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Title: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogothmanhattan on December 26, 2020, 06:38:43 PM One of my most favorite ways of storing bitcoin is on a paper wallet. Paper wallets if done right are one of the most secure ways of storing bitcoin especially if done on an air gapped computer which in my opinion is a must.
The tricky part is when the time comes to sweep the wallet and that is where screwups can happen. If your computer or phone has a malware or virus infecting it, then chances are you can lose your bitcoin. One way to prevent this from happening is to never expose your private key to a hot wallet or the internet, but rather have it signed using an airgapped device with a wallet on it. We will be using Electrum and to make sure you have the right Electrum, you can read about it on this thread I wrote on another way of siging a BTC transaction where people brought up ways to make sure your electrum download is not tainted in anyway. https://bitcointalk.org/index.php?topic=5106013.0 www.electrum.org I will use cell air gapped cold wallet to cell hot wallet So in this setup we will have a cellphone and a computer both installed with the latest version of Electrum. These are the steps I took.... Wipe out all data on cellphone and have it reboot with factory reset, thus cleaning it of any malware or viruses. Install Electrum and then place it in Airplane mode, disable wifi, disable bluetooth, remove sim card and also remove the antenna thus making it air gapped. Creating new wallet as follows..... https://talkimg.com/images/2023/06/12/AiUlC.jpeg Click NEXT then name your wallet https://talkimg.com/images/2023/06/12/AiXmb.jpeg Next create new password https://talkimg.com/images/2023/06/12/AidVv.jpeg The select type of wallet you are creating..in our case we are importing a public or private key. So up to this point you can use for both the air gapped and live hot phone electrums. Click on the camera tab to scan the qr code. https://talkimg.com/images/2023/06/12/AiuDH.jpeg Here I will be importing the private key for the air gapped wallet phone https://talkimg.com/images/2023/06/12/AiAZg.jpeg You can do the same for the HOT LIVE Cell phone wallet, BUT, ONLY IMPORT THE PUBLIC KEY! On the air gapped phone the OFFLINE will show as there is no connection with any internet signal. Thats exaclty what we want to see. https://talkimg.com/images/2023/06/12/AiHkI.jpeg When clicking receive on both phones, and then request, the public address matching THAT particular private key will show. The Air gapped and the Hot phone Public addresses should both match! https://talkimg.com/images/2023/06/12/AiSgd.jpeg https://talkimg.com/images/2023/06/12/Aind5.jpeg On the HOW LIVE phone, click click scan and scan qr code of public address you want to send the paper wallet funds to Then Click amount and send MAX. Always sweep a paper wallet fully! https://talkimg.com/images/2023/06/12/AiCFz.jpeg https://talkimg.com/images/2023/06/12/AiQo2.jpeg You can set the mining fees on the app, Change the method to "Static", you will be able to set the transaction fee to lower amounts. Look at the image below. The fee is only 1 sat/byte. https://talkimg.com/images/2023/06/12/AiGlc.png Next click PAY and the following information will show. Here you can check amount of BTC sent, mining fee and most importantly BTC address where bitcoin is being sent to. https://talkimg.com/images/2023/06/12/Aim6P.jpeg Next click on QR tab and the following RAW UNISGNED TRANSACTION QR code comes up. https://talkimg.com/images/2023/06/12/Ai6Vq.jpeg Now with your air gapped phone click on SCAN and scan the QR code from your live phone. This will take your raw unsigned transaction into your cold air gapped phone with the private key to be able to be signed! This is what will show on your air gapped phone after scanning the QR code from the LIVE HOT phone wallet. https://talkimg.com/images/2023/06/12/AiPDj.jpeg Next click on the sign TAB and the following will come up confirming you want to sign the unsigned transaction. https://talkimg.com/images/2023/06/12/AiTnG.jpeg Once you click on yes, the new window coming up will show you a signed BTC transaction with the address the btc is going to also the amount! This way you can be sure the btc is going to the BTC address you want it to goto and not some malware altered BTC address!! Also the TX data is also present and showing. https://talkimg.com/images/2023/06/12/AitkD.jpeg Now for the final steps of transferring this to your hot phone by clicking on the QR tab on the air gapped phone which will produce a QR code. Take your live HOT Wallet phone and click on Scan, then scan the QR code from the Air gapped wallet. The following will show up, and again you can confirm and the information. Once you are satisfied, click on Broadcast and the raw transaction will be broadcast on blockchain and the bitcoin will be transferred from your paper wallet to the BTC addy of your choice. https://talkimg.com/images/2023/06/12/Aizgf.jpeg I hope this helps people understanding how a paper wallet can be swept without ever having to expose the private keys to a HOT wallet. Again test with a very small amount of BTC until you have it nailed down and feel comfortable in doing this. Made another visual aid to make it even easier to understand. https://talkimg.com/images/2023/06/12/AiNuZ.png or full version here https://talkimg.com/images/2023/06/12/AiEF8.png https://talkimg.com/images/2023/06/12/AiIo3.png https://talkimg.com/images/2023/06/12/Airu1.png https://talkimg.com/images/2023/06/12/Ai1Nm.png https://talkimg.com/images/2023/06/12/AiLoW.png https://talkimg.com/images/2023/06/12/AicxJ.png https://talkimg.com/images/2023/06/12/AioPC.png Title: Re: Ofline siging your paper wallet using air gapped phone via Electrum Post by: krogothmanhattan on December 26, 2020, 06:39:01 PM THIS OFFLINE WALLET SWEEP WILL BE USING AN AIR GAPPED PHONE AND A PC ELECTRUM.
