Digital entrance Options

The following is a (possibly non exhaustive) set of options to secure the entrance to the building and our own space. We have tried to come up with pro's and con's.


Many of the pro's and con's are self-explanatory but some deserve a little clarification:

  • deniability towards other renters: The hackerspace is likely to hand out a significantly larger number of keys than the other renters (that typically have one key holder per room). Therefore it would be nice to be able to show (but probably not legally prove?) that it was not one of our keys that was used to enter the building if ever something gets stolen from another room in the building. In response it has been argued that this only applies to the hypothetical situation where there was no signs of breakage at the outside of the building but there was on the inside. Also: other renters have locks on their internal doors which should be enough and it is not our problem or our responsibility to prove what happened to our keys in an environment where many keys are probably already circulating.

  • revocability: an advantage of digital keys is that they can be revoked. It should be noted that we are already circulating a number of metal keys that will remain usable forever, so only access can be revoked from people who join later or who faithfully hand over all their metal keys once the digital locks are in place.

  • Anonymous access: this can be either a pro or a con. In some systems access is inherently anonymous or anonymized by the implementation. Keep in mind that anonymity is only guaranteed so far as you trust the impolementation and that there are other ways to identify you than by your key so it can be argued that we don't need to protect against attack vectors that are more complicated than putting a hidden camera somewhere.

Description of the available options

  1. nothing digital, metal keys everywhere: This will require two keys per user since we have one for building access and one for space-access. This will cost about 5 euros per key at the moment but we can probably get cheaper keys if we order blanks and copy ourselves.

  2. digital locks as proposed by SA007 and cyberghost: This includes keyreaders at 3 doors. Current cost estimation is 350 euros including 40 keys. Extra keys will cost 5 euros each later. Maybe we can go cheaper for the locks. Keys are in theory identifiable but we implement it such that no logs are kept.

  3. Same as above with minimal tracking: Logs of which key is used are kept for some time but not published. Also the mapping between key ids and real names is restricted to a small number of trusted admins. This data could even be encrypted such that only n out of m admins can access the data together.

  4. Digital locks with ring encryption (as proposal by stf): It is not clear how this technically works. Can this be done with iButtons or does it require special hardware? Is hardware and software needed for this available and how much would it cost?

  5. Metal keys for building, pincode lock on space door: This is an upgradable temporary solution that can be upgraded to ibuttons later and even later be extended to others doors without wasting too much resources (only the keypad). This would probably cost around 50 euros. The pincode can change so access to the space can effectively be revoked. Access is anonymous.

Pro/Con matrix

Criteron/Option 1 2 3 4 5
Fast to implement immediate several weeks several weeks unknown few weeks
Price low expensive expenses expensive? intermediate
anonymous access completely as far as you trust impl. as far as you trust impl. & admins as far as you trust admins completely
key can be copied yes no no no outside, and inside temporarily
revokeable no yes yes yes only inside
trouble in case of persona non grata high low low low medium
number of tokens to carry around 2 1 1 1? 1
deniability towards other renters bad good good good bad
migratable to next space maybe half likely likely likely likely half
possibility to 'buzz' guests in no yes yes yes no
cost per extra key high now, could be low medium medium unknown low
time dependent access no possible possible probably impossible no
power outage resilience high several hours several hours several hours high
liability in case of malfunction? no don't know don't know don't know no
could there be trouble with insurance? yes yes yes yes yes
implementation readily available yes yes yes don't know yes
ease of use medium good good unknown medium
expendable in future yes