Two years ago, having completed the overhaul in my apartment, I decided to install a smart lock on the new front door. Quite quickly it turned out that none of the models available at that time does not fit my quite ordinary metal door. After discussing this "discovery" with one of my friends, we decided to correct this fatal flaw and, as it should in such cases, made another clever castle.
Before we go on to the story of our creation, That such unusual in the Russian doors, and at the same time to draw your attention to other moments, which you need to know about when choosing an intelligent castle. And we will begin with the answer to the main question.
What is a smart castle for?
It seems that the answer to this question is obvious: to get rid of the keys. At least that's what it seemed to us when we first started developing our device. But the first tests showed that if you simply replace the keys with a smartphone, then the benefits of this will be a little: being near the door, it is much easier to unlock or lock it with a key than tapping on the button in the mobile application that you still need to start by unlocking the smartphone. Of course, the possibility of remote control of the door itself can be very useful (for example, to unlock the door of your beloved mother-in-law without getting up from the sofa), but you will most likely not be able to use it.
To become a truly useful device , An intelligent lock should relieve you of most daily manual manipulations with the door. That is, a really clever "smart castle" should – like a doorman in a decent hotel – lock the door for you when you leave the house, and unlock it when you go back.
Despite the name, a typical smart castle is not a castle. Very often this is just a "patch", which is installed on the inside of the door over the turntable or key of a conventional door lock. This pad does not contain a locking mechanism, but can only rotate the key or turntable in a conventional door lock. Of course, there are models that are full-fledged locks (for example, Samsung SHP-DP728), but since the dimensions of the mortise part of the door locks are not standardized, you are unlikely to be able to replace your usual door lock with clever ones – the holes just will not match. But an intelligent "key driver" can theoretically be installed on almost any door, although in reality everything is a little more complicated.
American dead bolt
If you live in Russia, then most likely in your front door there are two locks – cylinder and lever – each of which is locked / unlocked when turning the key for two or even three turns. And most smart locks are compatible only with Deadbolt type door locks. Deadbolt – this is a heck, which is unlocked from the outside and locked with a key, and inside – a turntable. This latch is fully extended / retracted when the turntable rotates by 90-180 °.
Deadbolt-type locks are common in the United States, to the market of which, apparently, the creators of smart gadgets are primarily oriented. As a result, many "key switches" (for example, Sesame, Lockitron and August) are simply unable to turn the key or turntable more than one turn, or so deeply integrated with the Deadbolt mechanisms (such as Schlage Sense and Kevo) that they can not already be Called "overlays", and it is almost impossible to use with any other types of door locks.
Management via BLE and the Internet
Generally, smart door locks are controlled via Bluetooth Low Energy (BLE) via a mobile application. Devices with WiFi support, ZigBee and Z-Wave are also found (for example, RemoteLock and Yale), but BLE is still the leader. This is a very simple explanation: most modern smartphones do not have built-in support for either ZigBee or Z-Wave, and energy-intensive WiFi is not used because mostly smart locks are powered by batteries.
Many smart key manufacturers allow you to manage your devices not only Through BLE, but also through the Internet. Usually it requires a special "bridge", which simultaneously connects both to the smart lock (via BLE), and to your home network (usually via WiFi). As an example of such a bridge, one can mention Nuki Bridge, which "Internetizes" the clever Nuki lock (which, incidentally, is one of the few "key switches" that can be installed without difficulty on most of our doors).
As we said, all the smart locks known to us are powered by batteries. There are two reasons for this. The first is the ease of installation: you do not need to think about how to build a cable to power a smart lock. The second is the longevity of the batteries: they usually need to be replaced only once or twice a year, and any decent smart lock will warn its owner about the need to replace the batteries in advance. Nevertheless, many are still afraid, as if in case of what they did not have to open the door with the "Bulgarian". And we must admit: they fear not in vain.
Regardless of whether your smart battery is powered by batteries or from a network with a backup power source, you may find yourself in a situation where when you are outside the locked door, you can not open it with a smartphone, for example, because its battery is low, Or because the lock has failed, or, finally, just because you lost the smartphone.
To avoid an unplanned replacement of the door, it is recommended to install an intelligent lock only so that you can unlock the door with a key in any non-standard Situation. The key itself need not always be with you, but as with the loss of the key from a conventional lock, the spare key must be somewhere nearby (neighbors or near relatives or friends). For the same reasons, a smart lock designed for a Deadbolt type lock is strictly not recommended to be installed over the night turntable, which can not be opened with a key from the outside.
