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What is Public Key Infrastructure (PKI)?

Public Key Infrastructure is a system designed to manage the creation, distribution, identification, and revocation of public keys.

PKI is one of those topics in the world of cryptography that often leaves people confused. However, understanding it properly is imperative if you want to ensure completely secure communication for any purpose. Therefore, in this article, we’re going to take a look at every important aspect of PKI that anyone should know about it. Let’s get started:

What is Public Key Infrastructure (PKI)?

Public Key Infrastructure (PKI) is a system designed to manage the creation, distribution, identification, and revocation of public keys. The system consists of a set of entrusted user roles, policies, procedures, hardware and software.

The core idea behind this system is to ensure that a public key is used only by its owner and no one else. Information can be encrypted and securely transmitted even without PKI, but in that case, there won’t be any method to ensure the identity of the sender.

The Need of PKI (Public Key Infrastructure)

It’s important to understand that the role of encryption is to ensure secure transfer of data from one end to another end. On one end someone encrypts a message using a public key, and someone else on the other end decrypts that message using his private key.

Only two people having the pair of corresponding private and public keys can see the message, and no one else can see it by intercepting the data packets in midair.

However, while encryption allows secure transfer of data from one end to another end, it doesn’t guarantee that the public key was used by the actual owner of that key. The key may be obtained by someone else (which often happens with public keys because of their public” nature), who may then use it to send some encrypted but misleading information.

The problem is multiplied when the public key is to be used by a group of people instead of just one person. More numbers of people mean more risk of keys falling into hands of a third-party. Plus, in this age of automation keys are not exclusive to humans alone – they’re allotted to some automated computers as well. And computers, as you know, get hacked.

Depending on the sensitivity of the information to be shared there must be some way to establish the identity of a person who owns a public key. And that is where PKI steps in.

PKI binds each public key with identity of its owner with help of a digital SSL certificate. This process of binding may be completely automated or depending on the preferences of parties involved, completed under human supervision. Once a public key has been bounded with a digital certificate, the certificate can act as a secondary measure to establish the identity of the public key owner.

Components of PKI

A Public Key Infrastructure implementation typically consists of following 4 elements:

  • A Certificate Authority (CA), which acts as “the root of trust”. The CA issues digital certificates representing the ownership of a public key.
  • A Registration Authority (RA), also known sometimes as a subordinate CA, which validates the registration of a digital certificate with a public key. Every time when a request for verification of any digital certificate is made, it goes to RA. The RA then decides whether to authenticate the request or not. RA can also issue certificates for specific use cases depending on the permissions granted to it by CA.
  • A certificate database, which issues and revokes certificates.
  • And finally, a certificate store where issued certificates are stored with their private keys.

Applications and Use Cases of PKI

PKI is used in a number of different ways. It’s used in smart card logins, encryption of XML documents, secure email messaging and client system authentications. In all those cases where data security is of paramount importance, PKI is used. It’s also used in the Internet of Things (IoT) to ensure secure communication between two trusted devices. Some of the sectors where it’s used heavily include finance, healthcare, governments, and military. Management of enterprise-class databases is another area where PKI can be seen in action.


If you want to ensure completely secure transfer of data, PKI is a must. Whether you want secure communication for your organization, for IoT devices, for your personal emails, for secure data transfer or for any other purpose, PKI is the way to get complete security with an assurance of identity. Of course, other methods exist (i.e. web of trust), but they’re not scalable enough for large communities. And that’s what differentiates PKI – it’s reliable and scalable both at the same time.

Hopefully, we could explain this subject to you in an easy manner. Keep checking back for more security related stuff.

About the Author

Nikita Gupta

Nikita Gupta is a seasoned professional with a master's degree in Computer Applications. She brings over 10 years of profound experience to the realm of technology. Her exceptional expertise spans software security, data security, and mastery in SSL/TLS. When it comes to cutting-edge solutions for securing digital assets, Nikita is a dedicated pro.