Building Castles in the Cloud: PKI and the Rise of Zero Trust

PKI & Zero Trust

The once mighty castle walls of perimeter security are crumbling amidst the digital revolution. In their place, a new paradigm emerges: Zero Trust. This security philosophy demands continuous verification and authorization for every access attempt, regardless of user or device origin. Key principles behind zero trust architectures are:

  • Single strong source of user identity
  • User authentication
  • Machine authentication
  • Additional context, such as policy compliance and device health
  • Authorization policies to access an application
  • Access control policies within an application

Building a Zero Trust fortress requires more than just vigilance – it demands trustworthy tools, and none shines brighter than Public Key Infrastructure (PKI).

Verifiable Identity with Digital Certificates

The bedrock of any Zero Trust environment is verifiable identity. PKI provides unique digital ID aka Digital Certificates to users, devices, and applications. Digital Certificates, undergo rigorous verification by trusted authorities, ensuring only authorized personnel enter the digital castle. This granular authentication eliminates impersonation attempts and infiltration based on stolen credentials.

Some of the certificate types which could be used are:

Client Certificates

Authenticate users accessing web applications, VPNs, secure email, and other network resources. Issued to individuals and stored on their devices or browsers.

TLS/SSL Certificates

Secure web and application traffic, encrypting data in transit and verifying server identity to prevent interception and man-in-the-middle attacks.

Machine Certificates

Authenticate devices like servers, laptops, IoT devices, and network infrastructure. Ensure secure communication and access control for device-to-device and device-to-network interactions.

Code Signing Certificates

Verify the authenticity and integrity of code and software, ensuring it hasn't been tampered with and comes from a trusted source.

Document Signing Certificates

Ensure the authenticity and integrity of digital documents, preventing unauthorized alterations and verifying signer identity.

Email Signing Certificates

Provide cryptographic signatures for emails, validating sender identity and protecting against phishing and spoofing attacks.

Fortifying the Walls: Secure Communication Channels

Beyond verifying identities, PKI builds impenetrable walls around your data. It empowers secure communication channels through encryption, transforming sensitive information into an unreadable cipher for unauthorized eyes. Think of it as a whisper-proof tunnel between trusted domains, ensuring the integrity and confidentiality of every message. Here are some of the encryptions which could be used:


Advanced Encryption Standard is widely used for encrypting large amounts of data in transit and at rest.


Used for key exchange and digital signatures, providing high security for sensitive data.


Elliptic Curve Cryptography is more efficient than RSA for key exchange, offering equivalent security with smaller key sizes.


Diffie-Hellman Key Exchange securely establishes shared encryption keys without directly transmitting them.

By employing these encryptions and security features, PKI builds robust communication channels, transforming your digital fortress into an impenetrable stronghold for sensitive data.

Remember to choose the appropriate encryption algorithms and key sizes based on your security requirements and performance needs.

Layered Security with Multi-Factor Authentication

But PKI’s contribution doesn’t stop there. It seamlessly integrates with multi-factor authentication (MFA), adding another layer of defense. MFA acts as a vigilant sentry, demanding not just a valid passport but also a secret handshake (a one-time code or biometric verification) before granting access. This layered approach significantly reduces the effectiveness of stolen passwords or compromised credentials.

Here are some examples of how PKI contributes to different MFA options:

Smart cards & PIV/CAC Cards:

  • PKI enables smart cards and PIV/CAC cards to store user certificates and private keys securely. These cards act as the “something you have” factor in MFA, requiring physical possession for authentication.

Client Certificates & TLS/SSL Certificates:

  • Client certificates issued by a PKI can be used for client-side TLS authentication, acting as an “something you have” factor for secure VPN access, web logins, and other services.

  • TLS/SSL certificates with server authentication ensure you’re connecting to the intended website and prevent man-in-the-middle attacks, contributing to the “something you know” factor.

Overall, PKI serves as a foundational technology for various MFA solutions, providing secure storage for credentials, verifying identities and certificates, and enabling strong cryptographic mechanisms. By integrating PKI with other MFA methods like passwords, biometrics, or one-time tokens, you can create a highly secure and layered authentication environment.

