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Offline signing your paper wallet using air gapped phone via Electrum

Paper wallets if done right are one of the most secure ways of storing bitcoin especially if done on an air gapped computer.



The following content was written by krogothmanhattan on December 26, 2020, 06:38:43 PM in the thread Offline signing your paper wallet using air gapped phone via Electrum. It was archived as part of the Informative Bitcointalk Posts Initiative. All content is owned by the author of the post. (original)

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.

     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…..


       Click NEXT then name your wallet

      Next create new password

      The select type of wallet you are 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.


       Here I will be importing the private key for the air gapped wallet phone


       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.


        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!


           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!


         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.

         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

         Next click on QR tab and the following RAW UNISGNED TRANSACTION QR code comes up.


          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.


          Next click on the sign TAB and the following will come up confirming you want to sign the unsigned transaction.


           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


           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.


              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.

                   or full version here

The following content was written by krogothmanhattan on October 19, 2018, 04:57:14 AM in the thread Offline signing your paper wallet using air gapped phone via Electrum. It was archived as part of the Informative Bitcointalk Posts Initiative. All content is owned by the author of the post. (original)


   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….


                           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.


     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…


      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!!


      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…


Cover Image by Erdenebayar Bayansan from Pixabay

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What Everyone Must Know About GPU Crypto Mining

Yes, GPU crypto mining is still profitable. It just depends on which coins you mine.



Yes, GPU crypto mining is still profitable. It just depends on which coins you mine. Using the best GPU mining software, you can make a good return on your mining hardware for coins such as Ethereum. The manufacturer and model will clearly affect your choice of GPUs to use. Here are some answers to some of your burning questions about GPU crypto mining.

GPU mining is a process of solving complex maths problems for verifying electronic transactions using computer components. In this case, it utilizes a gaming computer’s graphics processing unit. It doesn’t have to be a gaming computer though and could even be a laptop.

Once a method of mining bitcoins, it has become obsolete several years ago for many different cryptocurrencies that use the Proof-of-Work algorithm. But some people still use it to mine bitcoins and other cryptocurrencies as well.

In the Proof-of-Work model, each miner searches for a hash that is less than a particular value which is called the nonce. The size of the nonce depends on the difficulty value of the cryptocurrency network. Higher difficulties make smaller nonces.

Will it be profitable?

Every miner asks themselves this question before they purchase large batches of mining gear. That is because GPU mining, like other types of mining, has marginal profits. In other words, you have to be very careful to generate more cryptocurrency than the amount you pay for electricity.

The profits of mining depend a lot on how fast you can find a block. So, if several miners shut down at the same time, the difficulty will be too high to mine blocks. Usually, networks periodically adjust the difficulty based on the number of recently mined blocks.

But it really depends on the quality of your GPU mining software whether you want to stick to GPU or some other powerful device like FPGA.

The reality of GPU crypto mining these days

Bitcoin mining these days have become very fast paced, and if you don’t have the latest bitcoin miners, then you are going to get left behind.

Application-specific integrated circuit (ASIC) miners took over the Bitcoin mining scene in 2013 causing many miners to switch their obsolete graphics card to script-based altcoins like Dogecoin and Litecoin.

Also in 2018, ASICs predominantly carried out crypto mining of several other coins. And hence mining these coins using GPU or CPU is very hard you are literally competing against large mining pools. Using GPU to mind them hence is pointless and highly unprofitable. Hence there has been a massive shift for miners towards ASIC.

We can say that a single ASIC miner has the equivalent computing power of several hundred GPUs. However, ASICs are non-programmable. That means that you cannot modify them to mine a different cryptocurrency than the one the manufacturer designed them to mine.

But yes, even though the GPU computing power is pretty low, you can still utilize them for mining cryptocurrencies like Ethereum, Zcash, etc. So we can use GPU mining here. But some altcoins weaken the speed of GPUs for crypto mining. For example, Monero uses an algorithm that you cannot optimize for GPUs and ASICs. That is why nobody makes ASICs to mine Monero.

Can you mine Bitcoin using GPUs?

The answer is NO! Don’t do that, because the major mining pools check for GPU and CPU miners and kick them off the pool to save server resources. Plus, the profits are very tiny and it will take you several years before you mine a good amount of bitcoin, whether using the latest NVIDIA card or something else. Most mining software discourages people to use their GPUs and CPUs for this reason.

We are aware of some altcoin mining pools which claim to pay out in BTC, but these are actually mining a different altcoin and converting it to BTC.

