I asked GROK3 how to set up a way to store amounts over 100k in Bitcoin so i could do a write up for ppl interested in learning how to do that. This was it's answer. I did specify to tell me about how to do it using Sparrow Wallet and Seed Signer project. Though it is a little complicated and advanced i think it is a VERY safe way to go about it.
Store large amounts of Bitcoin at home using Seed Signer.
Setting up a 2-of-3 multisig wallet with SeedSigner is a solid choice for securing your crypto, especially for a large amount like over 100k AUD. SeedSigner is a DIY, air-gapped Bitcoin signing device, meaning it’s offline and cheap to build (around $50 USD in parts), but it requires some hands-on steps. I’ll break it down simply and practically for a 2-of-3 setup—two signatures needed out of three keys. This assumes you’re starting fresh with SeedSigner and have basic tools like a Raspberry Pi Zero, camera module, and microSD card. Let’s go step-by-step.
What You’ll Need
Three SeedSigners: You can build three separate devices or use one and wipe it between uses (I’ll explain both options). Each represents one key.
Raspberry Pi Zero (no Wi-Fi), camera module, and screen (per device if building three).
MicroSD card (8GB+), card reader, and a computer.
Pen and paper or metal backup (like a steel plate) for seed phrases.
Sparrow Wallet (free software) on your computer for managing the multisig setup.
Note that you could also use Blue Wallet on your phone for this below instructions. I didn't specifically ask GROK this but you could, just make sure no seeds go on any online wallets only the xPubs which can be public and do not pose a security risk.
A USB drive or SD card for transferring files (air-gapped).
Option 1: Using One SeedSigner (Wipe Between Uses)
This is simpler and cheaper but requires careful seed management.
Build Your SeedSigner
Get a Raspberry Pi Zero, camera module, and display (check SeedSigner’s GitHub for exact parts).
Download the latest SeedSigner software (e.g., v0.7.0 as of now) from their official GitHub.
Flash it to your microSD card using a tool like Balena Etcher on your computer.
Assemble the Pi, plug in the camera and screen, and boot it up with the microSD.
Generate Three Seed Phrases
Boot SeedSigner, go to “Seed” > “Create Seed” > “24 Words” (for max security).
Write down the 24-word seed phrase it shows on paper or metal. Label it “Key 1.” Keep it secret and safe.
Go to “Seed” > “Export as SeedQR,” scan it with your phone or save the QR code image on a USB drive.
Shut down SeedSigner, remove the microSD, and reflash it with the software to wipe it clean.
Repeat this process two more times to create “Key 2” and “Key 3,” wiping the device each time. You now have three unique 24-word seeds.
Set Up Multisig in Sparrow Wallet
Install Sparrow Wallet on your computer (download from sparrowwallet.com).
Open Sparrow, click “File” > “New Wallet,” name it (e.g., “My2of3”), and select “Multi Signature” (2-of-3).
For each key:
Go to SeedSigner, load a seed (e.g., Key 1) via “Seed” > “Load Seed” > scan its SeedQR or type it in.
From SeedSigner’s main menu, select “Export Xpub” > “Sparrow” > show QR code.
In Sparrow, click “Add Device,” select “SeedSigner,” and scan the QR with your computer’s webcam.
Repeat for Key 2 and Key 3, wiping SeedSigner between each (or use saved QR images from the USB).
Sparrow will create a 2-of-3 multisig wallet with three public keys (xpubs). Save the wallet file.
Back Up Everything
In Sparrow, go to “Settings” > “Export” > “Output Descriptor” and save this file (it’s your wallet blueprint).
Store each seed phrase (Key 1, Key 2, Key 3) and the descriptor in separate, secure locations (e.g., safe, bank vault).
Test It
Send a tiny amount (e.g., 0.001 BTC) to the multisig address from Sparrow’s “Receive” tab.
To spend, create a transaction in Sparrow, export it as a QR, sign with SeedSigner loaded with Key 1, then wipe and sign with Key 2. Broadcast via Sparrow.
