my simple way to store bitcoin - is it any good

[nomad647]

hi, i'm new, no experience, i'm buying bitcoin on exchanges

i want to cold store without using hardware wallet.
(i've tried keepkey and it is too complicated for me)

my idea is to use, say a coinbase wallet,
keep 12 words safe & not upload backup to cloud
then transfer all my bitcoins from exchanges to wallet
then delete the wallet

then all i need to do is keep my 12 words safe for many years on metal plate
i tested by opening another different wallet  (bitcoin.com),
then, using these words, all my bitcoins appeared
is this safe to do and still work again in say 10 years

[jackg]

Yeah it's safe, from online attacks. As long as you dobt broadcast what it's for, you produce the phrase from an offline computer and test its reproducibility (apsi make a note of the derivation path anywhere as there are a few different standards).

[AB de Royse777]

my idea is to use, say a coinbase wallet,
keep 12 words safe & not upload backup to cloud

Coinbase, Blockchain.com type wallets are already online.
When you are creating a wallet in an online service or when a wallet is online then you are already on the cloud :-P

Download electrum , make sure you verify the downloaded file. Disconnect internet from the device and never go online from the same device unless you reset the window. You can also take the software in an offline device which will never go online in the future. Install it.

Create a wallet. The wallet you have now is safe since there are no online connection since you have created it. Write down the seed in a paper, or do something so that you can get them for restoring the wallet anytime you want in an offline device. Delete the wallet from the device.

Now you have a wallet that has not gone online.

[nakamura12]

Yes you can do that too but just make sure you didn't share your 12 words to anyone but to yourself or else your bitcoin will be gone. You can also do what Royse777 guide to have a wallet that is not exposed to the internet yet. I also used electrum too but mostly I use my local wallet to received bitcoin.

[nomad647]

thank you for replies.

so what does it mean "as long as you don't broadcast what it is for"

so are you saying, the seed words created in a coinbase wallet are not secure

and if i use electrum wallet to create the 12 words,
how do i get my funds into the seed words without going online
do i use the coinbase wallet with the electrum seed words?

[o_e_l_e_o]

is this safe to do and still work again in say 10 years

It's a good idea in theory but there a few mistakes in your implementation.

First of all, the wallets you have chosen. You are choosing third party, online, and closed source wallets. These should be avoided. Far better to use an open source wallet do this, such as Wasabi or Electrum. (Caveat with Electrum - the seed it generates will not be a BIP39 seed, and so will need to be restored to Electrum in the future).

Second of all, testing your seed phrase by restoring it to a wallet on an internet enabled computer exposes it to the internet, and so it is no longer safe to use.

The best way to solve this is to use a computer which will be permanently airgapped - i.e. never go online again. An old laptop you have lying around would be perfect. Format it, install a clean OS, transfer your chosen wallet software to it via USB drive, create a wallet, back up the seed phrase, send your funds to the first address (double triple check the address!), and then delete the wallet (and for extra security, format or even destroy the hard drive).

so are you saying, the seed words created in a coinbase wallet are not secure

Correct.

do i use the coinbase wallet with the electrum seed words?

Absolutely not. Lets say you follow my instructions above and use Electrum to create a new wallet on a permanently airgapped device. That wallet will generate for you a number of addresses. You can either scan those addresses with a QR reader or simply copy and paste them in to a text file and save it on USB drive. That way, you can transfer the addresses to your internet enabled phone or computer. Then you can use them in a transaction to send your funds to. Alternatively, you can export the master public key which will provide you with all of the address in that wallet, rather than just copying individual ones.

[AB de Royse777]

how do i get my funds into the seed words without going online

You need an online device and the Master Public Key of your wallet that was in the offline device. You will also need a removable device that will use to transfer files from online device to offline device and vice versa.

Create the watch only wallet using the master public key of your wallet in the online device.
Create the transaction you want and export the file. And take the unsigned file in the removable device.
In the offline device open the wallet, have the removable device connected with the offline device.
Load the file in the wallet and sign the tx then export the signed file in the removable device.
Connect the removable device to the online device.
Load the singed file in the watch only wallet and broadcast the tx.

Your wallet is not going online in any step if you follow above every time you need to send bitcoin to another wallet.

[nomad647]

ok, thanks for help.

so i think i get it now.

use electrum to create 12 words
use electrum to copy a bitcoin address to text file on usb

go to exchange, send bitcoin to that text address, (not to any online type wallet)

then get a 'watch-only' wallet, enter the address and see if bitcoins are there

and never enter the 12 words on any wallet that goes online..

