Topic: As a Bitcoin Core only user, how im supposed to pay someone in person? - page 2. (Read 600 times)

Then you have to change your mind. I use Electrum in my smartphone for years, have stored up to 1 bitcoin and never ever got it stolen. I don't suggest you to use your smartphone as a cold wallet but it can be a good hot wallet for hundreds of dollars or some thousands for a quick pay.

Oh, so you changed your mind and don't stick with Linux distro.
If I were you, I would buy The Passport Foundation wallet and would watch this tutorial - https://www.youtube.com/watch?v=Ri1ZBZZdQb0
By using The Passport wallet and your smartphone, you will feel secure.

Laptop may attract attention, someone accidentally may hit you with shoulder and you may drop your laptop, everything can happen, I wouldn't use laptop either. I think that chances of damagin laptop or getting it stolen is way higher compared to smartphone because everyone has smartphone today in the street and outside, just my two cents.

If not connecting to your node, then I would also use Orbot as ETFbitcoin has suggested.

Install the wallet app inside some kind of encrypted folder or partition on your phone. If a thief manages to steal your phone, even if they bypass your lock screen they won't even be able to see you have wallet app installed without breaking the encryption first.

I strongly dislike phones: they're annoyingly small to type, the screen is 5% of what I'm used to, they need daily recharging, and they're fragile. But: it's a necessary evil nowadays.

First: I've never lost my phone, but I always assume that can happen at any moment. That means I don't do banking on my phone, I use a separate email account, I backup my data, and for Bitcointalk I use my not-to-be-trusted Mobile account.
For small, "daily" transactions, I keep some crypto on Unstoppable wallet on my phone. I set it up to use "From Blockchain" instead of "API" for privacy, and to use Tor. That makes it slower, but more private. If I lose my phone, I'll sweep my wallet. The wallet has a PIN, the phone has it's own security. And the amount on there is low.

Yeah, those will work, but here's the thing: We are moving into a world where everyone has a mobile phone. The same cannot be said about computers. Therefore, it in the future when Bitcoin becomes more adopted, it is more likely that you will encounter a bitcoin-dealing merchant who utilizes a smartphone than someone who has a computer with them, and the technology has to be ready by then to accommodate both usages.

And one of them is already supported: Typing in the address and amount and click Pay/Broadcast/whatever. But we are not there yet in terms of QR Code and/or NFC methods of payment.

I mean in theory, there should already be a strong support for QR codes in particular, on mobile wallets, but for whatever reason, nobody can agree on a number one wallet app to use, which would make this process significantly easier for average bitcoin users to give instructions about to customers (because it is easier to remember how 1 wallet works than 10). Unstoppable Wallet for example looks very good for this sort of thing and has a good reputation, but most people are using crappy exchanges or closed-source wallets instead.

That's exactly why I'm not buying any of those phones. They're overcharging; probably their targeted audience is privacy concerned users who aren't competent with phones. If you dig it up a little bit, you can buy yourself a 300 EUR worth of Pixel, with Graphene installed, and it'll be both more secure and private than any of those.

• Or just a small laptop.
• You can use mobile data.
• I guess they can send you the address over some communication channel if QR is not a practical option. In the worst, type the address.

Average people don't use CLI. And i just remember most OS have option to increase display scaling, which usually problem about small screen with big resolution.


Install Orbot on your Android phone. The default setting use "full device VPN" mode which means all application use Tor network.

It is quite difficult to lug around everywhere (unless it's a macbook air or something else that's light), requires a WiFi access point, is inconvenient for scanning QR codes and is overall quite cumbersome to use for making payments when you're on the street.

That's why your other suggestion about getting a GrapheneOS phone is a much better idea.

For those that ask why I don't want a laptop, beside it just not being convenient to carry around, I don't want to look like an high level nerd. You see, the problem is, you never know who you are dealing with, a laptop is typically a place you would store more BTC than a mobile device, where one would expect to carry pocket change, so you want to minimize this risk. Let alone those Coldcard type devices. Those make stand out like someone that is invested into this way too much. If you are a regular fella with a fashionable android phone, it's a much better look than showing up with some fancy, strange device that looks like some sort of Bitcoin-only device.

Im going to look at the Fairphone thing. Im familiar with Purism, their prices are a scam, they get massive cuts for what it is. Im going to also need to know what OS to install in there. Someone mentioned Graphene but this is only for the Google Pixel for some reason, im not buying a Google phone. I have a dated Samsung Galaxy for a phone, does the trick. I don't even know what Android version this uses. Im not familiar with phones.

Btw, what I meant with this thread, wasn't to say, I want to use Bitcoin Core on a phone, I can reasonably compromise, I just want to do it properly. I will mix at home, get the amount to use ready, and put it into mobile Electrum or whatever. Im not going to know the address until I arrive, so I cannot sign it at home. Then I also need to sort out how to transfer this through Tor from the phone. What I don't like is the traces that this would leave in terms of, imagine you lose your phone somewhere or something. Since im not familiar with phones, I don't know what to expect if that happens. Could some experienced phone users comment on this whole process?

