lightning-loop: add pkg

pkgs/lightning-loop/get-sha256.sh

@@ -0,0 +1,27 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i bash -p git gnupg
+set -euo pipefail
+
+TMPDIR="$(mktemp -d -p /tmp)"
+trap "rm -rf $TMPDIR" EXIT
+cd $TMPDIR
+
+echo "Fetching latest release"
+git clone https://github.com/lightninglabs/loop 2> /dev/null
+cd loop
+latest=$(git describe --tags `git rev-list --tags --max-count=1`)
+echo "Latest release is ${latest}"
+
+# GPG verification
+export GNUPGHOME=$TMPDIR
+echo "Fetching Joost Jager's Key"
+gpg --keyserver hkps://keyserver.ubuntu.com --recv-keys D146D0F68939436268FA9A130E26BB61B76C4D3A 2> /dev/null
+echo "Fetching Alex Bosworth's Key"
+gpg --keyserver hkps://keyserver.ubuntu.com --recv-keys DE23E73BFA8A0AD5587D2FCDE80D2F3F311FD87E 2> /dev/null
+
+echo "Verifying latest release"
+git verify-tag ${latest}
+
+echo "tag: ${latest}"
+# The prefix option is necessary because GitHub prefixes the archive contents in this format
+echo "sha256: $(git archive --format tar.gz --prefix=loop-${latest//v}/ ${latest} | sha256sum | cut -d\  -f1)"