Garage doors

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Sep 30, 2020
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Been thinking about garage doors, and these aren't known for secured devices. Think the first ones would work as long as you sent a signal at the correct frequency. Then they used a code, but think it was rather hackable.

Considering that cpus are cheap and ubiquitous, these should allow a challenge and response using something like pki. Maybe a rpi, but we have learned that security is nontrivial. Besides SN has highlighted how car remotes are rather insecure. So was hoping for a commercial solution

Found one, but the first article was about how they had pwned it lol At least the company had been responsible and fixed it.

 
So was hoping for a commercial solution
A commercial solution for what? If you're considering discussing a commercial tool to hack garage doors, that content is explicitly NOT allowed nor wanted here. There are many other places for black hats to do their nefariousness.

If you want a more secure opener, that part is easy. An RPi on your network (wired hopefully) could be connected to from your cellphone in a number of ways. You securely send a message to the RPi and then it opens/closes a relay, which works just like the buttons that most garage doors already have. (You could probably wire the RPi in parallel to that very button. I've seen a plan for this done by someone in the past, but I don't recall where. I'm sure Google can help you out if you're interested.
 
I would suggest, rather than WiFi, use BTLE instead, as that is both local only, thus no need to have a network connection to use it, but is also limited in range, so you have to be close to it. Simple enough to not use the default pairing codes, and instead use another 4 digit number, plus also only use the BT connection to generate a link, and regard it as non secure, and use that link to set up a much more secure link, that uses some crypto, preferably a good secure one using EC crypto, and a PRNG on the door side to keep on generating random numbers, and a private public key on both sides, so you can get a link set up, then use that to compare key hashes, and make a tunnel in the tunnel, which them can encapsulate the 8 commands you need, open door, close door, light on, light off, open part way, close part way, and 2 for holiday mode to enable and disable the inside convenience override switch. Might take a second to set up the link each time, but a lot more secure than a KEELOQ code remote these days, which is known to be broken, but still in widespread use.
 
I would suggest, rather than WiFi, use BTLE instead, as that is both local only, thus no need to have a network connection to use it, but is also limited in range, so you have to be close to it. Simple enough to not use the default pairing codes, and instead use another 4 digit number, plus also only use the BT connection to generate a link, and regard it as non secure, and use that link to set up a much more secure link, that uses some crypto, preferably a good secure one using EC crypto, and a PRNG on the door side to keep on generating random numbers, and a private public key on both sides, so you can get a link set up, then use that to compare key hashes, and make a tunnel in the tunnel, which them can encapsulate the 8 commands you need, open door, close door, light on, light off, open part way, close part way, and 2 for holiday mode to enable and disable the inside convenience override switch. Might take a second to set up the link each time, but a lot more secure than a KEELOQ code remote these days, which is known to be broken, but still in widespread use.
Agree about using BT, and it's being an unsecured link. Don't think a radio solution would work, since most would need a stronger cpu. Besides BT would make using a phone easier.

The magic would need to happen behind the link. Had thought about pki, but you are right that it would need a private key on both ends.

Not sure you need that many commands. A simple light sensor or even time of day (sun calculation?) should be enough to turn a light on.

Being able to open the door would be useful, and something I hadn't thought of. Guess that since you already have a communication link, it should provide access to all the other functions (disabling the buttons, logs, etc).

As a bonus, being an unknown system, there would be fewer options for a hack, since someone would need to spend some time figuring it out.

ismartgate.com looks interesting (especially after fixing their vulnerabilities). Uses wifi though it can work without using the internet. If it acts as a client, it wouldn't advertise itself unlike using BT (are there silent bt clients?). Wonder how they authenticate and verify their clients?
 
