Krux DIY Hardware Wallet (Unofficial)

[n0nce]

How about secure elements? Is any of these SoCs protected against just reading out its flash contents through a debug port or desoldering a flash chip from the PCB?

Odudex can correct me if I am wrong, but I think everything is erased from Krux once you turn the power off, so there is nothing to read and copy.
Than you have to load seed phrase each time you turn the power on, best with QR code scan, but it can be done manually.
That is why we don't need to have or trust secure elements, and one of the reasons I like Krux.

Sorry, my mistake! I was mixing up projects.. There are a few DIY hardware wallets by now. Glad to see it, though.
Unfortunately, keeping a QR code with me and making sure nobody takes a picture of it, I don't lose it, ... does not fit my usage model for such a device at the moment.

[odudex]

I would recommend not to trust a chip/device alone, things can go wrong in a lot of ways. A physical backup is important. Also, a passphrase can save you in case someone sees the seed.

[dkbit98]

Unfortunately, keeping a QR code with me and making sure nobody takes a picture of it, I don't lose it, ... does not fit my usage model for such a device at the moment.

I understand what you mean, but someone could take a picture of your regular seed words for any other bitcoin wallet
It can be a bit annoying importing QR code seed phrase each time you power on your device, but it can be faster than entering pin code each time you turn ledger hardware wallet.
For people who are making many transactions each day Krux wouldn't be ideal option, but it's much more secure and there is nothing to hack or exploit.

I would recommend not to trust a chip/device alone, things can go wrong in a lot of ways. A physical backup is important. Also, a passphrase can save you in case someone sees the seed.

He has a point, Krux wallet is not for all-in-one solution for everyone, especially not if you are traveling because you have to take QR code seed phrase with you.
Can Krux be used in multisig setup with other hardware wallets?

[n0nce]

I would recommend not to trust a chip/device alone, things can go wrong in a lot of ways. A physical backup is important. Also, a passphrase can save you in case someone sees the seed.

Of course, I even have a topic about this.
https://bitcointalk.org/index.php?topic=5363596.0

Unfortunately, keeping a QR code with me and making sure nobody takes a picture of it, I don't lose it, ... does not fit my usage model for such a device at the moment.

I understand what you mean, but someone could take a picture of your regular seed words for any other bitcoin wallet

I don't need to carry around my seed phrase backups, though. They are in safe locations.
Meanwhile a hardware wallet with secure element can also be left in a less secure location where it is quickly and easily accessible.

Krux is basically an airgapped computer that lets you easily import a cold / offline / paper wallet.
The necessity to protect the (cleartext) seed QR is a pretty huge downside of this system. You can't even know if someone copied it, since you always carry it around in clear text.
While a quick picture of the QR gives the attacker full access, as well as the ability to stay unnoticed, hacking a Passport (or similar) requires it to be gone for hours (to attempt an intensive hardware attack). You are much more likely to notice that.

[odudex]

The necessity to protect the (cleartext) seed QR is a pretty huge downside of this system. You can't even know if someone copied it, since you always carry it around in clear text.
While a quick picture of the QR gives the attacker full access, as well as the ability to stay unnoticed

That's what passphrases are for. You can also write your seed in different ways, formats, number bases, encodings, encrypted, but sure this is not for everyone. Most people should just trust companies and go with mainstream solutions.
Krux has a supporting role in sovereign strategy, it's a Swiss army knife for create and load seeds in a variety of forms and to sign PSBTs and messages, it requiring less trust.

Can Krux be used in multisig setup with other hardware wallets?

Yes!

[dkbit98]

I don't need to carry around my seed phrase backups, though. They are in safe locations.

You don't need to care physical seed phrase backup, but you are doing it in digital form inside secure element.
I agree with you that Krux is not very good as a portable device, but it's good enough as a part of multisig setup and to use it at home.

Meanwhile a hardware wallet with secure element can also be left in a less secure location where it is quickly and easily accessible.

That is fine until someone exploits that secure element, and we already saw that many secure elements are not secure anymore, including ATECC608A that is used in Passport, OneKey, Cypherock, ColdCard Mk3...

While a quick picture of the QR gives the attacker full access, as well as the ability to stay unnoticed, hacking a Passport (or similar) requires it to be gone for hours (to attempt an intensive hardware attack). You are much more likely to notice that.

Good passphrase and multisig solves this problem very easy, but it would be good to see Krux devs making some unique protection methods in future.

