What is Public-Key Infrastructure?

Public-key infrastructure (PKI) is a set of policies, procedures, and hardware-software combinations needed to authenticate users and devices online. In practice, this involves one or more trusted parties digitally signing a digital document or decentralized ledger in order to certify that a particular cryptographic key belongs to a particular user or device. PKIs play a pivotal role in creating, managing, distributing, using, and storing digital certificates, and managing public-key encryption.