What is Encryption?

What is Encryption?

Encryption is the practice of transforming readable information (plaintext) into an unintelligible jumble (ciphertext) that only authorized parties can decode with a cipher decoder. In essence, it disguises data so it looks random to anyone who intercepts it.

The process relies on a cryptographic key, a secret value that both locks the data during encryption and unlocks it during decryption.

How Does Encryption Work?

Encryption turns understandable information into unreadable code by running it through a mathematical recipe called an algorithm. The readable input plaintext is mixed with a secret value, or key, and emerges as scrambled output known as ciphertext. Restoring the original data requires the matching decryption key; without it, the figures look like random noise.

Modern ciphers such as AES-256 illustrate the power of large key spaces: a 256-bit key yields 2^256 possibilities (about 10^77), far beyond the reach of brute-force guessing even for today’s supercomputers.

For contrast, consider a classic field cipher from World War II: the Vigenère cipher. Instead of shifting every letter by the same amount (as in Caesar’s method), Vigenère uses a repeating keyword, say, “FORT”, to rotate each character by different offsets.

An “H” with key letter “F” shifts six places to become “N,” while the next plaintext letter shifts by the numeric value of “O,” and so on. Anyone intercepting the message sees only a jumble of letters unless they already know (or can deduce) the keyword.

For example,

Plaintext: hello
Ciphertext (after encryption): dhjrnjrfkj

Types of Encryption

There are two types of encryption, namely:

1. Symmetric encryption (shared-key / private-key encryption)

A single secret key locks and unlocks the data. Because that same value performs both jobs, the algorithm can run quickly and with modest CPU or battery drain. Standards such as AES-256, ChaCha20, and 3DES fall into this camp and are well suited for bulk tasks: disk encryption, VPN tunnels, database fields, backups, and live-stream video.

The weakness is logistics; if the key is copied or intercepted during delivery, every past and future message protected by it becomes readable. To avoid that risk, organizations often wrap (“session-key”) traffic inside another, safer channel.

2. Asymmetric encryption (public-key cryptography)

Here, the task is split between two mathematically linked keys. The public key is shared freely and only encrypts; the paired private key, kept secret, handles decryption and digital signatures.

Algorithms such as RSA, Elliptic-Curve Cryptography (ECC), and Post-Quantum candidates rely on much larger key lengths and heavier computations. Hence, they’re generally reserved for short bursts: exchanging session keys, signing software updates, or protecting email headers.

Their big advantage is safety in transit, because the private key never travels, and an eavesdropper can record the encrypted data for years and still have nothing useful.

For a real-world look at how attackers blend symmetric (AES) and asymmetric (RSA) encryption, check out Group-IB’s analysis of the BlackCat ransomware affiliate program, which breaks down the gang’s C2 traffic to show both models side by side.

Why is encryption important?

Encryption matters because it turns raw data into useless noise for anyone who shouldn’t see it, while letting the right people flip it back. That single ability underpins nearly every modern promise of digital trust:

1. Keeps private things private

When messages, files, or database records are encrypted, interception doesn’t equal disclosure. Whether the eavesdropper is a coffee-shop Wi-Fi snooper or a rogue employee, the data they capture remains unreadable without the key.

2. Guards integrity in transit and at rest

Many encryption schemes include built-in integrity checks (e.g., AES-GCM, TLS record MACs). If someone tampers with the ciphertext, flipping bits, injecting malware, the decryption step fails, alerting you to foul play.

3. Proves identity and ownership

Public-key cryptography enables digital signatures. When your browser shows a padlock or you verify a document’s signature, you’re trusting encryption math to confirm “this came from the stated sender and hasn’t been altered.”

4. Enables safe e-commerce and online banking

Credit-card numbers, payment tokens, and one-time passwords race across the internet every second. Strong, end-to-end encryption makes that practical; without it, every hop between servers would be an opportunity for theft.

5. Protects data even after a breach

Disks, backup tapes, and stolen laptops regularly fall into the wrong hands. Full-disk and database-level encryption ensure that physical loss doesn’t automatically become a data-loss incident.

6. Meets legal and industry mandates

Regulations like GDPR, HIPAA, and PCI DSS explicitly require encryption for sensitive personal or financial data. Non-compliance invites fines, lawsuits, and brand damage.

7. Builds user trust

Consumers may not read a site’s privacy policy, but they recognize the HTTPS padlock and expect secure messaging apps to say “end-to-end encrypted.” Failing to provide that visible assurance can drive users elsewhere.

Also Read: Encrypted Symphony: Infiltrating the Cicada3301 Ransomware-as-a-Service Group

Historic Spotlight: The Data Encryption Standard (DES)

DES is a symmetric block cipher: one secret key both encrypts and decrypts, and it processes data in fixed-size blocks. Each block is exactly 64 bits – that’s eight ordinary text characters at a time.

The key is written as 64 bits, but every 8th bit is just a parity check, leaving 56 effective bits of real secrecy.

Why that matters: 2^56 possible keys once felt huge, but today it can be brute-forced in hours

High-level flow of encryption

Quick concrete example

• Plaintext block: “PAYLOAD!” (hex 0x5041594C4F414421)
• Key: 0x133457799BBCDFF1
• After the 16 rounds and inverse permutation, DES outputs 0x85E813540F0AB405.
  Feed that ciphertext and the same key back into DES in decrypt mode, and you get “PAYLOAD!” again, showing the symmetric nature.

Choose the Right Encryption Scheme for Everyday Tasks

With encryption is a toolkit, each job like storing a backup, protecting an email, securing an IoT sensor benefits from a different wrench. Below is a quick-reference guide you can scan when deciding what to use and why.

How to use this chart:

1. Identify the data flow (stored vs. in transit, human vs. machine).
2. Look up the row that matches your use case.
3. Adopt the listed tools or an equivalent library; stick to defaults unless you know you need custom settings.

For a clear, before-and-after illustration of real-world encryption and decryption, see Group-IB’s breakdown of DeadBolt ransomware, which walks through the ciphertext produced by the malware and the exact steps analysts used to unlock the data.

How Does Group-IB Help?

We’ve covered the essentials of modern data protection, from what encryption is and why symmetric or asymmetric ciphers fit different jobs.

How does Group-IB help?

Even with best-practice crypto in place, the hardest question is often: “How do I hand this secret to my colleague or customer without leaving it exposed in chat or email?”  That’s exactly the gap Secure Note fills.

• What is it? A free service that lets you paste text or upload a file, click Encrypt, and receive a one-time, self-destructing link.
• How does it work? The content is encrypted and hosted on Group-IB servers; once the link is opened, the data vanishes for good. 
• Why does it help? Secure Note is perfect for passing VPN keys, finance docs, or incident-response IOCs when you don’t have time to spin up a PGP exchange or a shared vault.

Quick demo: Open the tool, paste your secret, hit Encrypt, copy the link, and send it over your preferred channel, done in under 30 seconds. note.group-ib.com

Ready to Try?

Start using Secure Note now and make sure the only eyes on your sensitive data are the ones you intend.