Option 2: Using Three SeedSigners
This avoids wiping but costs more (three devices).
Build Three SeedSigners
Assemble three separate SeedSigner devices as above, each with its own Pi, camera, screen, and microSD flashed with the software.
Generate One Seed Per Device
On SeedSigner 1, create a 24-word seed, write it down as “Key 1,” and export its SeedQR.
On SeedSigner 2, do the same for “Key 2.”
On SeedSigner 3, do the same for “Key 3.”
Keep each device powered off when not in use.
Set Up Multisig in Sparrow
Same as above: open Sparrow, create a 2-of-3 wallet, and add each device’s xpub by scanning their “Export Xpub” QRs one at a time.
Back Up
Save the Output Descriptor from Sparrow and store each seed phrase separately with its device number.
Test It
Send a small amount to the wallet, then sign a transaction with any two of the three SeedSigners.
Signing a Transaction (Both Options)
In Sparrow, go to “Send,” enter details, and click “Create Transaction.”
Export the unsigned transaction as a QR code.
Boot SeedSigner with Key 1, scan the QR, verify details, sign, and save the signed QR to USB.
Repeat with Key 2 on a wiped SeedSigner (Option 1) or second device (Option 2).
In Sparrow, import both signed QRs and broadcast the transaction.
Tips for 100k+ AUD
Diversify Storage: Keep Key 1 at home, Key 2 in a bank vault, and Key 3 with a trusted family member.
Add a Passphrase: On SeedSigner, you can add a custom passphrase to each seed for extra security (write it down separately).
Practice First: Test with small amounts until you’re comfortable.
Stay Air-Gapped: Never connect SeedSigner to the internet or type seeds into a computer.
This setup gives you a secure 2-of-3 multisig wallet. With one SeedSigner, it’s cost-effective but takes more steps. With three, it’s faster but pricier. Either way, you’ve got no single point of failure—perfect for big holdings.
I asked GROK3 how to set up a way to store amounts over 100k in Bitcoin so i could do a write up for ppl interested in learning how to do that. This was it's answer. I did specify to tell me about how to do it using Sparrow Wallet and Seed Signer project. Though it is a little complicated and advanced i think it is a VERY safe way to go about it.
Store large amounts of Bitcoin at home using Seed Signer.
Setting up a 2-of-3 multisig wallet with SeedSigner is a solid choice for securing your crypto, especially for a large amount like over 100k AUD. SeedSigner is a DIY, air-gapped Bitcoin signing device, meaning it’s offline and cheap to build (around $50 USD in parts), but it requires some hands-on steps. I’ll break it down simply and practically for a 2-of-3 setup—two signatures needed out of three keys. This assumes you’re starting fresh with SeedSigner and have basic tools like a Raspberry Pi Zero, camera module, and microSD card. Let’s go step-by-step.
What You’ll Need
Three SeedSigners: You can build three separate devices or use one and wipe it between uses (I’ll explain both options). Each represents one key.
Raspberry Pi Zero (no Wi-Fi), camera module, and screen (per device if building three).
MicroSD card (8GB+), card reader, and a computer.
Pen and paper or metal backup (like a steel plate) for seed phrases.
Sparrow Wallet (free software) on your computer for managing the multisig setup.
Note that you could also use Blue Wallet on your phone for this below instructions. I didn't specifically ask GROK this but you could, just make sure no seeds go on any online wallets only the xPubs which can be public and do not pose a security risk.
A USB drive or SD card for transferring files (air-gapped).
Option 1: Using One SeedSigner (Wipe Between Uses)
This is simpler and cheaper but requires careful seed management.
Build Your SeedSigner
Get a Raspberry Pi Zero, camera module, and display (check SeedSigner’s GitHub for exact parts).
Download the latest SeedSigner software (e.g., v0.7.0 as of now) from their official GitHub.
Flash it to your microSD card using a tool like Balena Etcher on your computer.
