Monocypher 4.0.3, vendored UNMODIFIED (REPO_DESIGN.txt section 1a).

  monocypher.c, monocypher.h                    from src/
  monocypher-ed25519.c, monocypher-ed25519.h    from src/optional/
  LICENCE.md                                    BSD-2-Clause or CC0

Source: monocypher-4.0.3.tar.gz, fetched 2026-10-06 from both
https://github.com/LoupVaillant/Monocypher/releases/download/4.0.3/
and https://monocypher.org/download/ ; identical, sha512
40904ada5c7ee4f7741733e38b69a30a4b0561cbffba5ffe7c2dce16136d540251ec0d9056ff606510d3b5b708fb8a40db7e0870d4a0b2dc17ba2bfb880f8965

Only Ed25519 (with its SHA-512) is used, through src/sign.c. Never
edit these files: replace them with a newer release, and update this
note.