[NeuroticFish]

Download electrum , make sure you verify
~snip~
Create a wallet.
~snip~
Write down the seed in a paper

Wasn't Electrum seed work only with Electrum?
Why not download Ian Coleman git source code and run that for the seed? ( https://github.com/iancoleman/bip39 )
That will work in Electrum and other current or future HD wallets too.

[Saint-loup]

Download electrum , make sure you verify
~snip~
Create a wallet.
~snip~
Write down the seed in a paper

Wasn't Electrum seed work only with Electrum?
Why not download Ian Coleman git source code and run that for the seed? ( https://github.com/iancoleman/bip39 )
That will work in Electrum and other current or future HD wallets too.

This is what I wanted to suggest.
@nomad647 What you are describing is a paper wallet. You don't need to download and install any software to create one. You can just use an offline tool like the iancoleman page for that  https://github.com/iancoleman/bip39/releases/latest/ Moreover you'll get a real BIP39 seed as NeuroticFish said.
Then you'll be able to check your funds on a blockchain explorer or a watchonly wallet thanks to your public key.  

[akirasendo17]

If you really wan't to be secure then avoid third parties, at the same time its online , all of the wallet has their own weaknessim pretty sure about that
there should be the main thing that you should do is choose a wallet that if something happens you will have a solution to retrieve it, i will not suggest any wallet, and what you're doing is correct exchange wallet is not the right place to store your coin

[Chikito]

then get a 'watch-only' wallet, enter the address and see if bitcoins are there

To avoid scammer known your wallet type (BIP39 or Electrum seed), it's not necessary to a "watch-only" wallet, you have free to not download the wallet. you can enter your address into an explorer or use address watcher to see if bitcoins are there.

[pooya87]

Wasn't Electrum seed work only with Electrum?
Why not download Ian Coleman git source code and run that for the seed? ( https://github.com/iancoleman/bip39 )
That will work in Electrum and other current or future HD wallets too.

for starters it is written in JavaScript and runs inside your browser. it can never be as secure as a stand-alone desktop application such as Electrum that is also written in python. additionally you need more features such as signing transactions when you want to spend coins, etc. so you need to have a wallet anyways. only focusing on one thing (Electrum) is better than having two different software, one to create the mnemonic and another to create the wallet.

besides Electrum mnemonic algorithm is not complicated at all, you can always reproduce it if you needed. and if you want to migrate to another wallet other than Electrum you must always send the coins to a new wallet created by that new software instead of importing the seed into it.

[o_e_l_e_o]

then get a 'watch-only' wallet, enter the address and see if bitcoins are there

If you import your master public key to the watch only wallet, then it will generate every address your seed phrase can generate, rather than just copying a single address. This will be useful if you want to top up the wallet at a later date so you can use a new address for your deposit, which is good for privacy.

Why not download Ian Coleman git source code and run that for the seed? ( https://github.com/iancoleman/bip39 )

If it were me, I'd probably use both. Download Ian Coleman and Electrum, verify them both, and transfer them to my airgapped computer. Use Ian Coleman to create a seed phrase, make a note of the master public key and the first address, restore the seed phrase in Electrum, and check the first address matches.

[20kevin20]

use electrum to create 12 words
use electrum to copy a bitcoin address to text file on usb

go to exchange, send bitcoin to that text address, (not to any online type wallet)

then get a 'watch-only' wallet, enter the address and see if bitcoins are there

and never enter the 12 words on any wallet that goes online..

The 12 words you create are the seed for your wallet. If you lose them, you lose all these Bitcoin addresses you want to copy. The only thing you should ever give someone is the Bitcoin address. Not the private keys, not the seeds. These two should only be known and seen by you. Think of the seed and private keys as the key to your house.

Remember that once you give someone an already used Bitcoin address, they will be able to verify your balance and past transactions. That means, they'll know that the address should be yours. They will only be able to watch your Bitcoin address though. To use it in actions such as message signing and spending coins, they'll need the seed and/or private key(s).

If you want to follow the replies before me and go after an airgapped wallet, then remember that the "text address" you were talking in the third row I quoted from your message is the same address you should insert into the "watch-only" wallet. But I repeat, your Bitcoin address, not the privkey or seed.

One thing I would suggest is that you use USB sticks and microSD cards between devices as least as possible. USBs are one of the easiest ways you could get a device that contains your Bitcoin wallet infected, and plugging an infected USB into your airgapped device to only plug it back into an unsafe PC is a risk. Rather than using an USB to copy addresses, you could just use QR codes with Electrum and a webcam instead.

