oa8signverify/oa8sign

#!/usr/bin/env sh
set -e -u
if ! env -i command -p rm -f "$(env -i command -p mktemp)"; then
	printf '%s\n' "Error: rm could not be located."
	exit 1
fi
cleanup() { env -i command -p rm -f "${tmpfile:-}" || true; }
filename=${1:-}
privatekey=${2:-}
if ! env command openssl version >/dev/null 2>&1; then
	printf '%s\n' "Error: openssl could not be located."
	exit 1
fi
if ! env command ascii85 -h >/dev/null 2>&1; then
	printf '%s\n' "Error: ascii85 could not be located."
	printf '%s\n' 'Suggestion: "gem install Ascii85".'
	exit 1
fi
if [ "${#}" -lt 2 ]; then
	printf '%s\n' "*** oa8sign (v1.0.0)"
	printf '%s\n' "Usage: oa8sign <file> <private.oa8>"
	exit 1
fi
if [ ! -f "${filename:?Error: filename undefined.}" ]; then
	printf '%s\n' "Error: file not found."
	exit 1
fi
if [ -f "${filename:?Error: filename undefined.}.oa8" ]; then
	printf '%s\n' \"Error: "${filename:?Error: filename undefined.}".oa8 exists.\"
	exit 1
fi
if [ ! -f "${privatekey:?Error: privatekey undefined.}" ]; then
	printf '%s\n' "Error: privatekey not found."
	exit 1
fi
tmpfile=$(env command -p mktemp) ||
	{
		printf '%s\n' "Error: mktemp failure."
		exit 1
	}
env command openssl dgst -sha3-512 \
	-sign "${privatekey:?Error: privatekey undefined.}" \
	-out "${tmpfile:?Error: tmpfile undefined.}" \
	"${filename:?Error: filename undefined.}" ||
	{
		printf '%s\n' "Error: openssl failure."
		cleanup
		exit 1
	}
printf '****** BEGIN OA8 SIGNATURE ******\n%s\n****** END OA8 SIGNATURE ******\n' \
	"$(env command ascii85 -w 61 \
		<"${tmpfile:?Error: filename undefined.}")" \
	>"${filename:?Error: filename undefined.}.oa8" ||
	{
		printf '%s\n' "Error: Writing signature failed."
		cleanup
		exit 1
	}
cleanup || true