Public Key Infrastructure (PKI)

Public Key Infrastructure (PKI) is a framework of policies, technologies, and processes that enables the secure exchange of information over networks using cryptography. At its core, PKI manages the creation, distribution, validation, and revocation of digital certificates, which are electronic credentials that link a public key to the identity of an individual, device, or organization. By combining asymmetric encryption and trusted third parties known as Certificate Authorities (CAs), PKI establishes digital trust, allowing users to verify identities and protect communications. PKI underpins many aspects of cybersecurity, including secure web browsing, encrypted emails, electronic signatures, and virtual private networks (VPNs).

How it works

  1. A user or organization generates a public-private key pair.
  2. A Certificate Authority (CA) issues a digital certificate linking the public key to the verified entity.
  3. The certificate is stored and distributed so others can use the public key to encrypt data or verify signatures.
  4. PKI includes mechanisms for certificate revocation and expiration to ensure ongoing trust.

Why it matters

Without PKI, secure communication on the internet would not be possible at scale. PKI ensures confidentiality, integrity, and authenticity of data exchanged online. It protects users from phishing, man-in-the-middle attacks, and impersonation by providing a verifiable trust chain. PKI is a foundation of e-commerce, secure government services, corporate IT infrastructure, and modern cloud applications.

Examples

  • SSL/TLS certificates securing HTTPS websites.
  • Email encryption using S/MIME certificates.
  • Corporate VPNs that authenticate users with digital certificates.
  • Smart cards used for secure government or enterprise logins.