Offline signing your paper wallet using air gapped phone via Electrum

[BrewMaster]

and in addition will be subject to additional vulnerabilities when you print your paper wallet,

i just want to point out that if you create an HD paper wallet where you write down the mnemonic words on paper then there is no need for printing anything so you avoid the vulnerability that involves printers.

[1715080542]

1715080542

[krogoth]

and in addition will be subject to additional vulnerabilities when you print your paper wallet,

i just want to point out that if you create an HD paper wallet where you write down the mnemonic words on paper then there is no need for printing anything so you avoid the vulnerability that involves printers.

Yep...I practiced that idea..love it. But as far as printing goes...buy a non wifi printer...and only use printer with air gapped computer..PERIOD.  Thats what i do.  IF done using..then destroy printer if security is an issue. That will eliminate that vulnerabilty.

[krogothmanhattan]

Again for anyone who still loves the idea of paper wallets, I am conducting a test on these water proof papers.

Its been almost a month now for some submersed under water, and they have passed with flying colors!

I do recommend to use any of them or similar material if you make any. The worries of water will be eliminated some or completely!

https://bitcointalk.org/index.php?topic=5296179.msg55742293#msg55742293

[PrimeNumber7]

and in addition will be subject to additional vulnerabilities when you print your paper wallet,

i just want to point out that if you create an HD paper wallet where you write down the mnemonic words on paper then there is no need for printing anything so you avoid the vulnerability that involves printers.

This is true, however, it will not solve the problem I described. If you write down the seed, someone could view the seed while you are writing it down, or while you are importing the seed into an air-gapped computer/phone, or while you are transporting the paper wallet from your secure location to the location of your computer.

The chances of the above happening may be low, however, they are non-zero, and are in addition to the scope of vulnerabilities of having a wallet stored on an air-gapped computer/phone.

[krogoth]

Made another visual aid to make it even easier to understand.

                   or full version here

[Dabs]

... If you write down the seed, someone could view the seed while you are writing it down, or while you are importing the seed into an air-gapped computer/phone, or while you are transporting the paper wallet from your secure location to the location of your computer.

The chances of the above happening may be low, however, they are non-zero, and are in addition to the scope of vulnerabilities of having a wallet stored on an air-gapped computer/phone.

I think we all understand what you are saying, but this boils down to physical security already. If you do everything in a separate room, or one you properly prepared (or you can do what Snowden does and hides under a dark blanket), fire up some white noise or turn up the TV volume to mask ...

"So, there is a chance?" = that depends on how you do it.

For most people, they should not worry about it too much. For people like me who hold other people's coins in escrow, I've grown a habit of doing most of the things I mentioned above and then some; it doesn't hurt that I have other forms of physical security as well, armed guards at the gates, etc. If some government were to specifically target you, then you are screwed no matter what.

Everyone else, 0.000001% or 1 in ^256 = for all intents and purposes is impossible. (Peppa Pig says whistling is impossible! Just put your lips together and blow? It's impossible!)

[krogothmanhattan]

One other site I found that was helpful in trasmitting the raw TX was https://bitaccelerate.com/pushtx/

  PushTX - Broadcast Raw Bitcoin Transaction
With this tool, you can anonymously broadcast your transaction over the Bitcoin network. To do this, enter the raw transaction HEX in the form above and press the button. The service will send the transaction to our Bitcoin node, which is connected to over 100 other Bitcoin nodes at any time.

This way, your transaction will spread as fast as possible across all Bitcoin nodes. This will keep your anonymity because the transaction goes out of our node. We do not keep any information about the transactions we broadcast, nor about the users of this page. You can rest assured.

This service is using the "sendrawtransaction" method of the Bitcoin Core client. Your transaction must be signed and must not contain unconfirmed inputs.

   So when you have the signed transaction back on the live electrum, instead of broadcasting thru electrum, I copied and pasted it on the site.

[PrimeNumber7]

... If you write down the seed, someone could view the seed while you are writing it down, or while you are importing the seed into an air-gapped computer/phone, or while you are transporting the paper wallet from your secure location to the location of your computer.

The chances of the above happening may be low, however, they are non-zero, and are in addition to the scope of vulnerabilities of having a wallet stored on an air-gapped computer/phone.

I think we all understand what you are saying, but this boils down to physical security already. If you do everything in a separate room, or one you properly prepared (or you can do what Snowden does and hides under a dark blanket), fire up some white noise or turn up the TV volume to mask ...

"So, there is a chance?" = that depends on how you do it.

For most people, they should not worry about it too much. For people like me who hold other people's coins in escrow, I've grown a habit of doing most of the things I mentioned above and then some; it doesn't hurt that I have other forms of physical security as well, armed guards at the gates, etc. If some government were to specifically target you, then you are screwed no matter what.

Everyone else, 0.000001% or 1 in ^256 = for all intents and purposes is impossible. (Peppa Pig says whistling is impossible! Just put your lips together and blow? It's impossible!)

There is an additional chance, and there are additional precautions (costs) you can take to reduce these additional chances, but they are nonzero.

Or you could eliminate these additional chances by not using a paper wallet. While I do use paper wallets as a backup to my private keys, by default I will not use a paper wallet for accessing cold storage.

[krogoth]

I was asked by a member, he was trying to place the private keys of a loaded physical bitcoin like Casascius onto the electrum air gapped phone, but somehow electrum was not allowing him to type in the private keys manually. One way around this that worked out for me was to type in the private key on the phones mail...text..word wrap  or anything that can be typed into..then copy and paste it on electrum.

[PacificKA]

Wonderful explanation. Thank you. I use the desktop version and as such before I broadcast the final signed transaction, I verify it to ensure the transaction will do exactly what I want it to do. There are several offline tools you can use to verify a Bitcoin coin transaction. They give you a human readable output of the transaction to ensure the amounts and addresses involved are correct before you broadcast it.

[HCP]

I was asked by a member, he was trying to place the private keys of a loaded physical bitcoin like Casascius onto the electrum air gapped phone, but somehow electrum was not allowing him to type in the private keys manually. One way around this that worked out for me was to type in the private key on the phones mail...text..word wrap  or anything that can be typed into..then copy and paste it on electrum.

Correct... Electrum only seems to allow you to "paste" private key "text" in... you can't physically type it in... I've always found that a little bit "odd"... but possibly related to security issues around trusting 3rd-party keyboards?