What is PKI? The PKI fundamentals

The underpinning concept of PKI, where one person encrypts a message knowing that the recipient has the secret key to decrypt it, has been in practice for thousands of years. Today, it’s most familiar use is probably online communications. To ensure data safety when communicating with others, the data is encrypted and can only be decrypted by a party with the correct private key.

The lockbox has two keys, Left Key (which can only turn to the left) and Right Key (which can only turn to the right). So if the box is in the left-locked position, only the Right Key can open it. And if the box is in the right-locked position, only the Left Key can open it. Bob can make copies of the Left Key and pass them around while keeping the Right Key secret.

When it comes to the internet, the public key is tied or signed by a digital certificate provided by a certificate authority (CA). This means that the CA is, in effect, authenticating that Bob is Bob in the first place. These CAs are trusted third-parties and follow a set of policies and security guidelines that reinforce the faith people place in their certificates.