I'll admit to not reading every word of this thread. I just skimmed it. But, here are a couple of suggestions for making a more secure garage door opener. First, the most secure thing of all is something that's not wireless. You can get a wired physical keypad and manually enter a multi digit code on it to open the door. The other option is a wired key switch. If you want wireless, short range is definitely better. I don't know if it was mentioned in the thread, but things like Zigbee and similar have security problems as mentioned by @Steve in the past. You could have your remote connect to your WiFi via WPA encryption and communicate with something inside the house. That depends on more stuff inside the house working to open the door. It also makes the remote more complex. You could possibly use a phone as a remote. You could also use an optical encrypted infrared link, with no RF at all. If there's a power glitch, I'm not sure I'd trust a Raspberry Pi on the inside to reset properly. You might want to use an Arduino, which is more likely to recover properly once power comes back. If not, you could run a Raspberry Pi on a USB battery bank to prevent the power failure issue. It's harder to use complex radio protocols on Arduino. You could always put a physical keypad or key switch in addition to the remote control system. That way, if the remote doesn't work, you can still manually open the door. I think maybe the commercial garage door opener makers are getting better at security, but haven't studied the issue. Just random thoughts. Hope it helps.

May your bits be stable and your interfaces be fast. :cool: Ron
 
A note on a UPS if going the electronic route. I have a Raspberry Pi that stays up and online 7x24 and put a Lithium based UPS on it in case of a power glitch. The UPS had a number of 5 and 12 volt outputs, and from occasional testing it would keep the PI, an external 4TB USB HDD (a spinning NAS type), and a small cooling fan running a couple hours with no problem, a bit over 8 hours by actual test. My occasional tests were only around 2 hours not to stress the batteries. After maybe a year I did my occasional disconnect from AC and everything came immediately crashing down. I bought a second UPS, same one, and again in about a year everything came crashing down, except this time it corrupted something on the disk.

I now bought a second lead acid based UPS. The first lead acid one is a few years old now. I may have just picked a badly designed lithium ups, but be sure to read reviews on a UPS, especially a lithium based one. A 'glitch' in power without a UPS may result in a Pi that will not come back up. If it powers or shuts down a complete removal and restore of power is needed for it to reboot. If wifi is going to be used in the system the router may also need to be on UPS in case of an extended power outage. When it comes to locks, my personal preference leans toward a mechanical solution- but that's just me.
 
corrupted something on the disk
This is, unfortunately, a common Pi problem. The PiKVM found a supposed solution, which is to run the Pi in "read only" mode. When you want to update it, you need to enable writing to the SD card, which will disable again after a reboot. You may want to look into such a thing if you want a more reliable Pi.

If you're building something new, maybe a Raspberry Pico is better. It doesn't have a runtime writable file system as far as I know, and would be even lower power for something so simple. The downside is that networking is not necessarily included, so you need those skills to add a NIC or WiFi device.
 
everything came immediately crashing down

I've found out the hard way that the batteries in lead acid UPS's die every few years. I have a ups that's currently inoperative because of that. There are several online battery sources and, if you buy lead acid batteries, you want ones from a reputable company that were manufactured recently. Even if they don't die, they lose capacity. You have to do a load test a couple of times per year, which almost nobody does. APC Smart UPS's periodically do their own load test for a few seconds then recharge the battery.

I haven't used lithium UPS's per se, but a normal USB battery bank, which generally has lithium polymer or lithium ion batteries inside, might power the Pi for a while. It depends on the capacity of the battery bank and also which output plug it has and which Pi is in use. It might require USB C to get enough current. You also want nice beefy USB power cords with heavy gauge wires rated for 2A or 3A or whatever. Most USB cords are not beefy. Also, an SSD will draw less power than a HDD. Most UPS's have to "transfer" to battery power and there's a "transfer time" of a few mS before that occurs. The Pi could fail even if the UPS is working. It might be possible to put a buffer capacitor on the Pi's 5 V source, but this could make the power supply think the output is shorted if it's too big. Some USB battery banks can charge and output at the same time. In that case, there is no "transfer" and the output is always hot. Some, usually expensive, UPS's can do that too.

corrupted something on the disk.

