Public vs Private Keys

12-Word Passphrases Explained
Coin Cloud Team
, published on 
September 15, 2020
Public vs Private Keys

Yesterday we talked about how to get a bitcoin address. That refers to a public address, which you can share with someone to receive bitcoin.

We briefly touched on private keys and passphrases, but today we’re going to go a bit deeper into what private keys are, how they relate to passphrases, how they’re different from public addresses, and what to do (and not do) with those private keys.

What are Private Keys?

A private key (sometimes called an extended private key) is a 64-digit string of letters and numbers, which allows you to control your bitcoin wallet.

You can move your wallet from one app to another, or import your old wallet after losing your phone, reinstalling an app or program, purchasing a cold storage hardware wallet, etc.

This key is completely personal, and you shouldn’t share it with anyone.

A private address, or private extended key, will look something like: xpty9x78WiPR356L9PDcopmRT67Z8Rnv7HToLG3UHorg25HFNpr34STyn9MN76ed

What is a Passphrase?

Because this 64-digit random string is nearly impossible to memorize, and a hassle to store, your wallet app has turned it into a 12-word passphrase, also known as a seed phrase, mnemonic seed, recovery phrase, backup phrase and several other combinations of those words.

Your passphrase is generated by your wallet and can’t be changed or re-ordered. If you lose it, and also lose your phone or uninstall your app, you could lose access to your bitcoin. So never lose the 12-word seed recovery phrase. Just don’t, OK?

But basically, it’s a humanized version of that long random string of digits. It takes the info coded in that private address and turns it into a series of words that will always be connected to your wallet, no matter how many other factors change.

It should be noted that if you have multiple currencies in your wallet app, such as Bitcoin, Bitcoin Cash, Ethereum and Litecoin – each with their own individual wallet – you may have multiple private addresses, but still just the one backup seed phrase that incorporates all of them.

A 12-word passphrase will look something like: practice feelings despair witch creek blouse cold planet shame least cruise collapse

What is a Seed Extension?

Some digital wallet apps allow you to create your own password to encrypt your seed phrase and make it harder to access. This will essentially require a 13th word to be added to the generated passphrase. It’s not advisable to store this additional word with the original 12, because the idea is to make your money harder to steal. Ideally, this would be a word that you just know, memorize, and manually add to the 12-word passphrase when importing your wallet.

How do I Save my Passphrase?

There are a few ways to save it securely, but many people recommend writing it down, old school, word by word, and keeping that paper somewhere safe. You might even want to make multiple copies. But make sure only you have access to these, because anyone can import your wallet and steal your bitcoin if they have the seed phrase. (Also make sure not to store the paper somewhere that it could become wet, catch on fire, or otherwise get destroyed.)

You can also screenshot each individual word, and keep that in a secure folder on your phone or computer. Just make sure nobody has access to it, and it wouldn’t be advisable to keep those screenshots in your camera phone’s gallery app with all your photos. Don’t email it, either, unless you’re comfortable with the possibility of your account being hacked or otherwise compromised.

If you buy a cold storage hardware wallet, it might come with a metal stamp set, engraving tool, or little letters like a kids’ word game, to store with the hardware wallet case (or in a separate location).

This allows you to permanently store your seed phrase without having to write it down. Obviously, it wouldn’t be safe to store the passphrase WITH the wallet unless the whole thing is locked away somewhere. Better to lock the wallet in one location and the passphrase in another.

Public vs Private Keys

A public key, or public address, is usually 34 digits long, and also looks like a random string of letters and numbers (because, well, that’s exactly what it is!)

A public address will look something like: 3PT6HdpK6BUhtsF2YJtmoHbWnoKB2z7Q

You’ll probably also have a QR code version of it in your digital wallet app or online account.

Public addresses can be changed for each transaction, or refreshed as often as you like. You can do this by manually requesting a new one before copying your address to give someone. Some wallet apps will also do it for you every time you log in, or on some predetermined trigger. The money will still go to you, even if the address looks different.

If you’re looking for a digital bitcoin wallet, we recommend using the Coin Cloud Wallet app. You can use it to store and protect your funds like any digital wallet, but if you plan to use a Coin Cloud Bitcoin ATM, it’s practically a no-brainer to pair it with the Coin Cloud Wallet for optimal experience.

Disclaimer: The information and views supplied on the Coin Cloud blog are for educational and entertainment purposes only. We are not financial advisors, so please do your research and consult with a trusted financial specialist before investing your money.

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