A private key is needed to access and spend bitcoins. A Bitcoin address is comprised of two parts, a public key that can be given out to others and is stored on the Blockchain. Then there is the private key, which is required to ‘sign’ a transaction, like signing a cheque.
A private key is all that is needed to spend your Bitcoins. But, as the name suggests, it must be kept private.
How to Generate a Private Key
A private key is usually generated in wallet software and is transparent to the user. A private key can take the form of a 12 or 24-word master seed. (MUST BE KEPT PRIVATE) It may be a list of public/private keypair. Each new address has its own private key.
However, you can generate your own private keys with a website such as bitaddress.org, which is a private key generator. These can then be printed and stored offline.
If you use a wallet service such as coinbase, they manage the private keys for you.
How Secure is A Private Key?
A private key, if stored properly, is impossible to brute force with current computing technology. An exhaustive search for a private key would take more than the age of the universe to crack.
To try every possible key would take over 2,000 trillion years. Some puzzles have created easier to crack private keys by programs such as bit crack. There are instances in which a flawed random number generator was used to generate keys, resulting in lost funds. For this reason, you should only use a trustworthy wallet software. You cannot crack a regular private key with bitcrack
The main risk in private key security is the private key being stolen/hacked from a machine. This could be a virus on a computer that exposes a desktop wallet when it is used or when a user is tricked into entering their 24-word seed into a fake version of their wallet program. Be sure to research the websites used, and no seed phrase should be entered into a browser.
If you are storing a large amount of Bitcoin, a hardware wallet such as a ledger will help mitigate hacking threats.
Best Private Key Generators
The best private key generating software is a quality wallet such as Electrum. You can use offline generators for paper or cold storage. An example of such is bitaddress.org, which can be downloaded if you want more control over private keys. A list of common private key generators and wallet software is below:
- Electrum – www.electrum.org
- Coinomi – www.coinomi.com
- BitAddress www.bitaddress.org (use offline)
- Wallet Generator – https://walletgenerator.net/ (Download and use offline!)
- Ledger (hardware wallet and key generator) – www.ledger.com
- Trezor (hardware wallet and key generator) – www.trezor.com
The above gives the basics of private keys and how they are generated. Remember, your private keys provide access to your funds. Keep them safe and secure, and do not give them to anyone else! Also keep them backed up.