The public key is an identifier that we can share at will that allows us bitcoins and cryptocurrencies by third parties. It is one of the two parts that make up the set of keys created by asymmetric cryptography to share secrets securely.
La public key, is one of the two keys generated by a asymmetric cryptography. It receives this name, by its name in English, public key. Asymmetric cryptography is a crucial component for the operation of cryptocurrencies, like bitcoin. Without it there could be no cryptocurrencies as we know them. This system allows us to generate a pair of keys that are no more than two cryptographically linked text strings. These keys are called: private key y public key. In this explanation we will focus on the second of them.
Something essential that we must understand is that; the private key and the public key are mathematically related. In fact, the public key is always generated from the private key. This makes both keys directly linked. However, it is impossible to calculate or deduce the private key from the public key.
Public key use cases
One of the main cases of use of public keys is in the sending and receiving of encrypted messages. To better explain this, imagine the following case:
Felipe wants to send an encrypted message to Julián. To do this, Felipe encrypts the message using Julián's public key. Thanks to this, only Julián will be able to decipher the message. To do this, Julián will use his private key, which he has never revealed and has served to create his public key (the one he gave to Felipe). With this, Julián reads the message, and can respond in the same way to Felipe.
Under this scheme, Felipe and Julián can share encrypted messages with the complete certainty that only the appropriate recipient will be able to read the message. In addition to this, Julian can also sign the message to send with his private key, so that Felipe knows that it has been written. by Julián, and has not been altered or supplanted. To do this, it will check the text with Julián's public key.
In the same way we can do. We can give our public key to our friends, family, neighbors or a stranger in the other part of the world. These people can use this key to encrypt the message and send it to us. All this with the security that only we will be able to decipher the message when having the private key. While our public key can be shared without major problems.
How does all this affect cryptocurrencies?
Cryptocurrencies take advantage of this great potential of cryptography for the generation of Bitcoin addresses. All this with the aim that it can be shared publicly. However, cryptocurrencies like Bitcoin use an optimal algorithm for the purpose of creating the address, this method is called ECDSA (Elliptic Curve Digital Signature Algorithm).
Due to the operation of asymmetric cryptography, we can get addresses Bitcoin that can be delivered to everyone without risk of accessing your funds. This is because only the owner of the public key (which in theory should also be the one with the private key) will have access to the cryptocurrencies to manage them as they consider best.
In fact, Bitcoin Simplify this by doing an address conversion, where in reality sharing the address where to receive the bitcoins, it is the software that is in charge of preparing the transaction so that only the recipient can access the funds because it is the only one that has the key private.
This protocol, which may seem difficult to understand, offers high security and guarantees that no malicious external agent accesses our money to steal it.