Public Key Infrastructure (PKI) is an operational ecosystem that employs key management, cryptography, information technology (IT), information security (cybersecurity), policy and practices, legal matters (law, regulatory, contractual, privacy), and business rules (processes and procedures). A properly managed PKI requires all of these disparate disciplines to function together - coherently, efficiently, effectually, and successfully. Clearly defined roles and responsibilities, separation of duties, documentation, and communications are critical aspects for a successful operation. PKI is not just about certificates, rather it can be the technical foundation for the elusive "crypto-agility," which is the ability to manage cryptographic transitions. The second quantum revolution has begun, quantum computers are coming, and post-quantum cryptography (PQC) transitions will become PKI operation's business as usual.

Public Key Infrastructure (PKI) is an operational ecosystem that employs key management, cryptography, information technology (IT), information security (cybersecurity) policy and practices, legal matters (law, regulatory, contractual, privacy), and business rules (processes and procedures).