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Updated on October 28, 2026
Public key infrastructure (PKI) underpins secure digital communication, enabling organizations to encrypt data, verify identities, and establish trust across modern networks. As distributed teams manage human users, automated workloads, and cross-OS device fleets, PKI provides the cryptographic foundation needed to prevent unauthorized access and data breaches.
Key Takeaways
- Public key infrastructure uses asymmetric key pairs and digital certificates to authenticate identities and encrypt communications.
- Certificate authorities issue and validate digital certificates, serving as trusted third parties across enterprise networks.
- PKI supports essential security protocols, including Transport Layer Security (TLS), email signing, and network access control.
- Manual PKI management creates operational overhead and increases the risk of certificate expiration for IT administrators.
- Centralizing identity, access, and endpoint management into a unified platform eliminates security coverage gaps across your fleet.
What Is Public Key Infrastructure?
PKI is a system that governs the issuance of digital certificates that protect sensitive data and secure end-to-end communications. Digital certificates also provide unique digital identities to users, applications, and devices in an online world.
The basic idea behind PKI is to have one or more trusted parties electronically sign a document proving that a particular cryptographic key belongs to a specific user or endpoint. The system then uses the key as an identity for the user or endpoint in enterprise networks.
A typical PKI has the following components:
Public-Key Cryptography (asymmetric cryptography)
Public-key cryptography (asymmetric cryptography) uses a paired set of keys: private and public. A private key is secret (only known by the entity) and is used to sign the message. In contrast, the public key, mathematically derived from the private key, is available to anyone on the internet and is used to verify signatures. Messages encrypted with the public key can only be decrypted with the matching private key, ensuring data remains secure during transit.
Certificate Authority (CA)
This trusted third-party organization issues digital certificates, proving that the public key indicated on the certificate indeed belongs to the named subject. CA allows other parties to rely upon signatures about the private key corresponding to the certified public key.
Certificates
A certificate is a digital document certified by the CA, confirming that the public key indicated on the certificate belongs to the entity. The certificate has many attributes, including the subject name, public key, client authentication, and server authentication. Most digital certificates are based on the X.509 standard.
Registration Authority (RA)
This entity receives certificate signing requests and provides the certificates to entities on a case-by-case basis. The PKI system stores all the requested, received, and revoked certificates in an encrypted certificate database.
How Does Public Key Infrastructure Work?
When securing communications, PKI serves two primary roles: encryption, which makes sure that other participants don’t read your messages, and authentication, which certifies that the other party is a legitimate entity.
In the PKI context, the encryption system follows a simple two-step process:
- The client uses the recipient’s public key to encrypt the message.
- When the recipient receives the encrypted payload, it decrypts it using its matching private key.
You can also use digital certificates to authenticate servers or clients. For example, when you connect to a secure web portal like JumpCloud.com, PKI authentication works through three steps:
- The web browser connects to the server to obtain its digital certificate and public key.
- The browser checks its internal database to verify that a trusted Certificate Authority (CA) issued the certificate.
- The browser encrypts communications using the public key. Successful decryption proves the server holds the matching private key, establishing a secure connection.
Why Is Public Key Infrastructure Important?
PKI is an essential component of IT security because it helps organizations establish trusted signatures, encryptions, and identities. Below are some reasons why PKI is important:
PKI Can Secure Websites
Transport layer security (TLS) protocol is the most familiar use of PKI. TLS certificates and cryptographic authentication of the web server can help prevent man-in-the-middle (MitM) attacks.
PKI Can Support Email Signing and Encryption
The secure/multipurpose internet mail extensions (S/MIME) and pretty good privacy (PGP) are PKI-based protocols that specify message formats for signed and encrypted messaging.
PKI Can Secure Local Networks
Directory services such as Microsoft’s Active Directory (AD) integrate PKI capabilities to authenticate identities and provide other security functionalities on Windows domains.
PKI Can Secure the Internet of Things (IoT)
PKI enables organizations to safely authenticate IoT devices and safeguard data at rest and in transit.
Challenges Associated with Implementing PKI in Organizations
Despite its crucial benefits, in-house PKI deployments can create far more challenges than they can solve. For example, PKI isn’t like other technologies you have in the IT stack. You need highly skilled in-house IT teams to run it effectively. Unfortunately, finding the skill set that can run PKI efficiently is not only rare, but it’s also difficult to retain.
Many organizations still use outdated, manual methods to deploy and manage their PKI. For example, most organizations still tackle their problems with a patchwork of internal PKI and CA-provided tools. This persists despite changing ways of running IT infrastructure, from static hardware to highly automated systems.
Build a Scalable PKI Strategy with Unified Identity
Public key infrastructure requires a clear identity and access management framework to govern certificates, endpoints, and credentials efficiently. Without centralized oversight, managing digital certificates across mixed Windows, macOS, and Linux fleets creates operational complexity and security blind spots.
Explore how a unified IT management platform simplifies identity, access, and device security across your entire organization.
Frequently Asked Questions
Understanding PKI fundamentals helps IT administrators implement stronger access controls and certificate management policies. Below are answers to common questions about public key infrastructure.
What is the difference between a public key and a private key?
A public key is shared openly to encrypt data or verify signatures, while a private key is kept secret by its owner to decrypt messages or create signatures. In asymmetric cryptography, data encrypted with a public key can only be decrypted by its corresponding private key.
What role does a Certificate Authority (CA) play in PKI?
A Certificate Authority (CA) acts as a trusted third-party organization that validates the identity of entities and issues digital certificates. By signing a certificate, the CA guarantees that the public key listed belongs to the named individual, device, or domain.
What happens when a PKI digital certificate expires?
When a digital certificate expires, web browsers and operating systems immediately flag the connection as untrusted. This causes security warnings, blocks user access, and can interrupt automated workflows until a renewed certificate is deployed.
How does PKI support Zero Trust security models?
PKI supports Zero Trust principles by requiring continuous cryptographic authentication for every user, device, and application session. Rather than trusting endpoints based on network location, PKI ensures that every connection is explicitly verified through valid digital certificates.
Can PKI manage cross-OS device fleets?
Yes. PKI protocols like X.509 certificates authenticate endpoints across Windows, macOS, Linux, iOS, and Android devices. Integrating certificate management into a unified endpoint management system allows IT admins to deploy and rotate certificates automatically across all operating systems.
