Public key as Identities

In blockchain and cryptocurrency world.

What is public key?

Public key cryptography or asymmetrical cryptography, is any cryptographic system that uses pairs of keys: public keys which may be disseminated widely, and private keys which are known only to the owner(holder).

This accomplishes two functions: authentication, where the public key verifies a holder of a signed message(signed using private key), and encryption, where only the paired private key holder can decrypt the message encrypted with the public key.

Blockchain only deals with Digital Signatures thus with the authentication part.

What makes public key an Identity?

In real world scenario, your bank account number or your phone number is your identity. Similarly, in blockchain a signed message (e.g. transaction) uploaded by an entity can only be verified by using entities specific Public Key. If you see, the public key acts as an actor or a party in a system which can make statements by signing those statements as valid. Thus, if public key is unable to verify that signed message then that message is considered invalid.

If you know private key that corresponds to a public key. Then you can sign messages using private key and publish it onto the network, but what you are basically doing is making statements on behalf of that public key.

Advantages of public key as identities.

This brings us to the idea of Decentralized Identitiy Manangement System. Such that, one can register as a user in the system with out having to register in one central place, like one has to go through registration while opening an account in bank or signing up in a website.

These identities are call addresses in cryptocurrency jargon (e.g.bitcoin). Which is only a public key or hash of a public key.

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