Topic: Storing Bitcoin about 20 years and is offline paper wallet (Bitaddress) secure? (Read 304 times)

My opinion on this: you mentioned Ledger - absolutely avoid. It is closed-source and relatively low-grade build quality, so I'd neither trust its key generation, nor that it will function in 20 years.

What you want is a securely generated seed phrase and storing it safely.

As for part one, I'd recommend using something like a hardware wallet with open-source software and (!!!) hardware, so you can be sure there is no funny business going on with key generation. Alternatively, roll dice. In that case, you need an offline, airgapped PC with Electrum; for that, just get a copy of Tails and follow for example this guide.

For safe storage, I'd probably do a few Steel Washer backups and store in different locations. Choose material to your liking (e.g. anti corrosion or whatnot) and if you want, test those properties before deploying the backups.

Do make sure to verify your backups before sending 0.5BTC to the wallet. To do this, note your first address in the newly created wallet. Then reboot the PC, import wallet in Electrum, enter the seed words from your backup and check whether the first address matches. Feel free to do this a few days later, when the phrase has fully left your memory.

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Since this has been mentioned: plausible deniability is definitely your best friend. Try to minimize the number of people knowing you own / buried BTC and the number of people seeing you do it (preferably both equal to zero).

Your tattoo artist is going to love it!

*Sorry for my translation into English via google

I give my vision.

A) Offline auto mode and with usb live
1-With a secret word, generate a SHA-256 hash-o phrase (eg mother's love) https://xorbin.com/tools/sha256-hash-calculator
2-Generate a seed phrase of 24 words https://iancoleman.io/bip39/
3-If you have hair on your head (or in another private place), you shave your hair to zero.
4-The secret word is tattooed under shaved hair.
5-Letting hair grow

*To obtain 8 seed phrases derived from the same 23 words, Convert the words to decimals and give 256 bits. The last three bits are changed. For example, if they use 253 bits and the last 3 will oscillate between 000 and 111 (8 possibilities) and 8 seed phrases can be obtained,
Then save as Franky1 indicates a super backup copy.
Even metal can be marked in binary

To make more entropy with the SHA-256 obtained. It can be done as many times as you want. For example:
bormi = d696f210b808e584b12ecc5c4ae2596bf5925b920b96c27d913f734459438f
Then another SHA-256 give this result = d113a18bb3c67083920dd0241cae876610f32b73bbe35de26c1166dc180910c3
So the secret word would be bormi*2

As I already said, there shouldn't be any problem since your wallet should send back the remaining balance to you.
What I said about not specifying the change address when making the raw transaction applies to any transaction, not only spending from a paper wallet.

grandma's body 6foot deep with a tombstone marker of where to dig.... is not really a deterrent if the treasure is worth enough(grave robbers)

however doing a borehole of 50ft deep. is more of a deterrent. and also cheaper to bore and bury without leaving a tombstone marker to give away where the treasure is

just saying

I think OP's plan is good but as stated by few, paper storage can get way obstructive in the future and in the long run it could be harmful as you may loose the data. I mean even one letter from the print getting lost is losing of your whole bitcoins stored on it. There are many modern ways to do it and way secured than we predict. Hardware wallet can really do this job easily and I do not think we have to overthink about it in the long run. I think we can still go with the flow and modern ways of securing our funds. I mean I am not saying go online with our ledgers. You can always generate an address from the hardware wallet and never plug it until your target is achieved. You can keep funding the address and be secure all the time.

It depends on what kind of grave your relative has, there are a lot of graves with enclosed areas with ground soil through the stone to limited area. That person can bury it deeply under the soil. Easy right? And I think that's a pretty safe area.

note about 3:
a. getting local permit to exhume a relative from their grave
b. to get the grave exhumed
c. to then put metal under their coffin
d. re-bury the coffin

and you call that less of a pain in the ass compared to printing some PDF or saving PDF to some USB sticks ?