AMD vs NVIDIA crypto mining

One major advantage of using NVIDIA or AMD GPUs for crypto mining is that they are relatively cheap (compared to ASICs). Hence you can run multiple cards on the same motherboard while mining different cryptocurrencies simultaneously. Miners have long been using Nvidia cards that they have collected at bargains for crypto mining.

Miners are starting to think twice though, as Nvidia began cracking down on GPU crypto mining. They started because miners were buying all the graphics cards that were supposed to be for gamers. Recently, they have lowered the hash rate of the 3060 Ti GPU for Ethereum mining. At the same time, they made a special kind of GPU that you can only use to mine cryptocurrencies such as Ethereum.

We do not know yet if AMD will follow in their footsteps. For now, AMD cards are more suitable for new miners in terms of price as they are the price of almost 2/3rd of the NVIDIA cards. But NVIDIA cards are somewhat more powerful thanks to the CUDA runtime.

What is the best GPU mining software?

You can choose from Claymore, PhoenixMiner, or Cudo miner. Claymore has long been the king of crypto mining for NVIDIA and AMD cards, but it’s getting a bit old. It was last updated in 2019, and users have reported crashes when running it. Therefore, we do not recommend using Claymore miner anymore.

PhoenixMiner is a newer miner which users have reported success using, and can mine different kinds of algorithms. But users have reported fake copies of PhoenixMiner made by scammers, so stay vigilant. This is the real link to PhoenixMiner.

Cudo miner is software that can control the GPUs in your mining farm. It can mine several different coins and also uses an auto-switcher that always mines the most profitable coin at a given time.

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[GUIDE] How to create an online store and accept Bitcoin by using open-source

I’ve spent the past 15 days writing a very detailed tutorial on how to create an e-commerce store and accept Bitcoin, from scratch, with no coding skills required by using only free and open-source software.



The following content was written by Pavle on August 31, 2018, 02:43:53 PM in the thread [GUIDE] How to create an online store and accept Bitcoin by using open-source. All content is owned by the author of the post. (original)

I’ve spent the past 15 days writing a very detailed tutorial on how to create an e-commerce store and accept Bitcoin, from scratch, with no coding skills required by using only free and open-source software.

We’ve been running our own bitcoin store for a year now, and wanted to do something for the community and spread the adoption.

The article contains detailed instructions that will guide you through the process step by step.

It’s quite in-depth, there are 10200 words and I also recorded 18 videos to help you along the way.

You can read the article here

And watch the video in an assorted playlist here

Here’s the table of content

1. Under the Hood
1.1Web Hosting
1.1.1Shared Hosting
1.1.2Dedicated Hosting
1.1.3VPS Hosting
1.1.4Why do you need both VPS and Shared for this setup?
1.2Domain name and SSL
1.3.1WordPress Theme
1.3.2WordPress Plugins Server
1.4 The cost

2. Web Hosting
2.1Choosing The Hosting Plan
2.2 Domain name
2.3 Setting up the account
2.3.1 Extra Services
2.4 Phone verification
2.5 Creating WordPress and WooCommerce
2.6 E-mail verification (inbox)
2.7 Previewing the website

3.   Customizing WordPress
3.1 Logging into WordPress
3.2 Getting familiar with the back-end interface
3.3 Installing the Theme
3.4 Removing the demo content
3.4.1Removing the plugins
3.4.2Removing the Products
3.4.3Removing product categories
3.4.4Removing posts and comments

4. Woocommerce Customization
4.1WooCommerce General Settings
4.2 Creating WooCommerce Pages
4.3 Creating product categories
4.4 Adding products
4.4.1 Creating Simple Product
4.4.2 Creating Variation Product
4.5 Shipping rates and methods

5. Installing plugins
5.1 Adding Contact Form

6 Customizing Theme
6.1 Customizing Header
6.2 Customizing Footer
6.2.1 Adding About Us in the footer
6.2.2 Adding Bitcoin Accepted Here Sign
6.2.3 Adding Menus to Footer

7. Setting up BTCPay Server
7.1Installing BTCPay WooCommere Plugin
7.2 Connecting to a Third-Party Host
7.2.1 Registering with a third-party host
7.2.2 Pairing your store with a host
7.3 Installing BTCPay self-hosted Server
7.3.1 Buying the VPS
7.3.2 Creating an account
7.3.3 Creating the Virtual Machine Buying  additional volume Attaching a volume Enabling CPU usage
7.3.4  DNS Setup
7.3.5 Deploying BTCPay Server
7.4 Connecting BTCPay with your wallet
7.4.1 Connecting your wallet with Ledger Nano S
7.4.2 Connecting your BTCPay manually
7.5 Testing BTCPay Checkout

8.1Official documentation
8.2 Managing your orders
8.3 Free Plugins
8.4 Search Engine Optimization
8.5 Support groups
8.6 Marketing
8.7 Credits
8.8 The stores made by following this tutorial
8.9 Thank you

If you have any feedback, let me know.