That's what passphrases are for. You can also write your seed in different ways, formats, number bases, encodings, encrypted, but sure this is not for everyone. Most people should just trust companies and go with mainstream solutions.
Krux has a supporting role in sovereign strategy, it's a Swiss army knife for create and load seeds in a variety of forms and to sign PSBTs and messages, it requiring less trust.

Do you think it would be possible to have some alternative firmware option for Krux similar like Jade wallet is using with third party server?

[n0nce]

The necessity to protect the (cleartext) seed QR is a pretty huge downside of this system. You can't even know if someone copied it, since you always carry it around in clear text.
While a quick picture of the QR gives the attacker full access, as well as the ability to stay unnoticed

That's what passphrases are for.

How do you enter the passphrase when it has just one button? Or is it scanned in through a second QR code? Of course this wouldn't be an acceptable solution either, since someone could take a photo of that (while you don't notice) or just steal it, as well.

I don't need to carry around my seed phrase backups, though. They are in safe locations.

You don't need to care physical seed phrase backup, but you are doing it in digital form inside secure element.

Exactly: Inside a secure element and not in clear text on an easy to scan QR code. Even if you have a good exploit against the specific secure element, it may take hours or days, as well as obviously lots of money and knowledge, execute it.

I agree with you that Krux is not very good as a portable device, but it's good enough as a part of multisig setup and to use it at home.

Sure! But at that point, it resembles more an airgapped computer than a hardware wallet, for me. Of course it will be hard to draw a line between the two definitions.

Meanwhile a hardware wallet with secure element can also be left in a less secure location where it is quickly and easily accessible.

That is fine until someone exploits that secure element, and we already saw that many secure elements are not secure anymore, including ATECC608A that is used in Passport, OneKey, Cypherock, ColdCard Mk3...

You are referring to this attack, right? https://hackaday.com/2022/11/26/defeating-a-cryptoprocessor-with-laser-beams/
Well, not secure is a bit exaggerated. Have you seen what type of setup and knowledge is needed to attack it, the risks and challenges in that process? It's not comparable to just having the seed on a piece of paper in clear text. Even setting up a passphrase cracking rig will be easier and cheaper for most folks than performing a hardware attack on a secure element. There are also significant risks involved, such as breaking the device / chip while opening and decapsulating the secure element.
Basically, you can compare such measures to physical locks. None is 100% safe, but they are made to discourage an attacker and buy you as much time as possible in case they do decide to try bypassing it. Time for moving your coins / calling the police, respectively.

While a quick picture of the QR gives the attacker full access, as well as the ability to stay unnoticed, hacking a Passport (or similar) requires it to be gone for hours (to attempt an intensive hardware attack). You are much more likely to notice that.

Good passphrase and multisig solves this problem very easy, but it would be good to see Krux devs making some unique protection methods in future.

Do you know how passphrase entry is realized? I believe unless you have a nice keypad like Passport or ColdCard, most people will just avoid using (a sufficiently secure) one.

With that said: I could argue that you could also use a passphrase on your Passport with secure element. Twice as secure; first layer of defense: secure element, second layer of defense: passphrase. Meanwhile when stealing someone's Krux & QR code, there is only the second layer.

[odudex]

Krux smaller devices has 3 buttons, and the most popular, Amigo, has capacitive touch screen. You could check the Android app to have an idea of what we are talking about.

[dkbit98]

How do you enter the passphrase when it has just one button? Or is it scanned in through a second QR code? Of course this wouldn't be an acceptable solution either, since someone could take a photo of that (while you don't notice) or just steal it, as well.

Dude, I don't know who told you about one button, but you are wrong about this, it would be almost impossible to operate any device with just one button, unless it's joystick style  
Small device M5StickV K210 have two buttons I think, and other larger devices that work with Krux code have more buttons.

Sure! But at that point, it resembles more an airgapped computer than a hardware wallet, for me. Of course it will be hard to draw a line between the two definitions.

It's airgapped device.
Computer usually have more functions and it has wider attack surface.

You are referring to this attack, right? https://hackaday.com/2022/11/26/defeating-a-cryptoprocessor-with-laser-beams/

Yes I was talking about this, but previous version of secure element ATECC508A had even bigger issues, so old ColdCard (I think mk2) had to change it very fast.
It's realistic to say that same thing can happen with  ATECC608A and ATECC508B in future, like with any other secure elements, and you can't exactly remove and replace secure element from working device.

Do you know how passphrase entry is realized? I believe unless you have a nice keypad like Passport or ColdCard, most people will just avoid using (a sufficiently secure) one.

Even if you have perfect keypad like Passport you certainly wont write very long passphrase essays, because you still need to enter this each time you use device.

