Certified: The CISSP Prepcast

Welcome to The Bare Metal Cyber CISSP Prepcast. This series helps you prepare for the ISC squared CISSP exam with focused explanations and practical context.
In this episode, we’ll explore fundamental Cryptographic Concepts with a focus on Symmetric and Asymmetric encryption. These two cryptographic approaches form the foundation of modern information security. They are used every day to protect sensitive data, secure communication channels, verify identities, and establish trust across digital systems. Understanding how they work, where they differ, and how to apply them effectively is essential for any cybersecurity professional—and a core expectation for the CISSP exam.
Cryptography is the science of protecting information by transforming it into a form that cannot be read or modified without the correct key. It safeguards digital assets by enforcing four key principles: confidentiality, integrity, authentication, and non-repudiation.
Confidentiality ensures that only authorized individuals can access information. Integrity ensures that the information has not been altered or tampered with. Authentication confirms the identity of users and systems. And non-repudiation ensures that once an action has occurred, it cannot be denied by the party who performed it.
To accomplish these goals, cryptography uses a variety of techniques. Encryption converts plain text into cipher text. Hashing produces unique, fixed-length representations of data. Digital signatures validate the origin and integrity of a message. Each of these tools plays a distinct role, but today our primary focus will be on encryption—specifically, how symmetric and asymmetric encryption differ, and how they complement each other in practice.
Let’s begin with symmetric encryption. This method uses a single secret key to both encrypt and decrypt information. The same key must be shared between the sender and the receiver, and both parties must keep that key confidential to maintain security.
Common symmetric encryption algorithms include the Advanced Encryption Standard, also known as A E S, as well as Triple Data Encryption Standard, which is abbreviated as Three D E S, and Blowfish. Among these, Advanced Encryption Standard is widely regarded as the most secure and efficient for current use. It supports key sizes of one hundred twenty-eight, one hundred ninety-two, and two hundred fifty-six bits, and is approved for protecting classified government information in many countries.
The key strength of symmetric encryption lies in its speed. It is fast, efficient, and well suited for encrypting large volumes of data—such as file systems, databases, or network traffic. Because it uses fewer computational resources, symmetric encryption is ideal for environments where performance is critical.
However, symmetric encryption also presents a challenge—key distribution. If both parties need the same key, how do they exchange it securely? Sending the key over an insecure channel could allow attackers to intercept and decrypt the message. Storing it improperly could expose it to insider threats. Key management becomes more complex as the number of participants increases.
To solve this problem, many systems use symmetric encryption for the data itself but rely on asymmetric encryption to securely distribute the symmetric key. This is where asymmetric encryption comes into play.
Asymmetric encryption is also known as public-key cryptography. It uses a pair of mathematically related keys: one public and one private. The public key can be shared openly with anyone, while the private key is kept secret by the owner.
In asymmetric encryption, anything encrypted with the public key can only be decrypted by the corresponding private key—and vice versa. This mechanism provides a secure way to establish communication without needing to pre-share a secret key.
Common asymmetric algorithms include R S A, which stands for Rivest Shamir Adleman, as well as Elliptic Curve Cryptography, often abbreviated as E C C, and Diffie-Hellman key exchange. R S A is widely used for digital signatures and secure key exchange. Elliptic Curve Cryptography offers the same level of security as R S A but with much smaller key sizes, making it more efficient for mobile devices and embedded systems. Diffie-Hellman is used to establish a shared secret over an insecure channel.
One of the key advantages of asymmetric encryption is that it supports digital signatures and non-repudiation. A digital signature is created by encrypting a hash of a message with the sender’s private key. Anyone with the sender’s public key can verify the signature, ensuring that the message came from the expected sender and was not altered.
Asymmetric encryption also solves the key distribution problem. Instead of sharing a secret key, each participant generates a key pair. When one party wants to send a secure message, they encrypt it with the recipient’s public key. Only the recipient, who holds the private key, can decrypt it.
However, asymmetric encryption is slower and more computationally intensive than symmetric encryption. That’s why many systems combine the two. For example, a secure website might use asymmetric encryption during the initial handshake to exchange a symmetric session key, then switch to symmetric encryption for the remainder of the session to maximize performance.
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Now let’s talk about how organizations implement effective cryptographic controls. The first step is establishing clear cryptographic policies. These policies define which algorithms and key lengths are permitted, how keys are generated and distributed, how long they are valid, and how they must be stored or destroyed.
Key management is central to cryptographic security. Without strong key management, even the best encryption algorithm can be defeated. Secure generation ensures that keys are created with sufficient randomness. Secure distribution ensures that keys reach their destination without interception. Secure storage involves protecting keys with access controls and possibly hardware security modules. Secure rotation means keys are replaced regularly to minimize exposure. And secure disposal ensures that old keys are destroyed properly when no longer needed.
Cryptographic assessments and reviews are necessary to ensure that the organization is using secure, approved algorithms. Algorithms that were considered secure a decade ago—such as single D E S or M D Five—may now be broken or deprecated. Organizations must stay informed of cryptographic research and regulatory guidance to know when to upgrade or retire their cryptographic systems.
Combining symmetric and asymmetric encryption in security architectures provides both performance and flexibility. For example, in a virtual private network, asymmetric encryption may be used for initial authentication and key exchange, while symmetric encryption is used to secure the data flow. In email systems, public-key infrastructure can be used to verify the sender’s identity, while message content is encrypted symmetrically for speed.
Training is also critical. Technical staff must understand when to use each type of encryption, how to configure cryptographic modules correctly, and how to manage keys securely. Mistakes such as hardcoding keys in applications, reusing keys across systems, or disabling certificate validation can undermine all the benefits of encryption.
Let’s now focus on continuous improvement in cryptographic management. This begins with regular policy reviews. As technology evolves, older algorithms and practices become obsolete. Key lengths that were once considered strong may no longer be sufficient. For example, as quantum computing advances, certain asymmetric algorithms may become vulnerable to new forms of attack.
Organizations must assess these risks and adjust accordingly. This includes migrating to post-quantum cryptography when standards mature, or moving from R S A to Elliptic Curve Cryptography to reduce key size and processing time.
Security assessments, penetration tests, and audits often reveal weak cryptographic implementations—such as expired certificates, unencrypted traffic, or outdated encryption modules. These findings should be used to guide improvements in architecture and operations.
Cross-functional collaboration also strengthens cryptographic management. Security teams work with application developers to ensure proper integration. Legal and compliance teams verify alignment with regulatory frameworks such as GDPR or HIPAA. Operations teams manage certificate lifecycles and monitor for anomalies.
Training must be ongoing. New tools, libraries, and threats require updated knowledge. Developers, administrators, and analysts should regularly attend workshops, review secure coding guidelines, and practice cryptographic troubleshooting.
Finally, proactive strategies ensure resilience. These include testing for certificate pinning, implementing certificate transparency logs, validating proper key usage in cloud services, and simulating cryptographic failures in a safe environment. The goal is not just to use cryptography, but to use it intelligently, reliably, and in a way that supports long-term organizational security.
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