If you or someone you know end up with making a store that accepts BTC by following it, please let me know, it would make my day 🙂

Let’s spread the adoption.
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[overview] Recover Bitcoin from any old storage format

The aim of this thread is to give a complete overview for anyone who finds Bitcoins in any storage format.



The following content was written by LoyceV on August 26, 2018, 01:09:32 PM in the thread [overview] Recover Bitcoin from any old storage format. All content is owned by the author of the post. (original)

[overview] Recover Bitcoin from any old storage format

I’ve seen many threads like: Recovering weird old wallet, and the answer is often very easy if someone recognizes the format.
Since the number of different formats will only grow, and (in the future) I expect more people to forget what format they used to store their Bitcoin 10 or more years ago, I’ve decided to create an overview.
The aim of this thread is to give a complete overview for anyone who finds Bitcoins in any storage format.

Work in progress
This thread is work in progress. Please post any missing storage formats or additional identifying data, so I can add it to the OP (and give you credit). I haven’t tried all possible wallets by myself, and I won’t claim to know all possible formats either. If you find a thread asking about a format not covered yet, please post a link.

Warning: take security precautions
First: make one or more backups (thanks DaveF)! Make sure you’re not working on the only copy you have, as you risk losing everything.
Make sure you know what you’re doing, before doing it! When in doubt, don’t do it.
Ignore or report unsolicited private messages from old or new users. Discuss your needs in public on Bitcointalk, but DO NOT post your private keys, seed phrase words, or wallet files. DO NOT trust “help” you receive by PM, you will get scammed. Be careful which screenshots you upload.
Don’t trust anybody with your private keys, unless you’re absolutely sure you would trust him with the same amount in cash.
Several websites try to have you download a compromised wallet. Ensure you’re using the official website before downloading, and check the installer’s signature/checksum (thanks ETFbitcoin).
Use an air gapped offline computer running from a Linux LIVE DVD (for example Ubuntu or Knoppix) without internet connection when necessary.
Don’t expost large amounts of Bitcoin to a hot wallet. Assume your system is compromised, and act accordingly. Don’t trust your Windows clipboard, malware can change your Bitcoin address to their own, and checking only the first few characters of the address is not enough to prevent this.
If you’re using a paper wallet, you should use the entire balance at once. If you use only a small amount, you risk losing the rest of your balance to a change address.

Where to send your Bitcoins
Before attempting to recover your funds, you should already know where to send them after recovery. Setting up a safe wallet is beyond the scope of this thread, I recommend to start your search here: Choose your [Bitcoin] Wallet. Consider whether or not you want to use a SegWit address.
Create one or more secure backups before funding any wallet.

Bitcoin private keys (this section is largely based on data from
  • WIF (Wallet Import Format) (51 characters base58, starting with “5”).
    Example: 5KMWmYkn5YWkJnUDG4utD9L1HXQv3DBseqqCGsQXmthcEerbA7k
  • WIF Compressed (52 characters base58, starting with “K” or “L”).
    Example: L41YPdADy46J9Vh77WGR2bktFwEZ6knza2Xim3Urq9CEWynkkLgn
    Note: both WIF and WIF Compressed are derived from the same private key, but result in different Bitcoin addresses.
  • Private Key Hexadecimal (64 characters [0-9A-F]) (less common).
    Example: CA9A061710B8BC582E1B8BB60D0F3F2751791888AB5C18737620087ABDF74A05
  • Private Key (44 characters base64) (less common).
    Example: ypoGFxC4vFguG4u2DQ8/J1F5GIirXBhzdiAIer33SgU=
  • Mini private key (30 characters base58, starting with “S”, see wiki)
    Example: Sf2i92UoH3kMooYXHdDQ4YQvLTdPrQ
  • BIP38 password encrypted private key (58 characters base58, starting with “6P”, see
    Example: 6PRNqE9p5hTUgNy5cxXnrfVKZPX5Qz8sqB7oNfDT9N3YdCM7rqRxruxkN1
  • Private key missing checksum
    Example: 5KMWmYkn5YWkJnUDG4utD9L1HXQv3DBseqqCGsQXmthcEerbA7k
    The last 7 characters of a private key are a checksum. backups used to omit the checksum. An easy way to restore it, is importing the private key without checksum into a new wallet at (nowadays, and then exporting it again. Note: I do not recommend exposing a private key to an online wallet, but if it was created by, it should be considered compromised anyway (source and details; this information may be inaccurate (thanks Coding Enthusiast)).
  • Private key for SegWit addresses
    A private key can be used to create SegWit addresses (starting with “3” or “bc1”). You can import them into Electrum by adding “p2wpkh-p2sh:” or “p2wpkh:” respectively in front of the private key (source and details).
  • Incomplete private key
    If a few characters of a private key are lost, there are still recovery options (missing 5 character on known locations, missing one character on unknown location (I haven’t tested this)), but further details would go beyond the scope of this thread.
  • Blockstack
    If you have Bitcoin in a CLI Blockstack node, read this topic and this topic.
If you have the private key, you can choose from many different wallets to import it. Electrum is probably the easiest. If the private key is in the wrong format, you can use (do this offline!!) to convert it to WIF or WIF Compressed.

