What is PKI?

Public Key Infrastructure (PKI) is a system that creates, shares, and checks digital “keys” and certificates so computers can talk securely and verify each other’s identity. It uses a pair of keys-one public, one private-to encrypt data and prove who sent it.

Let's break it down

  • Public Key Infrastructure (PKI): a set of tools and rules for handling digital keys and certificates.
  • Public key: a lock-like code anyone can see and use to encrypt a message for you.
  • Private key: the matching key you keep secret; only you can unlock messages encrypted with your public key.
  • Digital certificate: an electronic ID card that ties a public key to a real person or organization.
  • Certificate Authority (CA): a trusted “notary” that issues and signs certificates, confirming they belong to who they claim.

Why does it matter?

PKI lets you trust online interactions-like shopping, banking, or emailing-by ensuring the data you send is private and that the other side is really who they say they are. Without it, anyone could pretend to be a website or intercept your information.

Where is it used?

  • Secure websites (HTTPS) that show the padlock icon in browsers.
  • Encrypted email services that protect messages from being read by others.
  • Virtual Private Networks (VPNs) that create safe connections to remote networks.
  • Software and app signing, which tells users the program hasn’t been tampered with.

Good things about it

  • Provides strong encryption to keep data private.
  • Enables reliable authentication of users, devices, and services.
  • Scalable: works for small businesses up to global enterprises.
  • Supports non-repudiation, meaning a sender cannot deny sending a message.
  • Widely adopted standards make it interoperable across many platforms.

Not-so-good things

  • Setting up and managing PKI can be complex and costly, especially for small organizations.
  • If a Certificate Authority is compromised, trust in all certificates it issued can be broken.
  • Lost or stolen private keys can lead to security breaches unless proper recovery processes exist.
  • Certificate expiration requires regular renewal, which can be administratively burdensome.