You could check the Android app to have an idea of what we are talking about.

Krux Android App for testing (this is also working on some Android emulators I tried):
https://github.com/odudex/krux_binaries/tree/main/Android

What would be oldest the Android version supporting Krux app?
I have some ancient smartphone device with Android 4 or 5 I think  

[odudex]

Small device M5StickV K210 have two buttons I think, and other larger devices that work with Krux code have more buttons.

Even M5stickV has 3 buttons now. After an update, power button can be used to navigate(go back).
DIY version Dock navigates using a rotary encoder.

-Android:
I don't know how old Androids will handle the app. As the app doesn't require anything fancy I hope it has some wide range of compatibility. I have some cheap, but not old phones to test. If you try let us know if it worked.
- Linux, Windows, Mac
If you have a PC running python, on any OS, by installing some requirements you can also run a very functional simulator from source code. It's a very good to start point to play with Krux code.

[dkbit98]

Even M5stickV has 3 buttons now. After an update, power button can be used to navigate(go back).
DIY version Dock navigates using a rotary encoder.

Yeah I know, but I have to admit that buttons are not very comfortable to use, if anyone plans to use them for entering letters and seed words manually

I don't know how old Androids will handle the app. As the app doesn't require anything fancy I hope it has some wide range of compatibility. I have some cheap, but not old phones to test. If you try let us know if it worked.

I tried using Krux app with Android v4.4.2 and sadly it could not be installed on this old smartphone from year 2015.
It works just fine in any newer smartphone and in android emulators.

[odudex]

Yes, the buttons and small screen don't make a good UX, but as M5stickV was the first Krux device and has its fans for being so tiny it will always get our attention and updates.
Amigo UX, on the other hand, is really smooth, and still has a lot of room for improvements.

I'll see if I find some older phone to check if its possible to build the app for them too.

[odudex]

I tried using Krux app with Android v4.4.2 and sadly it could not be installed on this old smartphone from year 2015.

You may try the last version. It is now compatible with armv7 chips (not only v8). I tested on a Android v6.0, it wasn't working, now it is!

[dkbit98]

You may try the last version. It is now compatible with armv7 chips (not only v8). I tested on a Android v6.0, it wasn't working, now it is!

I just tried latest github version Krux 23.04 BETA_3 Android_0.5 on same old junk Android 4.4.2 and I can confirm it's sadly NOT  working.
Error message I am getting is: There was a problem parsing the package.
This is very old android device so I am not expecting any miracles

[odudex]

I just tried latest github version Krux 23.04 BETA_3 Android_0.5 on same old junk Android 4.4.2 and I can confirm it's sadly NOT  working.
Error message I am getting is: There was a problem parsing the package.
This is very old android device so I am not expecting any miracles

Sorry to hear that, I believe we won't be able to go lower than Android 6.0. But the effort to lower the requirements was fruitful. Thanks for testing!

[dkbit98]

Sorry to hear that, I believe we won't be able to go lower than Android 6.0. But the effort to lower the requirements was fruitful. Thanks for testing!

No problem, sorry for not posting screenshot/video confirmation, it took me only few minutes of testing, and I don't have any other old devices to try, so it could be related only with my device.
I am glad you tried to work on that and remembered to make a post about it in forum

[Lillominato89]

I have to make you my most sincere congratulations! you are the master of DIY hardware wallets! sooner or later I'll try to make a DIY hw, as regards the new European law on the creation of open source codes which will have to be approved on April 26, do you know if there will be problems with the krux repositories?

I am referring to this bill
https://www.european-cyber-resilience-act.com/

[odudex]

Thanks(in the name of all Krux contributors)! I encourage you to build them, but I warn you it is addictive, once you build one you'll want all types
Regarding the law, the way I see it is there's one great thing about Krux: There's no business! No consumers or clients to "be protected". We are just a few nerds having fun with code e general purpose hardware at our own risk. No one asked for trust or money, all we want are scrutiny and ideas to improve our toys

[Meuserna]

Krux smaller devices has 3 buttons, and the most popular, Amigo, has capacitive touch screen.

I'm just replying to say that I love what you guys are doing and I'm very excited about the project.  I have an Amigo on backorder, so I guess I'll be waiting for a while, but I ca't wait to give Krux a try.

Is there a story behind the Krux name?

[kkdao]

Don't think I've came across a story for the name actually. As for your Amigo being on backorder that's too bad. Which site and continent are you ordering from if you don't mind me asking? Usually there is someone somewhere that has them in stock.