Bitcoin Forum

My question is simple. If i have an online wallet and then i change the password of this and not spent any bitcoin from that time do i have again a cold wallet?

You question is completely flawed as 100 online wallets could do things in 100 different ways.

You might want to think about your question a bit more if you want a serious answer.

If you have your coins and private keys on an online wallet like say Blockchain.info, Coinbase, or Circle, pretty sure it's still a hot wallet.

Only true Cold Wallet, is an always offline PC or storage hard drive, or the safest bet, a paper wallet.

I mean online wallt the bitcoin-qt official wallet that i have spent from there some bitcoins

As long as Bitcoin QT connects to the Internet at any point, makes it a hot wallet.

Doesn't matter if you changed the passphrase or password you used to encrypt it.

Cold wallet = never touches the internet

cold wallet is never sync with the blockchain?

If you are changing your passphrase for your bitcoin-qt wallet then you will still need to move all your balance to a new address (assuming your concern is someone being able to crack your old passphrase).

I am pretty sure that the unused private keys in your key pool are discarded at the point of changing your passphrase so after changing the passphrase (and making sure you keep a backup of your old wallet) send the funds to a new address (and of course backup again).

And as others have already pointed out - bitcoin-qt can't do cold storage unless you are running it from a computer that isn't connected to the internet.

Always assume that there is another person on your computer watching what you are doing if it is connected to the Internet.

Plan your Bitcoin storage accordingly.

Hmm, now I understand what it's cold wallet..., :)

And the next question is this. A cold wallet can transfer some amount of bitcoin to trezor for time to time and remain a cold wallet?

buy a cheap and secure hardware wallet like this one:

http://www.coindesk.com/ledger-launches-usb-bitcoin-wallet-bank-grade-security/

an online wallet can't ever be a cold wallet

I suggest you keep a small amount of bitcoins in your hot wallet for your day by day use. And the most part of your bitcoins (your savings - cold storage) you may want to keep in several paperwallets (you would not keep the total amount in a single paper wallet, but better, you'll divide your bitcoins into as many different paper wallets as convenient). This way, every time you have to touch your "cold storage" (the bitcoins from your savings) you should import the private key of the paper wallets you will spend the funds from. If, after spending it, there remais a change, you can either keep it in your hot wallet, or send it to a NEW paper wallet.

That's what I do... at least.

I don't think that word means what you think it means.


A cold wallet is a wallet that is not connected to the internet, has never been connected to the internet, and never will be connected to the internet.

As soon as you connect a wallet to the internet, it is no longer a cold wallet.

thx everyone for the answers :) My question remain. If a wallet is not sync with blockchain how can i trust that my assets is not somehow corrupt in the future? Is not danger to have a wallet that is not even sync with the blockchain?

Yet so difficult to understand...

Sorry for my ignorance and i am sorry if i disappoint you.. :P

My guess is that you are *learning* now - so do some more research into cold storage in order to properly secure your BTC (and there are numerous forum members who can help guide you here).

You either trust your wallet to properly generate private keys and the correct address for each private key, or you don't.

If you trust the wallet to properly generate private keys and the correct address for each private key, then you can use any block explorer or any "watch only" wallet to calculate the total sum that you control. Therefore, there is no benefit to having the wallet sync.

If you don't trust the wallet to properly generate private keys or the correct address for each private key, then it won't matter if the wallet it hot, cold, sync, or not sync.  If you sync a wallet that is generating the wrong addresses, then how can you trust that your assets are not somehow corrupt? Therefore, there is no benefit to having the wallet sync.


What danger are you afraid of?  Please describe the specific danger that you think might happen to your offline wallet.  Then perhaps we can help you figure out how to protect against that danger.

I mean if you store your bitcoins in a cold wallet and then we have in the future a fork of bitcoin for some reasons like technology upgrades etc can the forked edition handle this old adresses?

Bitcoin development is now very conservative so I would not be too worried about that - if there was any reason why addresses would need to be changed (such as ECDSA being cracked) then I'm sure you'll know about it before it is too late.

It will have to.  If it can't, then nobody will be able to spend any of their bitcoin ever, since there will be no way to spend it out of the old addresses into the new addresses.

This might sound a bit scary if its the first time you've heard it but: There are no actual bitcoins, and there are no actual addresses at the technical level of how bitcoin operates.

The way the protocol works is that the blockchain stores transactions that list unspent outputs that are to be spent as inputs and new outputs that are to become unspent outputs.  The inputs supply a sum of value to the transaction.  The new outputs encumber that value with requirements.  The most common requirement that an unspent output is encumbered with is a requirement to supply an ECDSA digital signature which must be verifiable with a specific public key.  The public key is identified by its RIPEMD-160 hash, which we convert to an "address" to make it easier for humans to work with.

Therefore, anybody that can provide the proper ECDSA signature can "spend" the value associated with the output.  If the protocol changes in the future to allow a new way to spend outputs, then new outputs will need to be created that have this new encumbrance. The only way to do that is to first spend the old output by supplying the proper signature.  Therefore, nobody will be able to move any of the value to the new encumbrance unless the protocol continues to allow users to spend the existing outputs that have the old encumbrance.

thank you so much :) Was really educated this post.

Easy. Check your public address on the blockchain. That will tell you how much is in your wallet without bringing your wallet online.

Dude, thanks dude.. Now you scared me: what if my cold storage doesn't have the correct private key.. I'm gonna have to make a small transaction to verify!

Your public key (aka your address) is calculated from your private key. As long as whatever you used to generate your private key properly calculated your address, then this is not an issue.

The public key and the address are not the same thing. The address is generated from the public key.


Correct.


Exactly.  If you trust the software to properly calculate the address, then it is not an issue.  If you don't trust the software, then you might not want to use bitcoin at all until you find software you trust.

classic "senior" moment this post is