I think that it's a pain in the ass to save 50x wallet address, then create 50x pdf, then transfer it into 10x usb, do this, do that, etc.
This is simple and pretty good idea:
1. Buy a Cryptotag Zeus - Click here. Here is the video - How to use cryptotag.
2. Record recovery words and close.
3. It may sound unethical but I think that you can feel safe if you bury it under the grave of your old relative and save there. I think that it can be safe this way and you won't have a need to do tens of wallets with divided bitcoins.

Regarding storing bitcoin for the long term some people think the most important thing and hardest thing to do is to be able to hold bitcoin even when the price spikes and does sharp movements while I think when we are talking about holding for the long term the important thing is how and where you want to hold your assets, I think where ever you hold the bitcoin you will still need to check and make sure your wallet is safe time by time so holding in underground by writing recovery seed of paper won't be a good solution and amount all the option I would use the please of paper and check the recovery seeds and wallet time by time to make sure my bitcoins safe for long term.

This seems somewhat terrifying if we consider that this hypothesis is possible if a paper wallet is used with a single address and key. This brings us to the conclusion that using this method of storage is very dangerous without the user having the necessary technical knowledge.
Also, generating 50 addresses in the same way would cost a lot of fees, even if he wanted to send bitcoins to all addresses in one transfer. In this case, he has to receive the entire amount on a wallet that enables him to make multiple transfers. Not to mention the time it will take.

Now that I'm back at my keyboard, some thoughts:
I'm not sure how serious you are about 50 ft deep, but that could make people very curious.
Creating 50 different addresses means you'll have to pay transaction fees 50 times in the future. Depending on fees, that may or may not be a lot (the highest I've paid was about 0.001 BTC in fees back in 2017, and that would be 10% of each wallet.
Don't worry about hardware wallet compatibility, worry about being able to restore the private keys without the wallet. iancoleman.io makes that possible (of course, take precuations and don't just use your regular computer). So if you want to put anything on a flash drive, download that software!
I wouldn't call an unencrypted PDF on a flash drive safer than a printed page. Get a cheap dumb (laser) printer, connect it by cable, and (when dry) the paper will last hundreds of years.
BIP38 is very strong encryption. If you lose the password, you won't be able to crack it. For consideration: you can use both: print the same paper wallet with and without encryption, one as a convenient backup, one burried 50 meter deep. If you forget your password, get a shovel.
If you start digging holes, you may not want to burry all of your wallets at the same place. Remember what happened to +34° 59' 20”, -106° 36' 52”? Dig multiple holes!
If you're really going to trust flash drives for a long time, don't get them all from the same brand. Some may last longer than others.
Coinbase probably charges high withdrawal fees, so you'll have to create a "pay to many" transaction by yourself.
If you worry about quantum computers, the world has bigger things to worry about first. The entire banking system and economy for instance. You'll have time to dig up your coins.
Will you still have access to your digs in 20 years? Any chance they'll build a highway on top?

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As a test: create a paper wallet. Encrypt it. Store it. Remember the address.
Turn off your computer, start over. Get your paper wallet. See if you can recover the private key that generates the address. This shouldn't cause any problems, but you should test it to make sure.

Thanks again for the many responses.

I've heard that Ledger is one of the best hardware wallets out there - on the other hand, I don't know whether they can be trusted after the well-known data leak from 2020?

https://www.bleepingcomputer.com/news/security/physical-addresses-of-270k-ledger-owners-leaked-on-hacker-forum/

If anyone has a good recommendation for a trustworthy hardware wallet that works very well with Electrum (offline) and doesn't require a rocker science degree, thanks a lot in advance.

Everyone have contributed with their opinions here and so far, I believe every important thing has been said.

Two points:

1. Don't trust flash memory. It is not good for long-term storage. The most durable is the HDD. However, due to moving parts that exist in HDDs, you shouldn't put pressure on them.
2. If you generate 50 paper wallets, you will need to backup 50 private keys. It is doable, but not the best choice.

