Using the LibHydrogen zip produced by this makefile for Arduino Nano failed because impl/gimli-core/portable.h wasn't packaged in the zip.
@@ -25,7 +25,8 @@ SRC = \
impl/random.h \
impl/secretbox.h \
impl/sign.h \
- impl/x25519.h
+ impl/x25519.h \
+ impl/gimli-core/portable.h
all: lib package