Certified: The Security+ Prepcast

In this episode, we are introducing the foundational concept of cryptography and the structure that supports it—Public Key Infrastructure. These topics are essential to understanding how cybersecurity professionals protect data, verify identities, and prevent attackers from tampering with or forging sensitive information. Cryptography is not just a technical buzzword—it is the engine behind secure communications, encrypted storage, and trusted digital interactions.
Let’s begin with the fundamentals of cryptography. At its core, cryptography is the science of transforming data to keep it secure. It allows us to protect confidentiality by hiding the contents of a message. It also preserves integrity by ensuring that data has not been changed. And it supports non-repudiation by proving that a specific user performed a specific action.
Confidentiality means making sure that only authorized people can read the information. Integrity means that the message has not been altered in transit or storage. Non-repudiation ensures that the sender of a message cannot later deny sending it. These three goals—confidentiality, integrity, and non-repudiation—are often supported by the same cryptographic tools, working together in carefully planned combinations.
Cryptographic principles include encryption, hashing, and digital signatures. Encryption converts plain text into cipher text using a key. Only someone with the correct key can decrypt it. Hashing transforms data into a unique string that represents the content. If the content changes, the hash changes too. Digital signatures combine both encryption and hashing to verify the sender and the content at the same time.
Use cases for cryptography are everywhere. Email encryption protects sensitive messages from being read by unauthorized parties. Secure web browsing relies on encrypted sessions to prevent eavesdropping. Digital signatures are used in legal agreements, financial transactions, and software updates to verify authenticity. Even password storage uses cryptographic hashing to ensure that stored credentials cannot be easily stolen and reused.
Real-world scenarios make these concepts easier to understand. For example, when you visit a secure website, your browser uses cryptography to establish an encrypted connection. This means that everything you do on that site—whether shopping, banking, or filling out forms—is hidden from attackers. Another example comes from health care. When a patient’s medical record is sent from one provider to another, encryption ensures that private data remains secure throughout the transmission process.
Now let’s shift to Public Key Infrastructure, often abbreviated as P K I. This system provides a framework for managing keys and digital certificates. It allows organizations to issue, distribute, and validate secure identities across networks. P K I relies on a pair of keys—a public key and a private key—that work together to encrypt and decrypt data.
The public key can be shared freely. Anyone can use it to encrypt a message intended for the owner of the private key. The private key is kept secret and is used to decrypt messages or to create digital signatures. This two-key system is called asymmetric encryption and is the foundation of most secure communications on the internet.
One of the most important functions of P K I is establishing trusted identities. When you visit a secure website, your browser checks the site’s digital certificate to make sure it is valid. That certificate proves that the website is who it claims to be and not an impostor. These certificates are issued by trusted certificate authorities that verify the identity of the requester before issuing the certificate.
This chain of trust is what allows P K I to scale globally. From securing websites to authenticating software, it ensures that digital interactions can be trusted. Without P K I, it would be far easier for attackers to impersonate others, trick users, or tamper with messages and data.
Key escrow is another concept within P K I. It refers to the practice of storing a backup copy of a cryptographic key with a trusted third party. This can be useful for recovering encrypted data if a key is lost or an employee leaves the organization. The advantage of key escrow is that it provides a safety net for critical data access. Without it, encrypted information could be lost forever if the private key is destroyed.
However, key escrow also introduces risks. If the escrowed keys are not protected properly, they can be stolen or misused. This would give attackers the ability to decrypt sensitive information or impersonate the key owner. For this reason, organizations must carefully consider how and where they store escrowed keys—and who has access to them. Secure storage, strong access controls, and auditing are all part of a responsible key escrow strategy.
For the Security Plus exam, make sure you understand the basic goals of cryptography—confidentiality, integrity, and non-repudiation. Be able to identify when and why encryption, hashing, and digital signatures are used. Understand how public and private keys work together and the role of certificate authorities in building trust. Also, know the benefits and risks of key escrow. You may be asked to select the best cryptographic solution for a scenario or identify the purpose of a P K I component like a certificate or key pair.