What is a public key infrastructure (PKI)?

A Public Key Infrastructure (PKI) is a set of protocols, policies, and procedures used to manage digital certificates and public-key encryption. It provides a framework for managing the entire lifecycle of digital certificates, including their issuance, distribution, validation, and revocation.

In a PKI system, a trusted third party, known as a Certificate Authority (CA), is responsible for issuing and managing digital certificates. Digital certificates are electronic documents that are used to verify the identity of individuals, organizations, and devices in a secure and trusted manner.

PKI is used in a variety of applications, including secure email, web browsing, e-commerce, and virtual private networks (VPNs). It is also used to secure communication between devices in the Internet of Things (IoT) and other applications that require secure communication and authentication.

What is a private key?

A private key is a secret number used in public key cryptography to decrypt or sign messages. In a public key cryptography system, two keys are used: a public key that is shared with others, and a private key that is kept secret by its owner. The private key is used to decrypt messages encrypted with the public key, or to sign messages to prove they came from the owner of the private key. It is important to keep the private key secure, as anyone who has access to the private key can impersonate the owner and decrypt or sign messages on their behalf.

What is a public key?

A public key is a cryptographic key that is used to encrypt data and verify digital signatures. In public key cryptography, a pair of keys is used: a public key and a private key. The public key is used to encrypt data, while the private key is used to decrypt data.

The public key can also be used to verify digital signatures created with the corresponding private key. When someone wants to send a message to a recipient, they use the recipient's public key to encrypt the message. Once the message is encrypted, it can only be decrypted by the recipient, who holds the corresponding private key.

Public keys are typically shared publicly, hence the name, while private keys are kept secret. In blockchain technology, public keys are often used as addresses to send and receive cryptocurrency.