Over a dozen billion, called smartphones. 

No, seriously. Look. If you sell small amounts of bitcoin, then getting yourself a Pixel with GrapheneOS installed wouldn't be a bad idea. It comes a lot cheaper than Fairphone. The TL;DR of Graphene is that it focuses on security and privacy. That can work, and it doesn't make you look like a socially awkward fella with Arch Linux, having an NSFW anime-girl wallpaper. (No offense to those who do!  )

But seriously, why not a laptop? Having an Electrum wallet, running Ubuntu doesn't tell me anything. We are not living in the 00s anymore.

CLI


If it's not for regular use for a few minutes of dealing with a very difficult screen setup is probably not the worst.
And if you know where you are sending the BTC and the amount you can pre-populate it at home and just hit send once you get a wi-fi signal wherever you are doing the exchange.

-Dave

It has a 6" screen and weighs 1.03 pounds. This is designed for specific industrial applications. For me, 10" is the minimum to be able to type "normally". That brings me into the netbook category, but most of them lack RAM capacity.

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How about a good old paper wallet? Bitaddress.org is the easiest, but doesn't support Segwit. You can encrypt it with BIP38, and fund it with approximately the amount of Bitcoin you're going to need. When completing the trade, your trade partner can just sweep your private key from his own mobile device.

There are a lot of devices like this out there:

https://www.amazon.com/Industry-Portable-Computer-Notebook-Graphics/dp/B07QYZHM8F

I know running core on that would not work it's just the 1st one I found with a quick search.

Small enough to fit in a jacket pocket and you just look like a nerd / geek with an oddball computer.

There are a ton of other 'pocket computers' out there. Just how much do you want to spend.

If you are worried about your phone now being secure but you only do a couple of $200 transactions a year the payback time is long.
If you are doing a couple of $1000 transactions a week it's a different story.

-Dave

Yes, that's really crazy, especially when you look at the specs of the phone.
To compare this with the Fairphone 5 just from a memory perspective: The Fairphone has twice as much RAM (8GB vs 4GB) and also twice the memory (256GB vs 128GB).

They probably justify the price with their advertising where they proudly claim that a smartphone is "built outside China".

Install a privacy filter on your screen. Or does that make you stand out too?

There are many online tools that can be used for that. All you need to do is copy the raw (signed) transaction to your mobile and broadcast it using any of the avaliable tools.
In this way, you don't need to have your private keys in your mobile phone and that's what OP is trying to achieve.

Yes, of course. I know what you're getting at.
But the OP will have to use something to be able to transfer his transaction, won't he? Of course there are other wallets that support RBF, but he explicitly said that he only trusts Bitcoin Core on Linux.



This is correct if you did not allow the RBF feature when signing the transaction. Just as it is set by default.
However, if it is activated and the transaction is signed, there is a possibility that the transaction can later be replaced with a newer version with a higher fee.

At least that was my understanding, but I haven't had any practical experience with it yet. Please correct me if I misunderstood the feature and how it works irl.

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EDIT: Ok, I must have had a long brain lag.  Of course you're right @hosseinimr93. Because it acts like a new transaction with a different hash, it must be re-signed.

When you increase the fee, the transaction data changes, the signature becomes invalid and it's like that you are making a new transaction. If OP wants to sign the transaction again, he/she would have to get back home as he wouldn't have access to his/her laptop out of the home.

That doesn't help you if you brought a signed transaction to a meeting, and left your Bitcoin Core at home.

Sorry to step in but I would like to address your problems:

This could be fixed by using the RBF-feature(Replace-by-fee) in Bitcoin Core.
The requirement for this is that you activate the option when signing the transaction. By default, RBF is not activated. This is no longer possible afterwards!
The Full-RBF feature should be implemented by version 24.0

Yeah.. not the best condition to sign the transaction offline. I think in this case you have to use a mobile wallet.

In that case, I would still suggest that he perhaps encrypt the emails using PGP so that the seller feels more secure.
Another alternative would be other encrypted messengers.

Even if that wasn't an option for him, as in question/problem 2, I see no other option than to carry out the transaction face-to-face while using a mobile wallet.
However, as a buyer I would be suspicious in that case aswell as PGP encryption has proven itself over the years. So it makes no sense to me to reject the suggestion.

Why not?

I can think of many potential problems. What if:

• Transaction fees went up between creating the transaction and meeting in person?
• You buy something at a shop and their automated payment system won't be able to give you an address and exact amount before making the payment?
• The seller doesn't want to email you a Bitcoin address for various reasons?

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@OP: I use different wallets for different purposes. The purpose of mobile wallets is convenience for small amounts. You simply can't have it all with Bitcoin Core.
I often bring a laptop, not for making Bitcoin transactions but for other purposes. Nobody bats an eye if you pull out a laptop somewhere. Tether a hotspot on your phone and you have your own internet connection with you.