Android as a cold wallet

[_act_]

I have noticed that it will be very difficult to make an Android phone to be an airgapped device to set up Electrum wallet. But I am still thinking of finding ways to perfectly make an Android wallet. Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

[BitcoinGirl.Club]

I have noticed that it will be very difficult to make an Android phone to be an airgapped device to set up Electrum wallet. But I am still thinking of finding ways to perfectly make an Android wallet. Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

I don't think it's impossible but perhaps difficult. Assuming your device has no internet. You will need to download the wallet from Electrum.org. Then using a cable, transfer it to your android device. Install it and use it.

For signing a transaction you will need to transfer the signed file to a device which has internet connection so that you can broadcast it.

[Yamane_Keto]

Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

It's not about Android OS but Android is installed on devices that require internet connection like phones and tablets and it's hard to make them air-gapped.

• An intermediate solution is to install https://airgap.it but DYOR
• A better solution is to buy a raspberry pi zero which costs less than an old android phone.

[Mia Chloe]

 I have seen a post like  this some time ago on the beginners and help board so I went back to search for it. HERE IT IS
From what I have understood so far, making an air gapped device can be very difficult especially if you are trying to be very careful making sure that you have totally cut off all internet connections the device has. Personally I think an android won't be as safe an airgapper Device as an old PC technically will be .
This is because of reasons that are quite obvious like being able to remove network components . In an android device you would have to get rid of the the Bluetooth, WiFi and cellular network components and I am not sure yet if it would have any effect on the device.

[ranochigo]

Likely not. Android phones are not designed to function without communication for obvious reasons. You'd have to overhaul the OS completely for it to be a complete airgap. Else, just changing the settings would allow you to connect to cellular or WiFi. Most of the chips are also soldered on and can't be removed easily.

In addition, most wallets are not designed to function with an Android phone without internet connection. You'd be better off purchasing an old laptop, or a Raspberry Pi for it to function as an airgapped wallet.

[NeuroticFish]

I have seen a post like  this some time ago on the beginners and help board so I went back to search for it. HERE IT IS

I also had some years ago the same idea as OP has: to use an old Android phone as cold storage. The topic is here: Old phone as cold storage?
Long story short: while it does work with Electrum, it's not a safe enough setup (at least in theory it can too easy become hot wallet). More technical people than me came with good arguments and convinced me back then against it.
@_act_: take a look in there, I still consider it a good read: Old phone as cold storage?

[LoyceV]

I am still thinking of finding ways to perfectly make an Android wallet. Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

I'm not sure what you're asking here. Usually, when you want a device to be offline, you don't enable any networking. You can't "encrypt" hardware, so there's no "password" to disable either.

Why not use an old laptop? Many people have them piling up by now, and they're quite cheap to buy (although this may depend on your location). For cold storage, you don't need powerful hardware. Ideally, wipe it and install Linux. Install Electrum or whatever you prefer, and you're good to go. If you want to go full-paranoid (which is my preferred setup ), physically remove networking, camera and microphone. Glue the RAM. Encrypt the disk. Set bios passwords. Even better if the disk supports hardware encryption to use on top of disk encryption. Don't get one with built-in SIM support.
I just checked: for €75 or less, I can choose from many laptops with 8GB RAM, SSD and working battery. Those are perfect for the task.

[Hatchy]

This is because of reasons that are quite obvious like being able to remove network components . In an android device you would have to get rid of the the Bluetooth, WiFi and cellular network components and I am not sure yet if it would have any effect on the device.

Yea, that a major reason I don't think a mobile device, not just android. would fit as an air gapped device. Creating an airgapped devices, one needs to eliminate all the network components on the device totally. Such components like those you mentioned are the major thing that makes a mobile device work properly. Removing them might damage the device. Just use an old PC just like everyone has said. It might not even be old if you have a PC you aren't using anymore you can just convert it to an airgapped device by removing all the network components.