Personally, I would first transfer only a few bucks and make sure they're going to the right place before moving all my funds to the airgapped device. Better be safe than sorry.

[Saint-loup]

besides Electrum mnemonic algorithm is not complicated at all, you can always reproduce it if you needed.

LOL I think you didn't realize that you are in the Beginners section here.  
Currently there isn't any documentation that fully describes the algorithm used AFAIK
The Electrum doc page only explains it very partially https://electrum.readthedocs.io/en/latest/seedphrase.html
And it's an issue because users can't evaluate and compare its real security if they can't read and understand the python code https://github.com/spesmilo/electrum/blob/master/electrum/mnemonic.py

[o_e_l_e_o]

There is even more simple way to get your cold address for storing bitcoin. All you need is to toss up the  coin  256 times and convert resulting random binary number into bitcoin address. There are plenty WEB sources that may instruct you how to do that. One of them is that video on youtube https://www.youtube.com/watch?v=XQ8Uz0qMtoU  Don't forget to memorize the private key (i.e. random number generated from coin flipping)  relevant to that address otherwise you will not be able to access it.

As much as I am a fan of generating your own entropy using coin flips, rolling dice, or something similar, there are a few things I disagree with here.

First of all - don't use a web source. As soon as you enter your entropy in to a website, then you have negated the entire point of creating it manually. Whatever you use to convert binary in to hex, make sure it is done offline (you can also do it manually with a simple lookup table such as this one: https://i.imgur.com/BjpomPf.jpg).

Second of all - don't memorize it. Back it up written down on paper. If you try to memorize something as complicated as a random private key, you will almost certainly forget some portion of it and lose access to your coins.

Lastly, I always think it is better to work with seed phrases rather than individual private keys. They are easier to use, harder to make a mistake with, allow you to back up an entire wallet rather than just a single address, and avoid issues with coins being sent to change addresses you cannot access. It is also very easy to use your own entropy to generate a seed phrase by selecting the box "Show entropy details" on the Ian Coleman page.

[traderethereum]

I assume you already have a wallet installed on your computer/ mobile phone, and you have your 12 words.
That will be safe as long as you don't upload that 12 words to any cloud or online server, and it is preferred to save that 12 words in separate devices or write it in the paper and save it in a safe place.
If you don't do anything with the wallet and that 12 words, and you don't send it into any cloud online, you don't have to worry because you can avoid hackers from penetrating or stealing your bitcoin.
You can work with the different wallets as you say, and you can see how much bitcoin you have in that wallet, and you can use that 12 words in other wallets.
You don't need to tell other people that you have bitcoin because that can make them curious. You can only say to the person you trust.

[Saint-loup]

it is preferred to save that 12 words in separate devices

Saving seed in electronic device is risky. It can be destroyed within no time, can be lost as well. Well, writing in paper carries the same risk but I would prefer writing in paper than saving in electronic devices. Moreover, if you are saving on devices which you need to go online, you are risking the fund as hackers may target you.

Don't spam the thread please
The real quote is

it is preferred to save that 12 words in separate devices or write it in the paper and save it in a safe place.

Then your post is pointless

[NeuroticFish]

Why not download Ian Coleman git source code and run that for the seed? ( https://github.com/iancoleman/bip39 )

If it were me, I'd probably use both. Download Ian Coleman and Electrum, verify them both, and transfer them to my airgapped computer. Use Ian Coleman to create a seed phrase, make a note of the master public key and the first address, restore the seed phrase in Electrum, and check the first address matches.

Yep, I agree, this is the best way to move forward.
Before having hardware wallet, this is also what I've done to have the peace of mind everything is correct.

for starters it is written in JavaScript and runs inside your browser. it can never be as secure as a stand-alone desktop application such as Electrum that is also written in python. additionally you need more features such as signing transactions when you want to spend coins, etc. so you need to have a wallet anyways. only focusing on one thing (Electrum) is better than having two different software, one to create the mnemonic and another to create the wallet.

besides Electrum mnemonic algorithm is not complicated at all, you can always reproduce it if you needed. and if you want to migrate to another wallet other than Electrum you must always send the coins to a new wallet created by that new software instead of importing the seed into it.

I find this a strange mix-up. You first want to make it easy to install and handle, but later on you seem to forget that not everybody has programming skills. But maybe I missed something.
However, Electrum is indeed the easy way to go, but if this seed is used, one may get a huge surprise at a later point if he tries to use something different.
So.. I still stick to my point: generate with Ian Coleman's scripts. Then, for checking it out or for easy later us if necessary, yes, Electrum (with imported seed) is the best option (until the user learns about CJ or LN, if ever).