Again create the same steps you did with the air gapped wallet as we did in the example above. Next for the hot wallet on the PC, install Electrum.... https://talkimg.com/images/2023/06/12/Ai9CH.png STEP 1 NAME YOUR WALLET STEP 2 CREATE NEW WALLET...SELECT IMPORT BITCOIN ADDRESS On the hot live PC wallet, we will be importing the public address ONLY STEP 3 Click on camera tab and scan in front of pc camera the Public address part of your paper wallet. HIDE THE PRIVATE WALLET, MAKE SURE NOT TO EXPOSE IT TO CAMERA!! As you notice, if bitcoin word is in front of the address then you need to delete the word otherwise the next button will be greyed out. STEP 4 Once the public address is on their click on next, a password option is given, if you want to add you can otherwise hit next. https://talkimg.com/images/2023/06/12/AiBvg.png STEP 5 Watch only wallet created meaning the paper wallet public address is on the electrum with no private key which is EXACTLY WHAT YOU WANT! Click OK and the click on the send tab STEP 6 Click on camera tab on the pay to box, this will activate your computer camera. SCAN the QR code for the public address you want to send all the funds from your paper wallet to. Then click on MAX on the amount line. You should see the full amount of the balance minus miner fees in this box. Then click PAY STEP 7 You can see you have an unsigned transaction in the highlighted box top left. Also I adjusted the miners fee down to 2 sats in the middle highlighted box. In the outputs boxe, you can find the public address where the funds will be sent to. SO double check to confirm it is correct, with the amount to be sent as well. Click FINALIZE STEP 8 You now have an UNSIGNED transaction ready to be signed on your air gapped phone. Click on export and then show as QR code. Once the QR raw transaction pops up, scan with you are gapped wallet and the following will come on the screen... https://talkimg.com/images/2023/06/12/AigiI.png STEP 9 The unsigned transaction scanned into your air gapped phone will be shown. Click SIGN STEP 10 Confirm signing transaction...Click OK STEP 11 You can now see on top it says signed and also the transaction ID is shown as well. This is ready to be broadcast as the button is available as well, but since this is an air gapped phone you cannot, so we need to click on the QR code and take back to the live wallet on the PC. Also you can double check amount and pub address where the funds are to be sent to to confirm nothing has changed!! https://talkimg.com/images/2023/06/12/AiKN5.png STEP 12 On laptop Electrum, On top where the tools tab is click on load transaction and then select QR code. This will activate camera, the scan the QR code raw transaction from your air gapped phone. STEP 13 You will see the identical information you have in your air gapped phone come up. Again double check to confirm all is correct! Once ready, click broadcast and your raw transaction has been sent to the blockchain! The payment sent TX id will pop up as well! Hope this helped you all, any questions ask!! To recap... https://talkimg.com/images/2023/06/12/Aib4z.png Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: iBitcoinHongKong8 on December 26, 2020, 07:13:27 PM Fantastic thread Krogoth! Absolutely amazing to get this amount of detailed step by step instructions all while remaining as secure and safe as possible. I'd have given more merit but all I had was 1 to send. If I had 50 I would have happily sent you 50! I'm still getting used to Windows and Android so it will take me a while to learn and play around with super small amounts to get comfortable but I want to learn all ways of doing it. I understand how to use Electrum with a MacBook and that's been good, but I want to learn as much as possible and it's threads like these that gift our community with such valuable information and help! Cheers all and thanks again Krogoth. You the man!
iBHK8 Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: Kakmakr on December 26, 2020, 07:30:34 PM Is there any way for someone to hijack the transaction when you go online to sweep the wallet? I have been asking for a method where you do this whole process "Offline" and that the "Private Key" get encrypted, before you go "online" again to finalize the process.
