Using mobile phone as a full mobile wallet

[Charles-Tim]

This could be so hilarious but I just need you to contribute.

If someone has two mobile phones, deciding to use one as a mobile wallet. To me, this is a good idea as one of the phones can be useless. And having in mind to use it as wallet and putting these in consideration.

Having back up of his private keys or seed phrase.
Not using it to go online but online while making transactions
Still install anti malware against malware

So, he use the phone only as wallet and for crypto transactions. So, what do you think. Is this a good idea?

[nc50lc]

2 Mobile phones? Then it's better to use the other one as a cold-storage for signing transactions,
and use the main online phone as the paired watch-only wallet for monitoring the balance and creating transactions.
It's a lot safer than just using one of the phones as a wallet.

[Charles-Tim]

2 Mobile phones? Then it's better to use the other one as a cold-storage for signing transactions,
and use the main online phone as the paired watch-only wallet for monitoring the balance and creating transactions.
It's a lot safer than just using one of the phones as a wallet.

I am still new and this sounds new to me. How can this be done?
Please, do you have any article for this?

[NeuroticFish]

Not using it to go online but online while making transactions

This is still unsafe. As long as it goes online even for a minute, hacks can happen.

To be more clear, did you mean to use it as a multisig wallet?

He said it right, he meant cold storage.
One phone stays offline ever and it's used only to sign transactions. The normal phone has watch only wallet, can make transactions, can broadcast transactions, can see the status of the funds, but it needs the "cold" phone for signing. Of course, the information transfer will not happen through internet, since the "cold" phone will always stay offline.

Edit: things to read (they are for computer/laptop, but you will get an idea)
https://bitcointalk.org/index.php?topic=3171247.0
https://electrum.readthedocs.io/en/latest/coldstorage.html

[nc50lc]

To be more clear, did you mean to use it as a multisig wallet?

Uh, nope.
What I described is a cold-storage set-up which is a lot secure than directly using a mobile as a wallet.

You can use two Electrum mobile to do that and phones with working camera (Only download Electrum from: https://electrum.org/#download).
One offline phone containing the seed and another one with just the master public key that can't be hacked.

Please, do you have any article for this?

I'll edit this post / reply with the steps since I haven't found a tutorial for electrum mobile in the internet.

[Twinkledoe]

In my opinion, that's fine with me as long as you are not storing your other coins. If you will just use it for payment transactions and not really storage of your important ones, just for convenient purposes of your short term transactions. Because at some point, you might lose it for no reason. Just think of the worst possible scenario so you know what contingencies you will do if it really does happen.

[nc50lc]

Okay, here's the procedure to create a cold-storage mobile Electrum wallet:

• 1. Install Electrum on both devices, and create a standard wallet on the "cold storage" device, that will be your main wallet that contains all the keys and shouldn't be connected to the internet even once (a newly formatted device/new device is better).
  Make sure that the seed was saved in a physical backup like a piece of paper.
• 2. Click the wallet's name on top of the screen and click "Master Public key" twice to open the QR code.
• 3. On the online phone, create a new wallet using the option "Standard Wallet->Use a master key", then click the camera icon to scan the cold-storage wallet's QR code.
  This will create a watch-only wallet version of your cold-storage wallet.
• 4. Confirm if the address in the receive tab is the same.

Now to use those wallets:

• You just have to create a transaction using the online watch-only wallet using the send tab.
• Fill out the recipient, amount, etc. then, click pay (select if you want to opt-in RBF, yes) and click the QR code icon below.
• In the cold-storage wallet, go to send tab and click the camera icon on the right side and scan the other device's QR code.
• The transaction will be imported to the cold-storage wallet, now click option->sign (enter your pin) and it will be marked as "signed" above.
• Click the QR code icon, then scan this using your online watch-only wallet and the signed transaction will be imported and now you can use options->broadcast button to send it to the network.

If you're not familiar with Electrum's defaut bitcoin denomination, you can change it from mBTC to BTC in the settings->denomination.

[CucakRowo]

Using mobile phone (one of two) as a full mobile wallet. Why not?
As long :
- The phone has no social media installed or any other programs (like games, etc). Phone is dedicated solely for crypto.
- The phone active and online only for transactions.
- There are no seeds, private key stored in the phone (please avoid this). Save it in other place.

[Charles-Tim]

This is so informative, thanks so much. So far you talk about the phone camera, it means I can make use of QR code to easy complete the transactions by using the cold mobile device for signing. It is a lot better than using USB stick.

[hatshepsut93]

This setup might be viable if you can't afford a real hardware wallet and you have a spare phone that can be turned into a cold storage, but if you want to buy a new phone for that, you'd better just buy a hardware wallet instead. This setup is less secure than a hardware wallet, your phone might have some spyware installed by the vendor, especially if it's a cheap phone, and it can be trying to connect to networks even without your permission.

