TechKnowSurge
CompTIA Security+ 1.4 ISC2 CISSP 3.6 CompTIA SecurityX 2.3 NIST 800-53 SC-13 Cisco CCNA 5.5 CompTIA Network+ 4.1 CompTIA Security+ 3.1 ISC2 CISSP 4.3
TechKnowSurge Catalog Videos Applied Cryptography
VideoSecurityFree

Applied Cryptography

Cryptographic tools like hashing, symmetric and asymmetric encryption, and public key infrastructure are applied in combination across real-world protocols and technologies to establish secure communications. This content covers how those building blocks come together in TLS, VPN tunnels, and other widely used security protocols.

⚑ Complete this video to capture a CTF flag worth 1 point.

About this video

Cryptographic building blocks — including hashing algorithms, symmetric ciphers, asymmetric encryption, and key exchange mechanisms — are rarely used in isolation. In practice, they are selected and combined based on the specific security problem at hand, then formalized into protocols that can be deployed across networks and systems. Public key infrastructure, for example, draws on hashing and asymmetric encryption together to create digital certificates that verify the identity of websites and services. Transport Layer Security extends that model further, using all major classes of cryptographic algorithms to establish encrypted, authenticated communication channels, most visibly in HTTPS. VPN technology demonstrates how the same principles are adapted for different network-layer requirements. A TLS-based VPN tunnel functions similarly to a secure website connection and operates at the application layer, while an IPsec VPN tunnel operates at Layer 3, encrypting traffic at the IP packet level. IPsec remains the more prevalent approach for site-to-site connectivity, where organizations need to link separate physical locations across potentially untrusted networks. Both approaches rely on the same underlying cryptographic concepts — hashing, symmetric algorithms, and asymmetric algorithms — but implement them differently depending on where in the network stack the security needs to be enforced. This pattern of composing ciphers and algorithms into protocols, and then reusing those protocols within larger frameworks, is consistent across the entire landscape of modern security technology. Wireless security standards, authentication systems, and communication protocols all follow the same design logic: identify the vulnerability, select the appropriate cryptographic mechanism, build a protocol around it, and integrate that protocol into the broader technology stack. Understanding how these layers connect is foundational to implementing and evaluating real-world cryptographic security solutions.

What you'll learn

What's covered

Applying Cryptographic Solutions

Aligned to

CompTIA Security+
1.4 Explain the importance of using appropriate cryptographic solutions.
3.1 Compare and contrast security implications of different architecture models.
ISC2 CISSP
3.6 Select and determine cryptographic solutions.
4.3 Implement secure communication channels according to design.
CompTIA SecurityX
2.3 Given a scenario, implement appropriate cryptographic protocols and algorithms.
NIST 800-53
SC-13 Cryptographic Protection.
Cisco CCNA
5.5 Describe IPsec remote access and site-to-site VPNs.
CompTIA Network+
4.1 Explain the importance of basic network security concepts.

Key terms

Hash Function
A mathematical algorithm that converts input data of any size into a fixed-size output value used to verify data integrity.
Symmetric Encryption
An encryption method that uses the same key for both encryption and decryption.
Asymmetric Encryption
An encryption method that uses a public key to encrypt data and a private key to decrypt it.
Public Key Infrastructure
PKI
A framework of hardware, software, policies, and standards used to create, manage, and distribute digital certificates.
Transport Layer Security
TLS
A cryptographic protocol that provides secure communication over a network, successor to SSL.
IPsec
A suite of protocols that authenticates and encrypts IP packets to provide secure communication over a network.
Virtual Private Network
VPN
A technology that creates a secure, encrypted tunnel over a public network to protect data in transit.
Key Exchange
A method used to securely share cryptographic keys between parties over an insecure channel.
Digital Certificate
An electronic document that uses a digital signature to bind a public key with an identity.
Encapsulation
The process of wrapping data with protocol headers as it passes down the layers of the OSI model.
Network Layer
Layer 3 of the OSI model, responsible for logical addressing and routing data packets between networks.
TLS VPN
A VPN tunnel that operates at the application layer using the TLS protocol to encrypt traffic, commonly used for remote user access via a web browser.

Topics

Cryptography Tls Ipsec Vpn Public Key Infrastructure Symmetric Encryption Hashing

Transcript

There's a lot of different cryptography solutions out there. Things like hashing, where we can hash things and create that unique fingerprint, and this is just a small list, there's a ton that are available out there. We have the encryption side of things where we can encrypt and decrypt, and we have symmetric encryption algorithms and asymmetric encryption algorithms. Although some of it's a little misleading, because Diffie-Hellman is asymmetric cryptography but technically it's not actually encryption, it's just key exchange.

Applying Cryptographic Solutions

Then we take these cryptographic solutions and apply them to some sort of issue that we see. For instance, the public key infrastructure has been implemented so that we can securely connect to sites and have some sort of verification of those sites. What do we use in it? We use those hashes, so we can hash the information and create that unique fingerprint, and then we take those and we encrypt it with asymmetric cryptography, so RSA would be an example of that, that we encrypt this information then to create these digital certificates.

We can also take these cryptographic solutions and apply them to older protocols to make them more secure. As an example, HTTP is an old protocol that is secure, and so what do we do? We create transport layer security, which we can add to protocols like HTTP to make it more secure, so now we have HTTPS. Transport layer security uses hashing algorithms, it uses symmetric algorithms, it uses asymmetric algorithms, and it uses public key infrastructure, or some sort of combination of those things, to create this secure communication.

VPN Tunnels

Transport layer security can be used to secure our communication and it's used in a lot of different situations, but one of them is connecting to websites. However, that's not the only scenario that we have out there. There are times when we have a company network and we want to interconnect different sites.

In this example right here, let's say we have a site A and a site B and we want to create a tunnel between them. A tunnel means that we're going across other networks, but we want it to be directly connected between these two different sites, and so we create a tunnel between these sites. The problem is that it's going across maybe insecure networks and we need to encrypt that. So then we create a VPN tunnel. A VPN stands for virtual private network, and so it's virtually private because we encrypt that traffic going across those insecure networks.

A VPN tunnel could be set up using two different protocols. It could be an IPsec VPN tunnel or a TLS VPN tunnel, and those are two different things. The TLS VPN tunnel would operate much like a website, which has a lot of advantages to it, but it has some drawbacks and disadvantages. So maybe we want to create an IPsec tunnel, which is actually much more prevalent out there when it comes to VPNs.

Really, what that looks like is a TLS happens at the application layer, versus an IPsec happens at layer three, at an IP packet layer. So it operates quite a bit differently, although it uses a lot of the same concepts. It has the hashes and the symmetric algorithms and the asymmetric algorithms, and it uses variations of those as well, to implement an IPsec VPN tunnel.

Other Protocols and Use Cases

There are a lot of other protocols and use cases. We have some sort of issue that we're trying to solve, we choose the specific cipher or algorithm that we need to use and apply it and create a protocol out of it, and from that protocol we could even use that protocol within other protocols. So we see here some communication protocols, wireless protocols, authentication protocols. An example might be that we use RC4 cipher in TKIP, and then we take TKIP and reuse that in WEP and WPA. And so we will take and make these different protocols out of these different ciphers that we have.

About TechKnowSurge

TechKnowSurge builds IT and cybersecurity professionals through hands-on, concept-first training built around real understanding — not memorization. Free interactive tools, structured programs, and 25+ years of real-world experience, all in one place.

Explore free tools and programs →