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Understanding Public Key Infrastructure: Overview and Key Concepts

Understanding Public Key Infrastructure: Overview and Key Concepts

In the digital sphere, everything has an identity. At a basic level, a digital identity is defined as an IP address or other identifying digital data such as a name or email address, but digital identities are contained within organizations, individuals, and devices.

A digital identity is as unique as a fingerprint and as personal as an individual’s social security information, and as such, it is imperative that it remains private and protected. Public Key Infrastructure (PKI) plays a pivotal role in securing digital identities, but is an extremely broad subject, with many different solutions, use cases and practices. So when approaching PKI security infrastructure it is difficult to know where to begin or what the best practices are for implementation.

This blog will cover the key concepts and components of PKI, as well as the benefits, applications and best practices of PKI Management, and how it fits into your business security posture.

What is Public Key Infrastructure (PKI)?

Public Key Infrastructure (PKI) is the cryptographic system in which all digital certificates are founded. Through encryption, using a combination of public and private keys, PKI creates a secure environment for the transfer of data and ensuring trust between the sender and the recipient.

PKI is essential for providing trust and security throughout industries, organizations and governments by protecting the privacy and ensuring the authenticity of organizational data, communications and digital identities.

PKI secures data and creates trust in the form of digital certificates, which are issued by Certificate Authorities (CAs) to organizations after creating a Certificate Signing Request (CSRs). Once a CSR has been approved and a certificate has been issued, an organization or entity can authenticate and protect their communications, web domains, or documents provided that it is the correct certificate and within its validity period.

How PKI Works: Key Concepts and Processes

How is Data Encrypted with PKI?

The function of PKI is to secure data through encryption upon transfer. In a nutshell, two or more correspondents exchanging data will possess both a public and private key. Correspondent A will send encrypted data using a hash algorithm and their private key. Correspondent B can decrypt the algorithm with their corresponding public key.


In transferring the data, the key pair has two functions:

  • Verifying the identity of Correspondent A with their unique key pair so that Correspondent B can be certain of the sender’s authenticity
  • Securing the data in transfer so that only the recipient with the corresponding public key can access the data

During this process a digital certificate will verify that the public and private keys belong to the correct recipient and sender respectively.

How are Digital Certificates Created?

Through PKI, organizations can request digital certificates, which are issued by CAs. A digital certificate demonstrates authenticity of an entity, such as an organization, individual user or a server. When an organization generates a CSR, it is sent on to the Registration Authority (RA) who will verify the identity of the organization or user through vetting procedures and confirm this to the CA who will then issue the certificate. Some CA’s, such as GlobalSign, will have their own vetting procedures internally.

Components of PKI

It is important to understand the basic components involved when implementing PKI into security infrastructure. While PKI facilitates the provisioning, renewal and revocation of digital certificates, they are issued by a CA.

The role of a CA is to develop and maintain a chain of trust so that organizations can ensure that their certificates are secure. Within this chain of trust, there are two different types of CAs; a Root Certificate Authority and an Intermediate Certificate Authority. 

Trust is also established through certificate inventory management and can be maintained in two ways:

  • Certificate Revocation List (CRL):  is an inventory of certificates that have been revoked by a CA before their expiration date. This is often caused by issues such as private key compromise. For example, a browser requests a list of revoked certificates for a HTTPS enabled webpage to the issuing CA, who will then return a list of revoked and on-hold certificates.
  • Online Certificate Status Protocol (OCSP): An Online Certificate Status Protocol can provide similar information to a CRL, but the request is instead sent to an OCSP server, meaning that the requested information can be returned at a quicker rate and in greater depth. An OCSP responder will then detail the certificate status, which will include one of three responses: Good (valid for use), Revoked (temporarily or permanently) and Unknown (not recognized by the responder).

A collaborative effort to maintain trust online, through a chain of trust between CAs and browsers, as well through proper certificate management through CAs, is what makes the use of PKI such a strong solution for reinforcing security infrastructure.

Benefits of PKI

PKI is a powerful tool for enterprises to use to strengthen their security posture, and provides organizations with a comprehensive solution for enhancing data security and operational efficiency. Here are the 6 key benefits of PKI:

  1. Authentication mitigates the risks of identity fraud, data breaches, and unauthorized access
  2. Provides enhanced data security by maintaining the confidentiality, integrity, and authenticity of data across a wide range of applications and environments
  3. Offers greater efficiency with improved management processes
  4. Streamlined access control ensures permission is only given to trusted entities to gain access
  5. Offers greater scalability for a diverse range of business security needs
  6. Integrating PKI offers low-cost security as enterprises could save on the cost of fines, legal fees, and business losses that can come from security breaches or mismanagement

Learn more about the benefits of PKI for business security

Applications of PKI

There are numerous industries that depend on the application of PKI for their security structure, including finance, legal, healthcare, e-commerce, supply chain management and government, all with varying applications for each. Some examples include:

Best Practices for Implementing PKI

Organizations and IT teams need to take serious considerations when implementing PKI into their security posture to overcome the challenges faced. These challenges can be addressed with proper planning:

  • Proper key management: Managing cryptographic keys properly is essential when planning to place PKI at the center of your security infrastructure. Managed PKI helps to eliminate the risk of human error and cuts down on resources used when managing certificates. Integrating PKI Management solutions into your certificate pipeline facilitates centralized control and visibility for all types of certificates as well as automated certificate provisioning through the use of APIs, saving time and overall cost.
  • Regular security audits: Conducting regular audits is necessary for developing a strong PKI security posture. Initially these will assist in assessing organizational security needs, including security training, certificate needs, access management and mitigation of potential risks. Going forward these must be performed routinely to inform changing needs within the business, by keeping updated on evolving threats and gaps within security infrastructure, business and industry requirements and compliance maintenance.
  • Partnering with a trusted Certificate Authority: When implementing PKI, it is important to take the time to consider what the business needs from a CA. A potential CA should be reputable, demonstrating trust, integrity and security. This should include the performance of rigorous vetting procedures and the maintenance of industry standards.

Final Thoughts

The key to PKI lies in the distribution of security among each of its components throughout its implementation, such as its foundation in asymmetric cryptography, which utilizes both public and private keys. In managing PKI and certificate lifecycles, there are also multiple players who ensure that trust is maintained for browsers and end users. Through distributing the responsibility of maintaining trust, PKI creates a strong foundation for security.

Managed PKI can create a centralized inventory of certificates, audit potential security threats and manage certificate renewal, simplifying the process of PKI management and reducing the risk of compromise.

PKI is a powerful solution for providing strong security infrastructure within an organization and protecting digital identity. However implementing PKI is not without its challenges, as organizations themselves must ensure proper key and certificate management to maintain security founded on a Public Key Infrastructure. While this can put pressure on company resources and can still result in human error or a breach, these risks can be mitigated through the use of CA solutions and automation.


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