So you would be doing this offline and it only finalizes the process on the Blockchain the moment when you go "online" again. (Difference being that the "Private Key" would be encrypted already, before you go online. (If the packet gets hijacked, the hacker will have an encrypted version of your "Private Key and the "Private Key" will not be in it's raw format on the Internet.) ;) Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: hosseinimr93 on December 26, 2020, 07:33:23 PM You can set the mining fees on the app, but IMO they are still too high. With the PC version I can adjust down to 5 Sats but I cannot see that available on the app. If you change the method to "Static", you will be able to set the transaction fee to lower amounts. Look at the image below. The fee is only 1 sat/byte. https://i.imgur.com/2yPTcrG.jpg Is there any way for someone to hijack the transaction when you go online to sweep the wallet? I have been asking for a method where you do this whole process "Offline" and that the "Private Key" get encrypted, before you go "online" again to finalize the process. The raw transaction doesn't include your private key. You may ask how nodes validate the transaction without the private key. When you sign a transaction, you generate a hash and a signature using your private key. For validating the transaction, nodes calculate the hash using your public key and your signature without any need to your private key. If the hash calculated by nodes matches the hash already generated by you, your transaction is validated. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 26, 2020, 07:57:34 PM You can set the mining fees on the app, but IMO they are still too high. With the PC version I can adjust down to 5 Sats but I cannot see that available on the app. If you change the method to "Static", you will able to set the transaction fee to lower amounts. Look at the image below. The fee is only 1 sat/byte. https://i.imgur.com/2yPTcrG.jpg Awesome to know! Thankyou...it was driving me crazy paying those fees! Will add a new pic once i go back on my main computer...cheers! Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: Sanglotslongs2 on December 26, 2020, 09:01:15 PM Nice setup ! As phones are cheaper and cheaper, they are a lot of useless phone, this give them a second life !
But be carefull with the antenna, must be removed to be sure. Also, QR code transfert are really good, because there is few information, so you will be 100% sure it's legit way to communicate between devices. If you use USB on a computer there is a lot more "memory" available so a virus can possibily steal your coins... QR code ftw :) Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: NotATether on December 26, 2020, 10:28:43 PM (I tried this but my PC electrum s]crashed everytime I attempted to place the signed transaction back into the PC, so I had no choice but to use 2 Cell phones, one air gapped and the other hot.) The PC electrum allows much better control of mining fees compared to the cell app. I'm curious to know if Electrum ever displayed a stack trace or at least an error message before exiting. I'm tempted to run it in a Python debugger to see exactly what's going on if it doesn't involve connecting a hardware wallet. I don't have any handy. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 26, 2020, 10:29:15 PM Nice setup ! As phones are cheaper and cheaper, they are a lot of useless phone, this give them a second life ! But be carefull with the antenna, must be removed to be sure. Also, QR code transfert are really good, because there is few information, so you will be 100% sure it's legit way to communicate between devices. If you use USB on a computer there is a lot more "memory" available so a virus can possibily steal your coins... QR code ftw :) Yes...not all antennas are easily removed. The first cheap phone lg i bought..even the phone professional didnt want to try. Then i found this model. https://youtu.be/ICV7vPF9mPE As soon as you remove the battery...the antenna is there...5 screws and its out! Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 26, 2020, 10:30:10 PM (I tried this but my PC electrum s]crashed everytime I attempted to place the signed transaction back into the PC, so I had no choice but to use 2 Cell phones, one air gapped and the other hot.) The PC electrum allows much better control of mining fees compared to the cell app. I'm curious to know if Electrum ever displayed a stack trace or at least an error message before exiting. I'm tempted to run it in a Python debugger to see exactly what's going on if it doesn't involve connecting a hardware wallet. I don't have any handy. An error window did pop up...i will get a pic tomorrow for you. Edit...btw...i installed it using a windows installer and also just downloading it and start via exe file directly. Via windows installer startup the electrum vanishes. Via the exe file directly...the windows error pops up. I did in two different computers! Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: PrimeNumber7 on December 26, 2020, 11:42:12 PM Wipe out all data on cellphone and have it reboot with factory reset, thus cleaning it of any malware of viruses. Install Electrum and then will place it in Airplane mode, disable wifi, disable bluetooth, remove sim card and also remove the antenna thus making it air gapped. How are you getting electrum onto your phone? Are you downloading it? Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 26, 2020, 11:47:51 PM Wipe out all data on cellphone and have it reboot with factory reset, thus cleaning it of any malware of viruses. Install Electrum and then will place it in Airplane mode, disable wifi, disable bluetooth, remove sim card and also remove the antenna thus making it air gapped. How are you getting electrum onto your phone? Are you downloading it? Yes downloading it before antenna is removed Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: NotATether on December 26, 2020, 11:48:59 PM An error window did pop up...i will get a pic tomorrow for you. Edit...btw...i installed it using a windows installer and also just downloading it and start via exe file directly. Via windows installer startup the electrum vanishes. Via the exe file directly...the windows error pops up. I did in two different computers! So this is an error coming from Windows Problem Reporting or something like that name. What's your Windows version? You don't see a console window appear even briefly? That indicates that Windows was able to run electrum but Electrum itself hit an exception. I'm not sure how much this will help but if you run Procmon[1] and filter it to capture events from the Electrum program and PM me the saved output, I might be able to see if it has something to do with your Windows installation. From experience I know that Electrum works on a clean windows install. [1]: https://docs.microsoft.com/en-us/sysinternals/downloads/procmon (https://docs.microsoft.com/en-us/sysinternals/downloads/procmon) Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 26, 2020, 11:52:46 PM An error window did pop up...i will get a pic tomorrow for you. Edit...btw...i installed it using a windows installer and also just downloading it and start via exe file directly. Via windows installer startup the electrum vanishes. Via the exe file directly...the windows error pops up. I did in two different computers! So this is an error coming from Windows Problem Reporting or something like that name. What's your Windows version? You don't see a console window appear even briefly? That indicates that Windows was able to run electrum but Electrum itself hit an exception. I'm not sure how much this will help but if you run Procmon[1] and filter it to capture events from the Electrum program and PM me the saved output, I might be able to see if it has something to do with your Windows installation. From experience I know that Electrum works on a clean windows install. [1]: https://docs.microsoft.com/en-us/sysinternals/downloads/procmon (https://docs.microsoft.com/en-us/sysinternals/downloads/procmon) Will give to all tomorrow...and one computer is brand new dell..so as clean as they come I hope. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: NotATether on December 26, 2020, 11:55:20 PM Will give to all tomorrow...and one computer is brand new dell..so as clean as they come I hope. Just make sure that Procmon is capturing events before you start Electrum, or it's going to miss some at the beginning. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: ranochigo on December 27, 2020, 02:39:57 AM You may ask how nodes validate the transaction without the private key. To be more specific, the signature is contained in the scriptsig, together with the public key. The validation is done then with the signature in the first ~70ish bytes and the public key at the end. There's no hash but the nodes will calculate the signature with your raw transaction and your private key. The signature encompasses the entire transaction and as with public key cryptography, you only need the public key to match the signature.When you sign a transaction, you generate a hash and a signature using your private key. For validating the transaction, nodes calculate the hash using your public key and your signature without any need to your private key. If the hash calculated by nodes matches the hash already generated by you, your transaction is validated. I don't think factory reset will necessarily cover all the malware there is, some malware can exploit the privilege escalation to plant itself into the firmware and factory reset won't remove it. It seems pretty hard for the malware to really transfer information anyways so it's not that big of a deal even with malware. I think using Tails on a USB would be quite convenient as well. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: coinableS on December 27, 2020, 04:58:29 AM Is there any way for someone to hijack the transaction when you go online to sweep the wallet? I have been asking for a method where you do this whole process "Offline" and that the "Private Key" get encrypted, before you go "online" again to finalize the process. You can build one with bitcoin libraries like nbitcoin or bitcoinjs (for example). Or use one already created by someone else like coinb.in by outkast or coldsigner(https://github.com/coinables/coldsigner) that I made. The ways these work is basically all you need to create an unsigned bitcoin transaction is (3) things:
This is the essential data of a UTXO, and this part is usually done online unless you saved this information ahead of time. You can now take this data (unsigned bitcoin transaction) offline, sign it with your WIF private key in a secure air-gapped environment, and then it is ready for broadcast. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogothmanhattan on December 27, 2020, 03:57:36 PM Will give to all tomorrow...and one computer is brand new dell..so as clean as they come I hope. Just make sure that Procmon is capturing events before you start Electrum, or it's going to miss some at the beginning. You would not believe what was causing the error. First I bought and installed procman, but before I used it , I tried electrum again, and I noticed instead of going to load transaction I click on sign verify message instead of load a transaction...I guess my brain was a bit fried at that point. Anyway, so today I continued and just briefly did a succesful transaction which I tried again to replicate and post in here step by ste with pics. Well guess what, at the end at exactly the part where I want to load a transaction with a QR code, to my horror this error came up. https://talkimg.com/images/2023/06/12/AiD22.png AHHHHHH!!! Then I have no idea why I thought about it, I realized my electrical tape was still covering my camera ( YES I cover my camera), I restarted electrum and this time it worked like a charm!!! :D You can see the step by step between Laptop and air gapped phone here https://bitcointalk.org/index.php?topic=5303860.msg55941154#msg55941154 Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: PrimeNumber7 on December 28, 2020, 03:53:02 AM Wipe out all data on cellphone and have it reboot with factory reset, thus cleaning it of any malware of viruses. Install Electrum and then will place it in Airplane mode, disable wifi, disable bluetooth, remove sim card and also remove the antenna thus making it air gapped. How are you getting electrum onto your phone? Are you downloading it? Yes downloading it before antenna is removed I am also not a fan of using paper wallets as a means of cold storage. If you were to generate a wallet on your cold storage phone, there is a subset of possible vulnerabilities in which your phone could leak your private keys. If you use a paper wallet to store your private keys, you will be subject to the same vulnerabilities as if you were storing the private keys on your phone, and in addition will be subject to additional vulnerabilities when you print your paper wallet, and when you move the private keys from your paper wallet to your cold storage phone. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: Evilish on December 28, 2020, 05:23:30 AM Great post, krogothmanhattan. Good to learn that you can do this with phones too.
I will also add that if you use Coldcard wallet (a hardware wallet), this process becomes a little simpler as the wallet has a built-in way to sign transactions offline. It goes like this: 1) You generate a transaction on Electrum desktop and export it to file as PSBT, copy that file to a MicroSD card 2) Insert the MicroSD card into Coldcard wallet and sign the PSBT 3) Coldcard wallet will generate the final transaction and save that to the MicroSD card 4) Insert the MicroSD card into your PC through a card reader, copy the final transaction, and finalize the transaction on Electrum Takes a couple minutes to finish the transaction, but it's really the most secure way I've found on signing transactions offline. Your private key never touches your computer or your phone which is great. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: BrewMaster on December 28, 2020, 02:04:15 PM 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. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 28, 2020, 02:15:07 PM 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. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogothmanhattan on December 28, 2020, 07:35:03 PM 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 (https://bitcointalk.org/index.php?topic=5296179.msg55742293#msg55742293) Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: PrimeNumber7 on December 29, 2020, 05:53:38 AM 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. 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. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on December 29, 2020, 01:26:16 PM https://i.imgur.com/UAVYLlt.png Made another visual aid to make it even easier to understand. or full version here https://i.imgur.com/uwmha5n.png https://i.imgur.com/Y51Gkb7.png https://i.imgur.com/xQvpXOv.png https://i.imgur.com/C6sBAaT.png https://i.imgur.com/qFKYXGM.png https://i.imgur.com/kIZ1Pgf.png https://i.imgur.com/LHGkebj.png Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: Dabs on December 30, 2020, 08:01:35 PM ... 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!) Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogothmanhattan on January 03, 2021, 07:07:50 PM 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. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: PrimeNumber7 on January 04, 2021, 05:34:37 AM ... 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!) 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. Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: krogoth on January 21, 2021, 12:09:06 PM 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.
Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: PacificKA on January 22, 2021, 10:28:54 PM 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.
Title: Re: Offline signing your paper wallet using air gapped phone via Electrum Post by: HCP on January 24, 2021, 12:28:33 AM 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? ??? |