[_act_]

I am still thinking of finding ways to perfectly make an Android wallet. Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

I'm not sure what you're asking here. Usually, when you want a device to be offline, you don't enable any networking. You can't "encrypt" hardware, so there's no "password" to disable either.

Do not mind my bad English. I mean that I know that Android can not be perfectly be an airgapped but that can I still make it offline in a way no one can enable the WiFi, network, Bluetooth and others that I have disabled from it like how they can be disabled from the BIOS on laptop. That can I of the WiFi, network and others in a way that only password can make them work again in a way if you want to on any of them, the phone will request for password to do that.

Why not use an old laptop? Many people have them piling up by now, and they're quite cheap to buy (although this may depend on your location). For cold storage, you don't need powerful hardware. Ideally, wipe it and install Linux. Install Electrum or whatever you prefer, and you're good to go. If you want to go full-paranoid (which is my preferred setup ), physically remove networking, camera and microphone. Glue the RAM. Encrypt the disk. Set bios passwords. Even better if the disk supports hardware encryption to use on top of disk encryption. Don't get one with built-in SIM support.
I just checked: for €75 or less, I can choose from many laptops with 8GB RAM, SSD and working battery. Those are perfect for the task.

I even have a laptop which is not working but nothing more than to repair it. Files were too much on it and also updating it makes slower as it was an old laptop. I wanted to install Ubuntu on it when it starts to on and off after I started the process but was unable to complete the installation. I use multisig wallet but the last exchange that was hacked which used multisig wallet gave me concerns. I think it is time the multisig can be used with offline wallet for maximum security. But just that I have a phones which is not really old but I am not using it. It is still working good. Although it is still part of the devices that I used for the multisig wallet.

[LoyceV]

I mean that I know that Android can not be perfectly be an airgapped but that can I still make it offline in a way no one can enable the WiFi

In that case: nobody should have physical access to your cold wallet.

I even have a laptop which is not working but nothing more than to repair it. Files were too much on it and also updating it makes slower as it was an old laptop. I wanted to install Ubuntu on it when it starts to on and off after I started the process but was unable to complete the installation.

Try Tails OS. No need to install it. If it boots, you can use Electrum offline (or through Tor if you give it internet access).

I think it is time the multisig can be used with offline wallet for maximum security.

I never felt comfortable with multisig. It just doesn't feel intuitive enough to me.

[BitMaxz]

I have a Samsung S4 phone with working wifi before removing the wifi and Bluetooth modules with BGA hotair and the unit still works just fine without them.
I also installed Electrum Wallet on that phone but the last version that I use on that phone is I think around 2.9.3 I installed them through the internet data from the sim and then removed the sim card it worked fine before. The only problem is it uses an old version of Android 5.0.1 and no update since 2017 so a new version of Electrum might not work anymore.

I don't know if other phones will work without wifi and Bluetooth modules but you can remove these parts at least tested on Samsung s4 and old Chinese/clone model phones.

If you want to completely remove these modules wifi and Bluetooth hire a phone technician they can maybe able to help you disable it through hardware or software.
I heard for software solution they can turn the wifi&bluetooth driver corrupted with 0 Mac addresses which makes Bluetooth and wifi useless.

Honestly, for me, raspberry pi is still the best option as a cold storage wallet you can make it portable and buy an LCD and camera to use it for airgap.

[AB de Royse777]

I just checked: for €75 or less, I can choose from many laptops with 8GB RAM, SSD and working battery. Those are perfect for the task.

What's wrong with to buy a hardware wallet with this money instead of doing all the hassles to assemble an old broken laptop.

[NeuroticFish]

I just checked: for €75 or less, I can choose from many laptops with 8GB RAM, SSD and working battery. Those are perfect for the task.

What's wrong with to buy a hardware wallet with this money instead of doing all the hassles to assemble an old broken laptop.

A HW is clearly more convenient, however, in most of the cases you have to trust the manufacturer (see Ledger suprise with retrieval of seed, see the new exploit info for any HW if manufacturer is malicious) .