Linux computers generally hate power loss while hard drives are mounted.

May your bits be stable and your interfaces be fast. :cool: Ron
 
Unless you have a large pin, not sure a keypad would be safer than a good pki system. Since each user would have their certs, it would make authentication and revocation easy. Not sure most people will like to remember a 12 digit pin lol

Indeed you would like it to be as low power, so the neighbor can't spend the evening trying to figure out how to break in. Zigbee, z-wave and the other radio standards need a transmitter and are not as convenient as your phone. That limits you to wifi or bt. Using wifi makes it invisible since it could use one of your networks. Besides you should be running a separate system for your iot. Even if people get into your network, they would still need to be able to send commands to the unit, and that would require the certs.

Not sure you need a ups for this. The motor would be out during an outage. You could have a battery backup for the cpu. You could add a wd to reset the unit if it isn't working. Not sure arduino is more resilient than a rpi, as had some that need manual resetting. Maybe it is just the code on these.

maybe the commercial garage door opener makers are getting better at security
that is the question. Doubt anyone testing them checks to see how secure the unit is.


When it comes to locks, my personal preference leans toward a mechanical solution
Agree, but a garage door opener makes no sense without a remote

APC Smart UPS
They used to make a unit to which you could connect a car battery. Would keep a computer running for most of the work day. Kind of important since it was the time clock.
 
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I've used small Li power banks to power a Pi, mostly a less power hungry A1+. If I remember the capacity correct a 10AH bank would keep it running nearly 4 days. The program I was running 'slept' around 45 seconds out of 60 so it wasn't doing a whole lot of processing, and aside from a sense HAT nothing was connected to it. I started to add a timer into the program to gracefully power it off before the battery gives out.

I haven't looked lately but I have checked for a power bank that would output and charge at the same time to use as a UPS but didn't find one at the time. I should check again, it's been a while.

My 2 small current UPS are Tripp-Lite ECO versions. They have software that can run a periodic battery check but I don't keep a computer connected to either to run the program. There are probably better ones out there, but in part I chose Tripp-Lite due to it's reputation. More so I have a 20+ year old Tripp-Lite APS (essentially a UPS since it has an inverter, maintains a float voltage, and charger) that's been chugging along nearly non-stop since I bought it. I keep 2 deep cycle batteries on it so it is not exactly portable like the smaller units. On occasion I've brought the computer to it.
 
While you're considering backup power (well really power reliability) for a computer to operate the garage, you'd also want to consider the openers themselves. (Or at least one of them.) If you have any sort of frequent power unreliability, then you will no doubt want to be able to have a solution that will work (at least once) when the power is out.
 
power reliability

Ditto that. Also consider surge protection. I live in GA, which has the 2nd highest incidence of lightning in the country. I lost 2 garage door openers and a nice amplifier once to a lightning storm. It's also not a bad idea to learn to use the manual pull rope on the garage door in case you have to open a garage door by hand. You DO have a manual pull rope, right? Opening it is easy, although garage doors without power can be heavy. Closing it and re engaging the mechanism may not be. That assumes, of course, that you have some way to get into your house other than through the garage, since the pull rope is inside. Some houses have a handy entry door for humans near the garage doors. My house, unfortunately, does not.

May your bits be stable and your interfaces be fast. :cool: Ron
 
have a 20+ year old Tripp-Lite APS
Those with external batteries work great. However, the residential ups aren't too good, after a few long outages the batteries don't hold much of a charge.

Have the regular main door as backup lol. Don't seem to find how much current these things need to start. Since they go on a regular 15A outlet, then 15-18A? So maybe a 2.2kVA ups?


Also consider surge protection
Had a few failures due to lighting. However, the surges came through other than power lines (phone, cable, etc.). Added a hefty surge protection system to the main panel (inductors, spark gaps, and varistors), and extra on the phone lines. However, if you get a direct hit, almost nothing will protect you