Each time I send a message, upload a file, or shop online, my data moves through many systems. These systems may be secure—or not. That’s why I need a way to protect the content of my messages from prying eyes. Enter encryption. In this article, I explain what is encryption, how it works, why it’s vital for IT security, and what types of encryption exist. I cover everything from simple concepts to real-world techniques. I’ll also show the difference between link and end-to-end encryption, and I explain how modern systems use keys and algorithms to keep your data safe.
Let’s explore the powerful world of encryption—one of the core building blocks of digital trust.
Why Encryption Matters for IT Security
In a digital world full of risks, encryption is my defense. Hackers want my data. Governments want to monitor. Companies want to analyze. I need a way to keep control—and encryption gives me that power.
IT security without encryption would be weak. Every email, password, or photo would be easy to read. That’s why I use encryption every day—often without even noticing it. Secure websites (with HTTPS), messaging apps, banking systems, and cloud storage all rely on it.
Moreover, data on the move is vulnerable. Messages pass through multiple routers, servers, and networks. At every stop, there’s a risk. Encryption solves this. It protects my content, even when others can see the package.
Thanks to encryption, I can trust the systems I use—even when I don’t trust the network in between.
What Is Encryption? Explained Simply
So, what is encryption really? It’s the process of turning readable content (plain text) into scrambled nonsense (cipher text). Only someone with the right key can turn it back.
Encryption uses a mathematical algorithm combined with a key. The algorithm tells the system how to transform the data. The key is a special value that controls the transformation.
Let’s break it down:
- Plain text: The original, readable message
- Cipher text: The unreadable, scrambled version
- Key: A secret that unlocks the cipher text
- Algorithm: The rules used for encrypting and decrypting
The opposite of encryption is decryption. It turns cipher text back into the original plain text using the right key and algorithm.
Importantly, good encryption makes sure that:
- You can’t understand the cipher text without the key.
- Even with lots of resources, breaking the encryption takes too long to be practical.
- The difficulty increases as key length grows (exponentially, in fact).
Even powerful organizations can’t crack strong encryption in a reasonable time—if the system is set up well.
How Encryption Algorithms Work
Encryption isn’t random—it follows rules. These rules (algorithms) use operations to hide the message. There are two main operations in encryption:
Substitution
Each symbol or group in the plain text is replaced with something else. For example, A becomes D, B becomes E, and so on. It’s like a secret alphabet.
Mathematically, this is a bijective function. The input and output sets may differ (like Morse code). But in most computer systems, they’re identical.
Example: Shift all letters forward by one (A→B, B→C).
Transposition
Instead of changing the letters, I just shuffle their order.
Example: Write the message backward.
On their own, these methods are easy to break. But if I combine substitution and transposition, I get strong protection. That’s what modern algorithms do.
Two Models of Encrypting Messages
When I send a message, I have two choices for encryption:
Link Encryption (Line-by-Line)
This method encrypts data between each pair of systems on the path. My computer encrypts for the first server. That server decrypts and re-encrypts for the next, and so on.
Benefits:
- Only two systems at a time need to agree on the key and algorithm.
- It works at low levels of the protocol hierarchy (like network layers).
Downsides:
- Each system must be trusted.
- A single weak link can expose my data.
End-to-End Encryption (E2EE)
Here, I encrypt the message once—for the final recipient. It travels through every system in encrypted form. Only the recipient can decrypt it.
Benefits:
- No one in the middle can read the content.
- I don’t need to trust the path—only the sender and receiver.
Downsides:
- I need a way to exchange encryption keys with every contact.
Because of the stronger security, I always prefer end-to-end encryption. It gives me more control and reduces risk.
How Many Keys Are Used?
The next question is: Do I use the same key to encrypt and decrypt? This gives us two key types:
One Key (Symmetric Encryption)
I use the same key to encrypt and decrypt. This is fast and efficient.
Pros:
- Speed
- Simplicity
Cons:
- I must keep the key secret.
- If someone else gets it, the system breaks.
This is also called Private Key Encryption or Secret Key Encryption.
Two Keys (Asymmetric Encryption)
Here, I use a key pair: one public and one private. The public key encrypts. The private key decrypts.
Pros:
- I can share my public key openly.
- Only I can decrypt messages sent to me.
Cons:
- It’s slower than symmetric encryption.
This system is also called Public Key Encryption. The two keys are mathematically linked. Still, it’s nearly impossible to compute the private key from the public one.
Smart Hybrid Encryption
To get the best of both worlds, I often combine the two methods. This is called hybrid encryption:
- I generate a secret key for symmetric encryption.
- I encrypt this secret key using the receiver’s public key.
- I send both the encrypted key and the encrypted message.
This way, I enjoy the speed of symmetric encryption and the secure key exchange of asymmetric encryption.
How Encryption Processes Plain Text
Plain text isn’t always short. It can be large or unknown in size. So, encryption systems use processing modes. These modes define how the algorithm handles the text.
Block Encryption
I divide the plain text into blocks (usually 64 or 128 bits). Each block is encrypted separately. If the last block is smaller, I pad it to the required size.
Pros:
- Clear structure
- Often more secure
Cons:
- Adds overhead when padding is used
Stream Encryption
Instead of blocks, I encrypt each bit or character as it arrives. The system works like a stream.
Pros:
- No need to pad the message
- Saves bandwidth
- Works in real-time
Cons:
- Without future knowledge, results may be less optimal
Stream encryption is often used in online algorithms, which work step-by-step, without knowing what comes next.
Final Thoughts
Encryption algorithms keeps my data safe. It transforms readable content into protected messages. Whether I use symmetric or asymmetric methods, the goal stays the same: privacy, integrity, and trust.
I now understand what is encryption, how it works, and why it’s critical in IT. It doesn’t just protect big companies—it protects me, every day, in every interaction online.
By using encryption, I take charge of my digital security. I decide who sees my data—and who doesn’t.
So, the next time I click “send,” I’ll smile, knowing encryption has my back.
Credits: Photo by Tima Miroshnichenko from Pexels
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