Public Key Infrastructure (PKI) is a system of technologies, policies, and procedures that is used to create, manage, distribute, use, store, and revoke digital certificates and public-private key pairs. It is a fundamental component of many modern security systems, and is used to enable secure communication and authentication over networks, such as the Internet.
At the heart of PKI is the concept of public-key cryptography, which involves the use of a pair of cryptographic keys - a public key and a private key - to encrypt and decrypt messages. The public key is used to encrypt messages, and can be shared freely with anyone. The private key, on the other hand, is kept secret and is used to decrypt messages that have been encrypted using the corresponding public key.
PKI is used to manage and distribute these key pairs, as well as the digital certificates that are used to verify the identity of the key holders. A digital certificate is a digital document that is issued by a trusted third party, known as a certificate authority (CA), and that contains the public key of a user or device, along with other identifying information.
When a user or device wants to communicate securely with another user or device, they first use PKI to obtain a digital certificate for their public key. They then use this certificate to establish a secure, encrypted connection with the other user or device, and to verify the identity of the other party.
PKI is used in a wide variety of applications, including secure email, secure web browsing, and digital signatures. It is also used in many other security systems, such as those used for secure access to corporate networks, financial transactions, and government services.
Overall, Public Key Infrastructure is a critical component of modern security systems, and is used to enable secure communication and authentication over networks. It provides a framework for managing and distributing digital certificates and public-private key pairs, and is essential for ensuring the integrity and security of sensitive data.