What's the difference between private and public key?


This is the first thing every newbie should learn about crypto because it represents basic and ultimate knowledge.

Private and public keys, or addresses, are a pair, once generated they always ‘’work’’ together. If you have your private key, you can always recall your public. But not otherwise: once the private is lost, it’s lost forever including the all the coins you had.

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Those keys are strings of numbers and letters, different for public and private. Once generated it’s almost absolutely impossible same address to be made from some other user. This is the merit of cryptography!

The public key is often called public address, and the private is often called private key. The reason is apparent: Public is behaving like an address where you should send or receive coins. Like if you provide a bank account where to send the funds.

The private key is the one that you have to have in your possession to access those coins - similar like you would need to have a pin code or password of the credit card.

On bitcoin blockchain all balances, transactions and times are visible, so that means everybody can see it when the transaction happened or how much coins some address has. However, to regular users that won’t say a lot, because no one can guess correctly what private key is behind it. The public address is the one you would like to share/let to be scanned if you want coins were transferred to you.

On another hand, you do not want to share private key with anyone! Whoever has private key has access to the coins. If the private key is lost or stolen (with no backup) coins are lost. So, all you want to do is to protect your private key. The private key should be the only focus of users and therefore protected, backup and always on the mind: if lost - no recovery.

Pavel Karpisek