add encrypting for save files

add libhydrogen for encrypting and decrypting

#9

libs/libhydrogen/Makefile.chibios

@@ -0,0 +1,43 @@
+MCU ?= cortex-m7
+WFLAGS ?= -Wall -Wextra -Wmissing-prototypes -Wdiv-by-zero -Wbad-function-cast -Wcast-align -Wcast-qual -Wfloat-equal -Wmissing-declarations -Wnested-externs -Wno-unknown-pragmas -Wpointer-arith -Wredundant-decls -Wstrict-prototypes -Wswitch-enum -Wno-type-limits
+CFLAGS ?= -Os -mcpu=$(MCU) -mthumb -mpure-code -fno-exceptions -ffunction-sections -fdata-sections -flto $(WFLAGS)
+CFLAGS += -DCHIBIOS
+CFLAGS += -I.
+OBJ = hydrogen.o
+AR ?= arm-none-eabi-ar
+CC = arm-none-eabi-gcc
+RANLIB ?= arm-none-eabi-ranlib
+
+SRC = \
+	hydrogen.c \
+	hydrogen.h \
+	impl/common.h \
+	impl/core.h \
+	impl/gimli-core.h \
+	impl/hash.h \
+	impl/hydrogen_p.h \
+	impl/kdf.h \
+	impl/kx.h \
+	impl/pwhash.h \
+	impl/random.h \
+	impl/secretbox.h \
+	impl/sign.h \
+	impl/x25519.h
+
+all: lib
+
+lib: libhydrogen.a
+
+$(OBJ): $(SRC)
+
+libhydrogen.a: $(OBJ)
+	$(AR) -r $@ $^
+	$(RANLIB) $@
+
+.PHONY: clean
+
+clean:
+	rm -f libhydrogen.a $(OBJ)
+	rm -f tests/tests tests/*.done
+
+distclean: clean