Bitcoin Forum

Hi, I've been using Blockchain .info from a while, I'm willing to switch to an offline wallet, I don't feel 100% secure with Blockchain, can you suggest me one?
And some tutorial noob-friendly that explain me how to use it?
I mean, if my PC one day stop working, I lose my BTC? Or if I use a USB drive to store BTC, if the USB stop working, I lose my BTC? I have a lot of doubts about offline wallets, if anyone can clear me that, would be great
Thanks very much, hoping in some answers  :)

P.S. Good new year!

You need backups on different devices and even paper if it's not too complicated for you.
I recommend Electrum if you don't enough space to store the blockchain on your computer, otherwise you can use the Core wallet.

Your coins will be much safer against theft or the online service shutting down if you have proper backups.

You can backup your wallet.dat file and open it on another computer. You can have the same address accessible from multiple computers/usb sticks at the same time.

FTFY. Good that you finally understood how risky Blockchain.info is.
To be fair, any most wallet can be used offline as long as its a desktop wallet.*

I believe that you would be asking for a desktop wallet. Electrum is the best desktop wallet I've ever used. Just create a wallet, secure your seeds in a safe place and you should be able to use it without any issues. The UI is pretty well designed. You can just use Electrum offline[1] and it would be 100% safe.
If you are storing your wallet file only on that device and you didn't make any other backups or have the seed of that wallet. If your wallet is a HD wallet, the seeds will cover your entire wallet and it would be enough to restore your entire wallet.

[1] https://bitcointalk.org/index.php?topic=1559277.msg16904498#msg16904498
or
http://docs.electrum.org/en/latest/coldstorage.html

* Read devans's post for more clarity. Thanks devans!

ranochigo's comment contains some valuable advice, but I feel the difference between desktop wallets and offline wallets should be clarified.

A desktop wallet is any wallet that runs on your computer (duh). Most desktop wallets are also online wallets in the sense that they require direct access to the internet.

An offline wallet on the other hand is never connected to the internet. Its private keys are generated offline and transactions are signed offline. Not all desktop wallets are offline wallets, but most (all?) offline wallets are desktop wallets.

Electrum is capable of both and a fine choice!

Back up your private keys or secret seed on both a USB and paper in different places. Practice importing and exporting keys from your USB and from paper until you are comfortable that you 100% know how it works and how to recover your funds if you computer blows up tomorrow.

So, I downloaded electrum on my notebook, but as I have understood it's better to have a separate cheap netbook offline only to store Bitcoin, is that true? In this way I can't be victim of malware and I don't risk that they stole them, am I right? And when I have to use them I just connect the netbook to internet.
I'm talking about 1, 2 BTC, not very much, is that a good solution?
Then I saved the 12 words and I used 2 factor authentication wallet (TrustedCoin with Google authenticator, is that safe?)
P.S. If for some case I lose access to the Google authenticator and the netbook, I only need the 12 words to recover the wallet right? So, if that's true, the wallet is also stored online or am I wrong?
If you have other advises tell me, please
Thanks very much for all these answers guys and sorry for too many questions, but I wanna be secure in storing my Bitcoin

P.S. 2: After all, I just send Bitcoin from blockchain.info to electrum wallet address right?

A raspberry pi would suffice but yes.
Yes. But you can always use a separate online computer to script the transaction before transferring it to your offline computer to sign it. Then, transfer it back to your online computer and spend it.
Yes, yes and yes. You can't use 2FA with Electrum offline. Electrum signs your transaction with one of your keys before transferring it to sign with Trustedcoin when authorised.

Some things are not still clear.
How can I create a offline wallet if the PC with the offline wallet will not be ever connected to the internet?
So, to create a "offline" (?) wallet I take this Netbook or Raspberry PI 3, connect to internet once, create an 2Factor Authentication wallet Bitcoin, backup seeds on a paper, exporte private keys on a safe crypted USB (right, or I don't need to backup exported private keys?), then I send Bitcoins from Blockchain. info to Electrum address, then I'm 100% sure?
I still don't understand how can be offline if I create it online, this concept is not clear, I mean, the Bitcoin are saved on the PC itself, so can't be stolen if I'm cautious? I can connect it to the internet btw once in a while, I'm safe here, but I wanna be 100% sure that Electrum and other sites do not own my bitcoins like online wallet do
And I only need seeds, not private keys?
For example, if I lose everything to access my wallet, keys (still don't know if I have to backup and don't know how they work :( ), PC, Google Authenticator, literally everything except for the 12 words, and 10 years after I decide to restore my wallet with the 12 words, can I do that, right? I mean, so, I only need those 12 words and I'm 100% safe that I can restore my bitcoin in future or immediately

Also what is better Electrum or Armory as offline wallet?