My house is my fortress
Smart locks are installed not in order to increase the breaking resistance of the door (there is, for this, a separate class of devices – electronic latches of concealed installation, for example, Titan), but in order to make the house more comfortable. For comfort, you have to sacrifice security: any intelligent "controlled by the air" smart lock is always another potential vector of attack, which the burglar can try to use to open the door. Whether he gets it or not – depends on how well the creators of the castle took care of it. Of course, all smart locks use authentication and authorization tools, and encrypt all transmitted traffic, but as practice shows, vulnerabilities in smart devices are still found from time to time.
Separately, we should talk about the safety of the BLE itself, which, as we recall, Is the most common way to manage smart locks. Unfortunately, all the "usable" security modes offered by the BLE standard up to version 4.1 inclusive are vulnerable. Therefore, many smart device manufacturers implement the necessary protocols and algorithms for protecting the wireless connection on their own.
Other vendors are limited to supporting BLE Secure Connections – Numeric Comparison. This is a new standard security mode, in which all data is encrypted with the AES-128 algorithm, and the encryption key is generated using the ECDH algorithm, with verification through an independent channel (similarly protected secret chat in the Telegram messenger). This mode appeared in BLE 4.2, and at the moment there are no vulnerabilities in it.
Smart Castle Dooris
Now that you know almost everything about smart locks, it's time to introduce our creation to you – the intelligent Dooris lock. Doris is a typical "key driver" for a cylinder lock. Using a special screw clamp, it is attached directly to the cylinder of the lock and, if necessary, completely removed. Dooris can turn the key or turntable as many times as necessary to unlock and lock your door. Eats a smart lock from two batteries like CR123A. They will be enough for about a year, if on average you will leave the house 3 times a day (and, accordingly, as many times to return back). The lock is controlled via BLE 4.2 in the Secure Connections – Numeric Comparison mode using a mobile application for iOS or Android.
The Dooris mouse is the SoC nRF52832, to which several sensors are connected: magnetic sensors allow to determine the position of the turntable with an accuracy of 90 °, the accelerometer – The fact of opening and closing the door, and the sensors of current and voltage – to monitor the consumption of motors and the discharge of batteries.
In our castle there are two motors: one unlocks and locks the door, and the second engages and disengages the gears of the first gear. This is necessary so that at any time you can use the key or turntable without any discomfort, that is, without having to overcome the resistance of the reducer. All gears are made of metal, and the body is made of ABS plastic. In order to avoid friction of the plastic assemblies against one another, a bearing is provided in the lock.
While shooting the video, we ran Dooris manually, but as it was said at the beginning, it is better to use the "doorman mode" in which the smart lock locks / unlocks the door itself. Now we will tell you how this mode works.
When you leave the house, you unlock the door with the help of a turntable. As soon as you go outside and slam the door, Dooris learns about it with the help of an accelerometer and will lock the door a few seconds after slamming. Delay is needed to give you the opportunity to make sure that the smartphone is with you.
If you leave the house and you leave the door for more than 30 meters (determined by monitoring the geozones), then upon returning back The mobile application will unlock the door as soon as it receives the iBeacon signal from the smart lock. This will happen about 10 meters from the door, and when you approach it, you will only have to open it. As soon as you enter and slam the door, it will be locked automatically (the same as when leaving the house).
We must admit that in reality the "doorman's regime" does not always work so smoothly. For example, due to the peculiarities of the iBeacon-scanner's operation in smartphones, it may happen that going to the door, you still have to wait a bit before your smartphone "hears" the iBeacon signal and opens the door. Also Dooris can mistakenly lock the door while it is open, if you definitely swing the door, while tapping it at the same time.
We tried to take into account all such moments, and at least rule out situations when, due to any mistake, the door Remained unlocked. But even if we missed something or did not do it well enough, if you want, you can always fix it – the source code of the software part of Dooris will be open (we will publish the source code as soon as the first lot of our smart locks is ready)
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We want to launch Dooris into mass production, but first we need to understand what demand our product will use, and who, if not you, dear readers of SurprizingFacts, can help us the best in this. What do you say: would you buy a clever Dooris castle for 9400 rubles? If so, we are looking forward to your pre-orders (we do not require money ahead). In any case, we will be glad to hear your opinion about our creation and answer the questions.