Standards Relating to Zero Trust and PKI

While there isn’t a single unified standard specifically devoted to Zero Trust with PKI, several existing standards address various aspects relevant to their integration:

  • NIST SP 800-207: Zero Trust Architecture: This publication from the National Institute of Standards and Technology (NIST) defines the principles and components of a Zero Trust architecture. Notably, it emphasizes the importance of identity and access management (IAM) as a foundation for Zero Trust, highlighting the role of PKI in establishing strong identity verification and granting least-privilege access.
  • NIST SP 800-53B: Security and Privacy Controls for Federal Information Systems and Organizations (FISCAM): This publication provides a catalog of security and privacy controls, including several relevant to PKI in the context of Zero Trust. These controls address aspects like certificate management, authentication mechanisms, and secure communication channels.
  • IETF RFC 8492: JSON Web Signature (JWS): This standard defines a compact and widely-used format for representing digital signatures electronically. JWS allows incorporating PKI signatures into various data formats, facilitating secure data exchange in Zero Trust environments.
  • IETF RFC 6978: OAuth 2.0: Bearer Token Usage: This standard specifies the OAuth 2.0 framework for authorization, a critical component of Zero Trust access control. PKI can be used for secure token signing and verification within OAuth workflows, enhancing the overall security posture.
  • FIDO2 Specifications: The Fast Identity Online (FIDO) Alliance develops standards for strong authentication, including FIDO2. It enables password-less authentication using cryptographic keys (such as those used in PKI), aligning with Zero Trust principles of eliminating reliance on weak passwords.
  • OpenID Connect (OIDC): This framework builds upon OAuth 2.0, providing standardized mechanisms for sharing user identity information between applications. Integrating PKI within OIDC can strengthen authentication and authorization workflows within Zero Trust environments.
  • Cloud Security Alliance (CSA) Controls: The CSA, a global nonprofit organization, provides control frameworks for cloud security. Their CCM (Certificate and Key Management) framework addresses PKI security best practices, which are crucial for implementing Zero Trust principles in cloud-based environments.
  • ISO/IEC 27001: Information Security Management Systems (ISMS): This international standard sets out requirements for establishing, implementing, maintaining, and continually improving an Information Security Management System (ISMS). While not explicitly mentioning Zero Trust, the ISMS principles of confidentiality, integrity, and availability align with Zero Trust goals, and PKI plays a vital role in achieving these goals.

It’s important to remember that these standards are not an exhaustive list and should be considered as building blocks within your Zero Trust implementation. Choosing appropriate standards to leverage and effectively integrating them with your PKI infrastructure is key to achieving a robust and secure Zero Trust architecture.

Vigilance Remains Key 

Having said, PKI is not a magical shield. Its effectiveness relies on meticulous management. Certificates need constant vigilance, vulnerabilities must be patched promptly, and threats must be monitored relentlessly. Neglecting these aspects could leave even the most secure PKI fortress vulnerable.

PKI is not just a relic of the past; it’s a critical architect in the construction of a Zero Trust future. Its ability to establish digital trust, build secure communication channels, and enable granular access control makes it an invaluable tool for organizations navigating the ever-evolving threat landscape. While vigilance and comprehensive security practices remain paramount, PKI provides the trustworthy foundation upon which a truly secure Zero Trust castle can be built, ensuring your digital kingdom remains safe from even the most cunning invaders.

Codegic & Zero Trust

Codegic empowers Zero Trust security through its comprehensive PKI solutions. With powerful CA, OCSP (Online Certificate Status Protocol) verification and robust Registration Authority (RA) capabilities, Codegic builds a bedrock of verifiable identities for users, devices, and applications. This foundation enables strong authentication, secure communication channels, and simplified access control – key pillars of Zero Trust architecture. Whether securing sensitive internal data or collaborating with trusted partners worldwide, Codegic’s PKI solutions bridge the gap, offering seamless, frictionless security without compromising agility or innovation.

Choose Codegic and build your impregnable digital fortress, brick by verified brick.


What role does PKI play in implementing Zero Trust, and how does it contribute within this framework?

Public Key Infrastructure (PKI) plays a pivotal role in implementing Zero Trust by providing the foundation for establishing verifiable identity and secure communication channels. PKI issues digital certificates, which undergo rigorous verification by trusted authorities, ensuring only authorized personnel gain access to digital resources. These certificates authenticate users, devices, and applications, eliminating impersonation attempts and preventing infiltration based on stolen credentials. Additionally, PKI enables encryption protocols like AES, RSA, ECC, and DHKE, which fortify communication channels, transforming sensitive information into unreadable ciphers for unauthorized access.

Can you provide examples of how PKI enhances security against threats like stolen passwords or compromised credentials?

PKI seamlessly integrates with multi-factor authentication (MFA) methods within a Zero Trust environment, adding an extra layer of defense against credential-based threats. For instance, PKI enables the use of smart cards and PIV/CAC cards as physical authentication factors, in addition to traditional password-based authentication. Client certificates and TLS/SSL certificates issued by PKI serve as “something you have” factors for secure VPN access and web logins, complementing other MFA methods such as biometrics or one-time tokens. This layered approach significantly reduces the effectiveness of stolen passwords or compromised credentials, enhancing the overall security posture within a Zero Trust architecture.

What are some common challenges faced when using Online Certificate Status Protocol (OCSP)?

To learn about OCSP challenges, checkout our article on 7 OCSP Challenges.

Where can I get more info about PKI?

To learn about PKI checkout our article on PKI Basics.