[RapTarX]

When a wallet gets connected with online, it's not safe anymore regardless of what step you take or whatever. I don't know if it's possible to create multisig wallet from mobile; that would be the best idea keep fund safe.

[mk4]

Theoretically you can do it. It's just going to be tough and it's going to take a good amount of research and effort to reach higher security. If you really really want a secure device, it's not going to be as easy as uninstalling all apps and leaving just one wallet app. If you really want security, you'd probably have to encrypt the phone's storage, and use a better mobile OS, probably like Graphene OS or an OS that doesn't have wifi and data drivers if you really want a cold storage.

But to be honest, spare all the headaches and just purchase a hardware wallet lol. Unless you enjoy having to tinker with devices, then feel free to go with that setup.

[Lucius]

Mobile wallet as "main or full storage" it's never a good idea, although in the absence of any other choice there are several things to keep in mind. The first in my opinion is definitely the choice of a smartphone, because if you want to have relatively secure hot wallet you need a secure device, and by that I mean the newest OS that will receive security patches on a regular basis. Then such a phone should be adequately protected (in the same way as a desktop computer) and only then can we install a proven mobile crypto wallet.

Of course, cold storage is a much safer choice, and if you have an older smartphone why not try to secure your funds in a completely free way.

[Sonu_titu]

This could be so hilarious but I just need you to contribute.

If someone has two mobile phones, deciding to use one as a mobile wallet. To me, this is a good idea as one of the phones can be useless. And having in mind to use it as wallet and putting these in consideration.

Having back up of his private keys or seed phrase.
Not using it to go online but online while making transactions
Still install anti malware against malware

So, he use the phone only as wallet and for crypto transactions. So, what do you think. Is this a good idea?

Instead of buying a extra phone you can buy a hardware wallet and store the seed by writing down on a paper. Hardware wallets are far more better than mobile wallet.

[taufik123]

Better advice than using 2 cellphones as a mobile wallet and making transactions.

Instead of buying a extra phone you can buy a hardware wallet and store the seed by writing down on a paper. Hardware wallets are far more better than mobile wallet.

Hardware wallet will certainly be safer compared to mobile wallet, because the hardware wallet has better security and can also be synchronized with your cellphone or computer, depending on the features provided by the hardware wallet used.

The use of a mobile wallet has many risks if you are not aware of its use, one of which is malware that will attack the security of your cellphone. To overcome this, periodic scanning should be done to ensure there are no viruses or malicious applications installed on your cell phone.

But still the use of hardware wallet is better and safer compared to using 2 cellphones as the method you use.

[madnessteat]

~snip~

Of course it's possible to use a smartphone for cold storage, but I don't see the point in reinventing the bike.

I fully support mk4 that you better buy a hardware wallet (Ladger, Trazor) or use Raspberry Pi 4 and Electrum for cold storage of bitcoin.

[Shimmiry]

This could be so hilarious but I just need you to contribute.

If someone has two mobile phones, deciding to use one as a mobile wallet. To me, this is a good idea as one of the phones can be useless. And having in mind to use it as wallet and putting these in consideration.

Having back up of his private keys or seed phrase.
Not using it to go online but online while making transactions
Still install anti malware against malware

So, he use the phone only as wallet and for crypto transactions. So, what do you think. Is this a good idea?

I think it's not a good idea. Why? Almost every smartphones are vulnerable to threats even you install many anti-virus and anti-malware in it. And having your money and private keys stored in just a single device makes it much riskier. If you would only use it for the private key and seed phrase storage, what if you lost it or you accidentally broke it? Better to have backups in a lot of platforms. And, why not use hardware wallets instead?

[libert19]

Kinda off topic but why not buy a hardware wallet and use it with your phone with otg cable? That will be much more secure imo. Will be more convenient than having 2 phones as well.

[boyptc]

Someone has shared the same idea before and it's also with the use of an extra laptop. But rather than using a phone as a cold storage better to use the hardware wallets that we use like ledger.

Sell the phone that you won't use anymore and use the money to purchase a hardware wallet.

[bakasabo]

Chances of your second phone with mobile wallet app being stolen, lost, broken, becomes suddenly a brick after a new firmware update is higher than simply holding funds on a ledger/trezor like hardware wallet.

Imagine your are keeping your phone at home and suddenly someone brakes in. First thing he will steal will be gadgets like phones, laptops - something that will be easy to sell in pawnshop. But who would take cheap usb flash drive, sorry crypto hardware wallet?

Plus this hardware wallets have built in security, and your mobile has? Pin code ? Home screen protection code ?