Understanding the Cryptography Behind PKI

Understanding the Cryptography Behind PKI

Public key infrastructure, or PKI, is a system for uniquely identifying individuals and devices using digital certificates. PKI uses a combination of asymmetric and symmetric key cryptography to ensure that only authorized individuals can access sensitive information. In this blog post, we’ll take a closer look at the cryptography behind PKI and how it works to keep your data secure.

Asymmetric Key Cryptography

PKI relies on asymmetric key cryptography, also known as public key cryptography, to generate digital certificates. Asymmetric encryption uses a pair of mathematically-related keys to encrypt and decrypt data. One of the keys is kept private, while the other is made available to anyone who needs to verify the identity of the owner of the private key.

In PKI, the private key is used to sign digital certificates, while the public key is used to verify those signatures. This ensures that only the private key owner can create a valid certificate and that anyone can confirm that a given certificate is genuine. However, it’s important to note that neither the private nor public keys can be used to derive the other; they are entirely unrelated.

Symmetric Key Cryptography

In addition to asymmetric key cryptography, PKI also uses symmetric key cryptography. Symmetric key cryptography is a type of encryption that uses a single shared key to encrypt and decrypt data. In contrast to asymmetric key cryptography, symmetric key algorithms are much faster and more efficient. However, they also have some significant drawbacks.

The biggest drawback of symmetric key algorithms is that they require both parties to share the same secret key ahead of time. This can be difficult to do in practice, mainly when those parties are located in different parts of the world. Additionally, if the secret key is compromised, all data encrypted with that key is also compromised. For these reasons, symmetric key algorithms are typically only used to encrypt small amounts of data, such as session keys or messages.

PKI in Practice

Now that we’ve seen how PKI uses both asymmetric and symmetric key algorithms, let’s look at how these concepts come together in practice. When an individual or device needs to be identified using PKI, a digital certificate is generated using their public/private key pair. This certificate contains information about the individual or device being placed and their public key.

When another party needs to verify the identity of the individual or device associated with a given certificate, they use the public key included in the certificate to decrypt it. If they can successfully solve the certificate, they know that it was created by someone who possesses the corresponding private key—and thus, the individual or device associated with that certificate is who they claim to be.

Getting Started With PKI

If you’re looking to get started with PKI, there are a few things you’ll need to do. First, you’ll need to generate a public/private key pair for each individual or device that will be using the system. You can use any tools to do this, such as Keyfactor. 

Once you have a public/private key pair for each entity using the system, you’ll need to generate digital certificates for them. These certificates can be generated using the same tools you used to generate the key pairs. Once you have a certificate for each entity, you’ll need to ensure that they are correctly signed and that the signature can be verified using the entity’s public key.

Finally, you’ll need to place a system for distributing certificates and keys. This system will need to be secure, as it will be responsible for transmitting sensitive information.


PKI is a critical component of internet security; it allows us to verify identities and ensure that data stays confidential. In this blog post, we’ve taken a closer look at how PKI works and explored the role that both asymmetric and symmetric essential cryptography play in making it possible. By understanding how PKI works at a cryptographic level, we can better appreciate how important it is to keep our data safe from unauthorized access.

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About the Author: Barry Lachey

Barry Lachey is a Professional Editor at Zobuz. Previously He has also worked for Moxly Sports and Network Resources "Joe Joe." he is a graduate of the Kings College at the University of Thames Valley London. You can reach Barry via email or by phone.