You have to download the software on an online computer, verify the software, move it to a USB drive, and then install the software from the USB drive to your offline computer.

No. You do not ever need to be online to create Bitcoin addresses. There is no need to create an account anywhere, you don't need to do that.

There is no such thing as a Bitcoin that is saved. All that you need are the private keys.

No. That defeats the purpose of an offline wallet.

Desktop wallet software means that the people who made the software have absolutely no control over your Bitcoin.

You need the private keys, but with HD (Heirarchical Deterministic) wallets, you have some sort of master private key from which all of your private keys are derived from. That master private key can take the form of a seed mnemonic.

So long as there is software that supports that type of mnemonic and the same derivation process, then yes.

Depends on your use case. If you want privacy when spending, then you should use Armory. If you want ease of use, then Electrum. Electrum supports the BIP 32 HD Wallet standard whilst Armory does not (it still uses an HD wallet though).

As I said earlier, there is no such thing as a "Bitcoin" that is saved. What happens is that when you receive a Bitcoin, you are actually receiving an output of a transaction. That transaction output is stored in the blockchain (it is part of a transaction included in the blockchain). The output requires a valid signature from the private key which maps to your address. Therefore what you need to keep safe is your private key, and that is what goes in the offline wallet and never touches the internet. Your offline wallet has no idea what outputs belong to you, nor does it need to know that.

When you create an offline wallet, you also create watch-only wallet. This watch-only wallet only contains the public keys and the addresses so that the watch-only wallet can be online to watch for any transactions that pertain to you. You use that online watch-only wallet to watch for transaction outputs that belong to you and when you want to spend, it builds an unsigned transaction which you must take to your offline machine to sign with the private keys. Then once it is signed, you take the signed transaction back to the online machine and broadcast it.

Yes.

Yes

Thanks very much guys for helping me and all these answers!

Just one last question, but I don't know if it's the good place to ask that, I gave a look to the Chuwi HI12, is that a reliable 2 in 1 or it's low quality and I risk it will break or something, I'm willing to use it as offline wallet and offline media player

Have you thought about getting a Trezor (or some other hardware wallet)? Saves a lot of hassle and it's a very secure way to hold and spend bitcoins. Either way, I'd probably recommend Electrum or as a mobile option Mycelium. Those are pretty much the one's that I use and none has failed me yet (except perhaps Electrum with constant syncing problems but I was too lazy to look into it).

I wouldn't hold much on a mobile device...phones are not 100% secure.

Who said about holding much? Besides nothing is 100% secure.

PS. I spend coins from Trezor using the phone so that does make it quite safe.

 ;D

Whatever you use, I highly suggest a minimum of 3 points of protection.

Ideally 5 or more.

Its really hard to keep your bitcoin. Its up to the owner how they manage the risk. Theres a hole for every wallet. If you use paper wallet. It could lost or burn. If you use online wallets. Its prone from phishing, you cant access your private keys and it has third party. Offline wallets. You need a clean pc and good antivirus. But if your pc is broken, you lost your btc. See. Even if you have a good wallet if the owner is careless, its not effective.
I guess the only safe is cold storage.

If you want a software wallet I'd suggest you use either:
electrum (http://electrum.org) - which is a wallet that stores your addresses and private keys on your computer (the private keys not beign owned or seen by electrum's central servers AT ALL).
or
Bitcoin Core (http://bitcoin.org/en/download) - although it does require at least ~110GB to download the full bitcoin blockchain.

(With an electrum wallet, there is a simple way of exporting your addresses and private keys to a CSV format and electrum is probably more secure as there is more protection - your private keys are encrypted using a seed, the seed is encrypted using a password. Therefore, a strong enough password will make it extremely difficult to hack your wallet).

There is no problem with keeping you bitcoin as long as your pc is protected with good anti virus as well. For me offline wallet is useless if you have a problematic pc unit and i can only suggest that you must keep it to your online wallet and make sure you choose the safest wallet online and remember always not to share your peraonal infos to avoid your account to be hacked. With my experience i cash-out my btc from my online wallet to the trusted bank of my country which is their affiliate and saved that through my savings account as converted fiat currency. If ever i will invest another btc i must cash in again to online wallet in order to be converted to bitcoin again and so on i can invest at profit gaining sites which earns btc.