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14 votes

How do I protect my paper wallet from use by a different human who has used a random generator?

"Improbable" is an understatement. There are 2256 possible keys. In the entire universe, there are estimated to be "only" 2100 atoms. So the odds of someone else ending up with the exact same ...
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  • 1,334
13 votes

What kinds of wallets are there?

Can I get short a explanation about cryptocurrency cold/hot wallets? Hot wallets These are any kind of wallet that has a network connection and so is vulnerable to attack and is relatively unsafe. ...
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11 votes

What kinds of wallets are there?

Hot and cold in this case refer to if the private key is stored on a system connected to the internet or not. Hot wallets are stored on system connected directly to the internet. This can be on the ...
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  • 316
9 votes
Accepted

What is the safest physical to store a private key only to be accessed after death?

If you are comfortable with a command line, I have used ssss-split and ssss-combine for sharding encryption keys in a n-of-m scheme. These utilities use Shamir's Secret Sharing Scheme to safely break ...
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  • 8,724
8 votes

Is it possible to send coins WITHOUT importing private key?

Basically what Murch said. You have to use the private key to sign the transaction. There is a point I want to add, however. It is possible to send coins without importing the private key into a ...
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  • 1,104
7 votes

Can I spend/transfer bitcoins directly from cold storage?

Every bitcoin and bitcoin transaction is stored in the blockchain which is online, distributed and known by every full bitcoin node. What you have on your pc are private keys. As long as you have ...
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  • 236
7 votes
Accepted

How to send bitcoin from an offline Bitcoin Core that doesn't have a synced balance?

The easiest way to do this by importing the address you generated on the offline Bitcoin Core client into an online fully synced Bitcoin-Core. The command is: bitcoin-cli importaddress <address>....
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  • 6,898
6 votes

Is holding funds in a Bitcoin paper wallet safe?

Yes. A paper wallet is basically nothing more than your private key on a piece of paper. For usability it is often represented as a QR code though. You can make copies of it, and store several of ...
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5 votes
Accepted

Is it possible to have complete cold storage in NXT?

I don't know if this is the recommended way, but I did this by using the Send Nxt API call on an offline computer, storing the transaction bytes, and broadcasting the transaction from an online ...
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  • 66
5 votes

Can I spend/transfer bitcoins directly from cold storage?

The system you describe is similar to the way Armory suggests you use it. You can sign a transaction offline, then transfer that signature to an online computer and broadcast it. Your private key has ...
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5 votes
Accepted

How can an online wallet be more secure than paper wallets or cold storages?

I tested it by creating a secure wallet on BitGo. They gave a multisig address for deposits. 2/3 of keys are needed to withdraw Bitcoins. BitGo holds one key, you get private key and backup key. You ...
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5 votes
Accepted

How to securely store Bitcoin server-side?

The precautions you can take from an architerual point of view would be as follows: The database storing the private keys or the seeds in case of HD wallets should be running on a separate instance ...
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4 votes

BIP38 or Brain wallet?

BIP38 wallets are significantly more secure and are resistant to brute-force attacks when a decent passphrase is used. Generally the term "Brain Wallet" refers to one in which the private key is ...
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4 votes
Accepted

Transfer coins from Armory paper backup without Armory

Here it is step-by-step Run armory in offline mode (simply run armory --offline) Import the wallet into armory if you haven't already. (Import wallet, etc) (you probably don't need to do this if you ...
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  • 7,619
4 votes
Accepted

API to send bitcoins from paper/cold wallet?

You can just do it yourself instead of having to send a 3rd party your private keys. Here's one that I wrote using nodejs and bitcore-lib that takes a WIF and sends all funds to a different address. ...
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  • 5,176
4 votes
Accepted

How can I generate a Bitcoin address from a 12 word seed without using a computer?

While theoretically possible, the algorithms involved mean that it is practically impossible. You would need to compute the seed from your mnemonic word according to BIP 39, and then derive the keys ...
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4 votes

Security implications of regular saving into cold storage

Q1: Depens on how you use it. Transactions to an address does not decrease it's security. Using a cold-storage wallet and taking it online exposes your wallet and it's security. Q2: It's correct. ...
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4 votes
Accepted

Need a cold wallet. Segwit, Lightning, Fees?

Fees are not based on the value that is being transferred but rather the size of the transaction in bytes. The fee is to pay the cost of storing the data that makes up the transaction itself, not for ...
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  • 60.6k
4 votes

How do I protect my paper wallet from use by a different human who has used a random generator?

The generation of private keys is made randomly. Therefore, it is possible for someone to generate the same private key as you did. In your question, you heavily insisted that you did not want an ...
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4 votes
Accepted

Best OS for cold storage

Use TAILS Linux. From the website: Tails is a live operating system that you can start on almost any computer from a USB stick or a DVD. It aims at preserving your privacy and anonymity, and ...
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  • 9,789
4 votes

Signing a bitcoin transaction OFFLINE fails

signrawtransactionwithwallet uses the wallet for two purposes: Finding the private keys necessary to sign with (which you dealt with by importing) Finding the transaction outputs that are being spent ...
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4 votes
Accepted

How does a hardware wallet interact with the bitcoin network?

No. The hardware wallet company sometimes runs a node, but you could just as easily use a client like Electrum instead, and use Electrum nodes instead with your hardware wallet. All the node is used ...
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  • 1,982
3 votes

Is this a safe method for cold storage?

It sounds like a lot of hassle to send bitcoins because you have to re-install you offline armory each time. Also, the fact you're trying to do it on a live CD tells me you likely don't have an air-...
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3 votes
Accepted

How can an online system detect coins sent to its offline (cold) wallet?

Since version 0.10.0 bitcoind has support for watch-only addresses. Here is the text from the release notes: Watch-only wallet support The wallet can now track transactions to and from ...
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  • 8,319
3 votes

Estate planning: how can I ensure my bitcoins are inheritable?

Points for Hot Wallet Inheritability: Lower exposure to risks - use hot wallets that are BIP 39 compliant and share your 12 to 24 recovery passphrase and associated password in advance. Higher ...
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  • 2,917
3 votes

What is the best method for creating a paper wallet?

Here are a list of my best practices for creating a paper wallet. Generate all keys on an offline computer system, this ensures that you are not using an online system that could be sending your keys ...
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  • 2,630
3 votes
Accepted

Is it safer to use one type of hardware wallet of several?

Personal, I would use multiple wallets just in case some exploit is found in the future. For the more paranoid/safety conscious person, I would also place the hardware wallet in a mini faraday cage, ...
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  • 212
3 votes

How do I protect my paper wallet from use by a different human who has used a random generator?

The idea of ignoring sufficiently small possibilities is fundamental to BitCoin, and if you have a problem with it, then you shouldn't be using BitCoin (or anything else that involves a finite ...
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3 votes
Accepted

Can the Large Bitcoin Collider project 'break' into offline hardware wallets like the Nano Ledger S?

If LBC is somehow able to guess anyone's private key, regardless of how the private key is normally stored and generated, then yes, they can just spend the coins. All you need is the private key, it ...
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  • 60.6k

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