Assemble the Pi, plug in the camera and screen, and boot it up with the microSD.
Generate Three Seed Phrases
Boot SeedSigner, go to “Seed” > “Create Seed” > “24 Words” (for max security).
Write down the 24-word seed phrase it shows on paper or metal. Label it “Key 1.” Keep it secret and safe.
Go to “Seed” > “Export as SeedQR,” scan it with your phone or save the QR code image on a USB drive.
Shut down SeedSigner, remove the microSD, and reflash it with the software to wipe it clean.
Repeat this process two more times to create “Key 2” and “Key 3,” wiping the device each time. You now have three unique 24-word seeds.
Set Up Multisig in Sparrow Wallet
Install Sparrow Wallet on your computer (download from sparrowwallet.com).
Open Sparrow, click “File” > “New Wallet,” name it (e.g., “My2of3”), and select “Multi Signature” (2-of-3).
For each key:
Go to SeedSigner, load a seed (e.g., Key 1) via “Seed” > “Load Seed” > scan its SeedQR or type it in.
From SeedSigner’s main menu, select “Export Xpub” > “Sparrow” > show QR code.
In Sparrow, click “Add Device,” select “SeedSigner,” and scan the QR with your computer’s webcam.
Repeat for Key 2 and Key 3, wiping SeedSigner between each (or use saved QR images from the USB).
Sparrow will create a 2-of-3 multisig wallet with three public keys (xpubs). Save the wallet file.
Back Up Everything
In Sparrow, go to “Settings” > “Export” > “Output Descriptor” and save this file (it’s your wallet blueprint).
Store each seed phrase (Key 1, Key 2, Key 3) and the descriptor in separate, secure locations (e.g., safe, bank vault).
Test It
Send a tiny amount (e.g., 0.001 BTC) to the multisig address from Sparrow’s “Receive” tab.
To spend, create a transaction in Sparrow, export it as a QR, sign with SeedSigner loaded with Key 1, then wipe and sign with Key 2. Broadcast via Sparrow.
Option 2: Using Three SeedSigners
This avoids wiping but costs more (three devices).
Build Three SeedSigners
Assemble three separate SeedSigner devices as above, each with its own Pi, camera, screen, and microSD flashed with the software.
Generate One Seed Per Device
On SeedSigner 1, create a 24-word seed, write it down as “Key 1,” and export its SeedQR.
On SeedSigner 2, do the same for “Key 2.”
On SeedSigner 3, do the same for “Key 3.”
Keep each device powered off when not in use.
Set Up Multisig in Sparrow
Same as above: open Sparrow, create a 2-of-3 wallet, and add each device’s xpub by scanning their “Export Xpub” QRs one at a time.
Back Up
Save the Output Descriptor from Sparrow and store each seed phrase separately with its device number.
Test It
Send a small amount to the wallet, then sign a transaction with any two of the three SeedSigners.
Signing a Transaction (Both Options)
In Sparrow, go to “Send,” enter details, and click “Create Transaction.”
Export the unsigned transaction as a QR code.
Boot SeedSigner with Key 1, scan the QR, verify details, sign, and save the signed QR to USB.
Repeat with Key 2 on a wiped SeedSigner (Option 1) or second device (Option 2).
In Sparrow, import both signed QRs and broadcast the transaction.
Tips for 100k+ AUD
Diversify Storage: Keep Key 1 at home, Key 2 in a bank vault, and Key 3 with a trusted family member.
Add a Passphrase: On SeedSigner, you can add a custom passphrase to each seed for extra security (write it down separately).
Practice First: Test with small amounts until you’re comfortable.
Stay Air-Gapped: Never connect SeedSigner to the internet or type seeds into a computer.
This setup gives you a secure 2-of-3 multisig wallet. With one SeedSigner, it’s cost-effective but takes more steps. With three, it’s faster but pricier. Either way, you’ve got no single point of failure—perfect for big holdings.