Why don't you do the following:

1. Buy an airgapped hardware wallet, like blockstream jade, seedsigner etc.
2. Create a wallet, totally offline.
3. Make 2 backups of the seed phrase.
4. Store the backups in different locations.
5. Generate an address.
6. Save the address on 2-3 places, so you don't need to open the wallet again.
7. Send BTC to this address.
8. Repeat step 7 as many times as you want.

In 20 years:
1. Turn on your device, if it still works. It should have the private keys in it. So you can do whatever you want.
2. If the device doesn't work, you can order a new device from the same company and recover the wallet.
3. If the company doesn't exist anymore, you can enter the seed phrase in any wallet you want and recover the funds.

Bonus point: You can create a watch-only address in your mobile device so you can see daily that everything is ok with your hardware wallet.

I believe keeping the private key or the seed phrases in the hardware wallet and keeping a tangible backup is a good approach.  We all know that using hardware wallet gives securities but in case of gadget malfunction, we should have a tangible backup such as paperwallet (it is up to you if you will use wood or metal in engraving your seed phrase or private key)  You can also use softwares to encrypt your private keys.  You can also use a multi-signature wallet and split the private key among multiple devices as it increases the security of your created wallet a fail-safe method in case your backup got compromised.  Just make sure that the backup is securely placed in a rustproof, waterproof, and fireproof place.

There's a dozen ways to do it, one of them being lamination. There's many places where you can do it cheap within seconds and to get into the card you just need a knife or a pair of scissors and it's unsealed.

The cheapest way is to use a simple plastic bottle to store your USB drive if water damage is what you're mainly afraid of.

With a few bucks you can buy a metal container like this
Then you can simply drill a hole in the floor or a wall and put it there. It's going to last forever, as long as the house doesn't get bombed or demolished.

Generally, if you make a raw transaction and spend a partial amount without specifying an extra output as the change, all the remaining balance goes to miners.
Assuming you use a UTXO which is worth 1 BTC and send 0.5 BTC without specifying the change address, 0.5 BTC would go to the recipient and 0.5 BTC would go to miners as the transaction fee.
Of course, there shouldn't be any problem if you don't make the raw transaction yourself and it's made by your wallet.
For example, if you import a single private key into electrum and make an imported wallet including only one address, the change is sent back to the sending address.

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Right. All you will need to recover your wallet is your seed phrase. Your seed phrase can generate all your private keys.

I like how thorough you are, but I think you're over complicating things and putting too much long term trust in flash cards.

LoyceV: read this from desktop!

To start:
Don't make up your own seed words, it won't make it safer but increases the risk of messing up.
Whatever you choose, test it with a small amount and see if you can recover your coins before funding more.

Thanks again for the many helpful replies that got me thinking.

If I'm going to go the hardware wallet path, Electrum + Ledger Nano is the way to go? It's like 99% of everyone here does it?

And I can also use offline laptop + Ubuntu DVD for the setup up for additional security? As I've said, I'm only interesting in creating some offline wallets, then sending my Bitcoin from Coinbase to the wallets and then keeping the Ledger away for many years.

The only thing I have to worry about is the 24-word seed phrase and keeping it safe? Maybe I will use different and rarely-used languages for more safety regarding the words.

If the Ledger USB devices doesn't work anymore after 2 years or so, I don't have to worry about anything as long as I have my 24-word seed phrase? I can just buy a new one and use my old 24-word seed phrase and everything is like before and all wallets are available just through the seed phrase?

Thanks again for your help.

I agree with you on all your opinions on the topic, and I wonder, like you, why op seeks to follow the most complicated path while he can generate many addresses using one seed phrase.
Regarding the point in the quote, I have a technical question that may seem silly to some, but I really don't know it: If the entire amount (let's say 1 btc) is stored in one address, then the owner wants to send part of it (let's say 0,5 btc) to another address (let's assume that he does not own the address to which he will send bitcoins) without specifying Change address to receive the rest of the amount, what should happen in this case? Will there be a defect in the transaction and therefore the user will not be able to broadcast it? Or will the rest of the amount be returned to the same address from which it was sent?