accommodate
carries up to bit (maxBits + w), and using totalBits instead of maxBits
for the window size clamp.
Performance: wNAF-5 (windowed Non-Adjacent Form, width 5) encodes scalars
using signed odd digits {±1, ±3, ..., ±15} with guaranteed ≥4 zero-runs
between non-zero digits. This reduces point additions in mulDoubleG from
~120 (4-bit window) to ~86 for two 256-bit scalars, a ~28% reduction in
additions while the 256 doublings remain the same.
Benchmark improvement for verifySchnorr:
Before: 1,940 ops/s (12.9x vs native)
After: 2,626 ops/s (10.6x vs native)
https://claude.ai/code/session_01BhU63WUe9AhikZxRdw3Lpg