Determine wallets based on filenames (note: these are the default filenames, you could have renamed yours)

Seed phrases, Word lists or Mnemonic phrases
Bitcoin wallets can be stored as seed phrases, usually 12 to 24 words long. The used words can be in several languages (thanks HeRetiK).
  • 12 words
    Example: thrive jump wheel calm eyebrow order ankle raven fee narrow diamond adult
    The seed can be extended with one or more custom words.
    Use Electrum, or iancoleman’s Mnemonic Code Converter (do this offline!!) to extract all private keys.
  • 24 words
    Hardware wallets, such as Trezor and Ledger, usually use 24 words.
    Example: party describe tunnel brother explain laugh hello have short wood bird desk liar pole neck push wine tooth young mean grain join cheap aisle
    Use the original hardware wallet, or iancoleman’s Mnemonic Code Converter (do this offline!!) to extract all private keys.
    A common mistake is using the words in the wrong order, where the words are written down like this:
    1 2
    3 4
    5 6
    7 8
    But you’re trying to recover them like this: 1 3 5 7 …… 2 4 6 8 ……
  • Another number of words
    If you don’t remember how the list was created, you can use iancoleman’s Mnemonic Code Converter (do this offline!!) to extract all private keys.
  • Missing or incorrect word(s)
    Try (I haven’t tested this) (do this offline!!) (thanks o_e_l_e_o)
  • Master private key (111 characters, starting with “xprv” (legacy addresses starting with “1”), “yprv” (backward-compatible SegWit addresses starting with “3”) or “zprv” (native SegWit addresses starting with “bc1”) (source).
    Example: xprv9xyQEZakyfuyCRGF1moJNatpGDAgMS4hgctAgWU4RNw664qCz6agreZParHx6G24td48SZKnmK8 ppSVMvmyBuTy9L4poDhwgm9aR9GukgQW (source & further reading)
    Use Electrum > create new wallet > enter seed.
  • Armory Root Key: 18 four letter “words”.
    Example (from eoaj gghu ruaf ghwe jnrh ftuu hweu aeun agkg tudt waja gunn oawg jkwh dhei hjdn itar naoj
    Use Armory.
  • To recover an old legacy wallet, read this topic and go here.

No wallet?
If you can’t find your wallet.dat, because it’s deleted or renamed, you can try these options (do this offline!!) after you’ve made a backup of the entire partition.

  • Pywallet can search for private keys on an entire partition, even when the wallet has been deleted.
  • Findwallet can search for a wallet file after it was renamed (but not deleted)

After recovery
If your address was funded early enough, you also own Forkcoins. Read the link, it may be well worth your time.
For future backups, make sure to keep all information needed to recover your funds.

No spam
All my threads are now self-moderated to stop signature spam. I will remove all irrelevant posts. If you quote the entire OP, your entry will be deleted.
Once in a while I’ll summarize posts and clean up this thread.

This thread and board are meant for Bitcoin only. But, if something comes up, I’ll keep track of methods to restore a damaged private key for altcoins too. For future reference:

Use this information at your own risk. At all times, think before each action, especially when you’re dealing with private keys. When in doubt, don’t do it!
I’m human, I make mistakes. If something is incorrect, please let me know.

1MyMoney4uNt5afXALAZpoovJpqojEMkLP (Balance:
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