Blog/Infosec 101/

Encryption and decryption

Dec 27, 2021

With the emergence of the first cipher, encryption was primarily used in war. When generals needed to send a message, they would encrypt it so only the intended target would be able to understand it. But now, encryption and decryption processes are all around us, like when you use your computer, smartphone, or the web. In this article, we will explain the basics of encryption and decryption.

What is encryption and decryption?

Encryption and decryption are the opposite ends of the same process. Encryption takes a plaintext message — anything you can read, watch, listen, and understand — and uses a set algorithms to turn the message into ciphertext, or unreadable data. Decryption is the reverse process, where the (hopefully) intended target deciphers the scrambled data back into a plaintext message.


  • Plaintext messages can be read and understood by anyone.
  • In ciphertext, data is scrambled and cannot be read without knowing the cipher.

How is encryption used?

Most of the time, encryption and decryption processes are invisible. You open your browser and click on a Gmail bookmark that opens your email. But there’s a lot more going on behind the scenes, including the browser protocols encrypting and decrypting the signal between the source (your computer) and the recipient (Gmail’s server), and vice versa.

Not all encryption is invisible and done in the background. You can use encryption with the help of apps like NordLocker to secure your files in a few clicks. You may not even have an intended recipient to send an encrypted message to and still find securing your data necessary.

Why use encryption?

There are a lot of security reasons to use encryption. For example, database encryption is immensely beneficial, and so are secure messaging and encrypted cloud services. But there’s another issue that is often overlooked. And it’s that the internet changed everything by turning private data into a sellable resource. Take a look at companies that keep challenging the limits of digital privacy and how much of it you can have. Not only that, but even the concept of ownership is now being tested:

  • Online services can do anything with your data and files
  • If you use Google Drive, Google Photos, Dropbox, or any cloud service that’s not end-to-end encrypted, you essentially give companies the right to rummage around your files and take whatever they like. Google is not even hiding the fact that they can and do scan and remove data from your Drive as they deem necessary.

  • The age of renting
  • Ironically, while companies try to get hold of everything you have, they’re extremely protective of what they own. The age of streaming made it very easy for companies to take away the media you paid for. No one came after your cassettes and CDs, but now, services like Google Movies and Apple Music have no problem deleting your library from their cloud if some corporate agreement is changed.

As you can see, encryption is essential not only for communications but also for protecting your data. It’s a bit like owning a hard copy of a book, image, or file. Encryption secures your digital possessions so no one can take them away because, without your permission, they can’t even know those possessions exist.

How different algorithms encrypt and decrypt data

There are several trusted encryption algorithms that encrypt and decrypt data differently. While encryption scrambles the data and decryption puts it back together, the way it's done in AES, RSA, ECC, and quantum encryption is different. Here’s a brief introduction to encryption algorithms and the way they work.

Symmetric encryption

Symmetric encryption is the simplest type of encryption. There’s a message and a secret cipher that transforms that message. But, even in cases of extremely strong encryption, if anyone finds out the secret cipher, they will be able to decrypt the message.

In symmetric cryptography, there are two ciphers you should know: stream ciphers, which encrypt messages symbol by symbol; and block ciphers, which encrypt and decrypt data in chunks.

AES (Advanced Encryption Standard), one of the world’s most popular encryption algorithms, is a block cipher. It takes a block of a plaintext message and applies a key to encrypt it. The result is ciphertext, which is encrypted again a pre-defined number of times based on that algorithm.

Asymmetric encryption

Asymmetric, or public key encryption, relies on public and secret keys that help verify the integrity of the communication channel. Let’s look at two examples from different asymmetric encryption algorithms:

  • RSA encryption uses prime factorization, a mathematical calculation that is easy to do one way (multiplying two numbers to get their prime factor), and hard another (deriving the two original numbers when only their prime factor is known).
  • ECC, or elliptic curve encryption, uses mathematical curves to derive its encryption keys. The principles of encryption and decryption stay the same, but ECC is simply more efficient than RSA or similar algorithms. For example, a 256-bit ECC key would offer the same security as a 3,072-bit RSA key.

Quantum encryption

Just like asymmetric cryptography, quantum encryption also requires the parties to exchange secret keys. In this case, it’s done by using light particles, specifically, their spin property.

  • First, the key is turned into binary code and, subsequently, into a sequence of light particles, or photons.
  • Next, the signal is encrypted by passing the photons through a filter which changes their spin.
  • Only the target who knows what filter was used and the order of photons will be able to decrypt the message and establish a private channel of communication.
  • Choose premium security and equip yourself with encryption. Try NordLocker for free to securely access and send your most personal files and information. Good security begins and ends with you.

Oliver Noble

Oliver Noble

Verified author

A nerd with a laser focus on all things cybersec. His own words. Oliver’s hobbies away from the computer include reading, Netflix, and testing the limits of yet another Raspberry Pi. To our surprise, this 130-pound ‘nerd’ also bakes a killer pumpkin pie.