Merge branch 'master' of gitlab.stusta.de:stustanet/spacelock

board/README.md

+# Board design
+
+Printed circuit board with all the electrical components.

database/README.md

+# Access Database
+
+* Grants door access.
+* The only trusted software component.
+
+Needs PostgreSQL.

database/setup.sql

+-- spacelock database
+--
+-- creates access tokens, returned by function `gen_token(accesskey)`
+--
+-- (c) 2019 Wolfgang Walter <wolfgang.walter@stusta.net>
+-- (c) 2019 Michael Enßlin <mic@sft.mx>
+-- (c) 2019 Jonas Jelten <jj@sft.mx>
+
+
+-- we use plpython
+-- the user loading this file needs superuser access,
+-- because the loaded python is untrusted code.
+do $$ begin
+	create language plpython3u;
+	exception
+	when duplicate_object then null;
+end $$;
+
+
+-- secret signing key, shared with the door chip
+create table if not exists signer (
+	id bigserial not null,
+	secret text not null
+);
+
+
+-- permission definitions for door users
+create table if not exists permissions (
+	id bigserial primary key not null,
+	description text not null,
+	key text unique not null,
+	valid_from timestamp with time zone not null,
+	valid_to timestamp with time zone not null,
+	active boolean not null
+);
+
+
+-- token creation log
+create table if not exists log (
+	who bigint references permissions(id),
+	token text not null,
+	stamp timestamp with time zone default now()
+);
+
+
+-- message signing in python, because we can
+create or replace function sign_message (
+	signing_key text,
+	now_timestamp double precision,
+	validity_window_size int,
+	message_type int,
+	description text
+) returns text as $$
+	import base64
+	import hmac
+	import struct
+
+	message_blob = struct.pack(
+		'<qqB',
+		int(now_timestamp) - validity_window_size,
+		int(now_timestamp) + validity_window_size,
+		message_type
+	) + description.encode()
+	signing_key_blob = base64.b64decode(signing_key.encode())
+
+	signature = hmac.new(signing_key_blob, msg=message_blob, digestmod='sha256').digest()
+	combined_blob = signature[:16] + message_blob
+	return base64.b64encode(combined_blob).decode()
+$$ language plpython3u;
+
+
+-- token generation, this is the entry point for untrusted users
+-- this function will be executed in setuid-mode!
+-- to grant access, use:
+--   create role spacelock;
+--   grant execute on function gen_token to some_insecure_user;
+create or replace function gen_token (permission_key text)
+returns text as $$
+declare entry permissions%ROWTYPE;
+declare now_time timestamp with time zone;
+declare signing_key text;
+declare token text;
+begin
+	select now() into now_time;
+
+	select * into entry
+	from permissions
+	where
+		key = permission_key and
+		active is true and
+		valid_from <= now_time and
+		valid_to >= now_time;
+	if entry is NULL then
+		return NULL;
+	end if;
+
+	select secret into signing_key from signer order by id desc limit 1;
+	if signing_key is NULL then
+		return NULL;
+	end if;
+
+	select sign_message(
+		signing_key,
+		extract(epoch from now_time),
+		300,  -- 5 minutes token validity
+		0,    -- message type 0: open door
+		entry.description
+	) into token;
+
+	insert into log (who, token, stamp) values (
+		entry.id,
+		token,
+		now_time
+	);
+
+	return token;
+end;
+$$ language plpgsql
+security definer;
+
+
+-- aand we're done!

mount/README.md

+# Door mounting parts
+
+use `openscad`.