This being said, many will try to make their own cold storage.If you know what you are doing it's better.

[LoyceV]

What's wrong with to buy a hardware wallet with this money instead of doing all the hassles to assemble an old broken laptop.

Ask OP: he wants to go through even more hassles to use a phone

A HW is clearly more convenient, however, in most of the cases you have to trust the manufacturer

Exactly. If I wanted to trust a company with my money, I could just as well use a bank or Bitcoin ETF.

[ABCbits]

Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

Not really, you only can
1. Configure lock screen with PIN password.
2. Deny permission to change connection state to each application.

I even have a laptop which is not working but nothing more than to repair it. Files were too much on it and also updating it makes slower as it was an old laptop. I wanted to install Ubuntu on it when it starts to on and off after I started the process but was unable to complete the installation.

Have you ever checked what caused it? I would speculate either low RAM capacity or broken HDD.

I use multisig wallet but the last exchange that was hacked which used multisig wallet gave me concerns.

Are you taking about WazirX? They're far more likely targeted by hacker than you.

[Yamane_Keto]

If you want to completely remove these modules wifi and Bluetooth hire a phone technician they can maybe able to help you disable it through hardware or software.  

Modern devices come with System on Chip (SoC) so it is easy to remove moblie data by removing antenna but WiFi and Bluetooth may be more difficult and impossible in modern phones. Older versions come with Android versions that are not compatible with most current wallets.

I just checked: for €75 or less, I can choose from many laptops with 8GB RAM, SSD and working battery. Those are perfect for the task.

What's wrong with to buy a hardware wallet with this money instead of doing all the hassles to assemble an old broken laptop.

in some countries, HWs may not be able to be shipped or may be confiscated by customs authorities. Repurchasing them from unofficial retailers is dangerous.

[Findingnemo]

I have noticed that it will be very difficult to make an Android phone to be an airgapped device to set up Electrum wallet. But I am still thinking of finding ways to perfectly make an Android wallet. Is it possible to disable network connection, WiFi, Bluetooth and other means of connection with encrypted password in a way that if you want all these connections to be enabled and functioning again, you will need to disable the password?

Definition of cold wallet, it should be eliminated from connected to internet but you're asking it should remain same so you can install an Electrum on your Android but it won't be cold wallet anymore once you connected to the internet.

Even if you don't want the device to be connected via internet still smart phones are not good choice because you only can attain the level on software level which can be compromised with just a wrong tap so it should be a PC or just go with HW if you seek convenience.

[dkbit98]

I wouldn't suggest anyone to use Android device as a main cold storage, but it's ok to use it as secondary signing device.
There is another interesting cheap alternative called Maix Amigo that is used for open source airgapped Krux wallet.
Price is around $50 and it looks like a smaller smartphone but without any connection except with camera and QR codes.

[DaCryptoRaccoon]

I know it's outside the scope for "android" but this is what I would go for.

https://github.com/usbarmory/usbarmory

build something off the base of this and have your own hardware wallet offline.

Worth a look.

[BitMaxz]

What's wrong with to buy a hardware wallet with this money instead of doing all the hassles to assemble an old broken laptop.

I have this old laptop with a broken LCD and no wifi I can able to connect it to an external monitor it still has some old backup wallets but never been used it as airgap because it is a bit of hassle copying the raw transaction and transferring it through USB flash compared to a two phone that I currently have offline(a device never connected to our wifi) and online device that I usually use for crypto and trading the good thing about this you can just scan QR code in vice-versa when signing a transaction. However, the phone version gets old and Android always has a new version so for me, it's still not a good device for long-term use because the software or wallet might not work properly in the future since wallet software is also developing to support the new Android version.

As I said raspberry pi is still the best option you can reformat the SD card and replace the OS(Tails as a sample) with the latest one and reimport your wallet. No hassle once you already have a camera and LCD/Monitor.