What is the role of public key infrastructure (PKI) in email security?

The role of public key infrastructure (PKI) in email security primarily revolves around enabling secure communications through mechanisms that authenticate the sender's identity and ensure the confidentiality of the message.

In a secure email context, PKI provides the framework for creating, distributing, and managing digital certificates and public-private key pairs. When a sender encrypts an email with the recipient's public key, only the recipient can decrypt it using their corresponding private key, ensuring that the content remains confidential during transmission. Additionally, digital signatures created with the sender's private key allow recipients to verify the authenticity of the sender and ensure that the message has not been altered in transit.

By using PKI, organizations can thus establish a trust framework that supports secure email practices such as Secure/Multipurpose Internet Mail Extensions (S/MIME). This significantly enhances the security of email communications, protecting sensitive data and preventing impersonation attacks.