What is cryptography, and how does it work?

Anton P. | June 16, 2021

Cryptography is all about the techniques supporting private and secure communications. It dates back to secrecy attempts in ancient Greece when the Spartans used scytales to exchange inside information. Senders would wrap parchment with the intended message around a wooden stick and send it to the recipient. Both of them had sticks identical in thickness to decrypt the message.

What is cryptography, and how does it work?

Modern cryptography might not use sticks, but the end goal remains the same. It attempts to preserve the integrity of data and curb snoops from reading it. However, cryptography is much more than encryption. Although it’s shrouded in technical jargon, it is an essential subject for all.

Cryptography defined

Cryptography is the study of techniques and procedures used to secure information by making it unreadable to unintended recipients. Other sources regard cryptography as the art of creating and understanding codes. While this description partially represents it, it is not entirely accurate. Nowadays, cryptography has evolved and deals with so much more than that.

Cryptography also captures the mechanisms applied to warrant data integrity, exchange of secret keys, and protocols used for authentication. Thus, a more inclusive description discusses it as a study of mathematical processes for protecting digital information and systems. In general, it is one of the central topics in computer science, and you have undoubtedly experienced its benefits. Here are a few scenarios where cryptography played a massive role in safeguarding your communication:

  • Logged in to your account by providing your credentials.
  • Bought something online via your credit card.
  • Downloaded a verified update for your OS.
  • Sent a message to your friend via instant messaging platforms.

Is it the same as encryption?

Cryptography and encryption are terms that many might treat as synonymous. However, cryptography is a broad term encompassing so much more than encryption. It deals with everything related to secure communications and data integrity. On the other hand, encryption is the mathematical process used to encode a message with an algorithm.

Thus, encryption is a fundamental concept in cryptography. However, cryptography is a field of study, meaning it covers many concepts and technologies.

Goals of cryptography

When discussing objectives of cryptography, experts typically use the PAIN abbreviation:

  • P stands for Privacy. No one besides the intended recipient and the sender should be able to read their exchanged messages.
  • A stands for Authentication. During the information exchange, both participants and data sources need authentication.
  • I stands for Integrity. The message must arrive in its original form. Bystanders or eavesdroppers should not be able to modify, alter or delete the contents of messages.
  • N stands for Non-repudiation. Entities involved in digital communications should not be able to deny their involvement.

Cryptography over the years

Cryptography was not always the sophisticated science of mathematics. One of the first attempts to safeguard confidential information relates to alphabet manipulation.

The Caesar cipher dictated to substitute letters with different ones by moving a fixed number of places down the alphabet. This letter-shifting strategy is one of the most famous forms of encryption. However, it is also easy to crack as long as the perpetrator figures out the number of places moved.

Over the years, different approaches have been adopted. However, researchers claim that the birth of modern cryptography came in late in the 20th century. Before then, this science was, in fact, an art, as people constructed codes with very little theory. Despite its humble beginnings, cryptography finally received the attention it deserved in the 1970s and 1980s. Developers began experimenting with it and magnifying its significance in computer security.

Another significant feature of modern cryptography is its application. Initially, its integration was an exclusive ordeal, available only to military organizations and governments. Now, cryptography refers to a set of tools and practices that are almost impossible to miss.

Asymmetric cryptography

Public-key cryptography is a system that equips two keys: public and private ones. Cryptographic keys are terms that relate to a piece of data used to scramble information. Typically, it refers to randomly generated numbers or a string of characters (numbers and letters).

Thus, asymmetric cryptography assigns two of these keys to each user. When a specific mechanism applies the key and the encryption algorithm, the plaintext data transforms into gibberish. However, in this case, the user’s private key is the basis from which the public key gets generated. Then, the public key is accessible to anyone, while the private key remains secret.

In general, anyone can encrypt a message using the receiver’s public key. But, then, only the recipient’s private key can decipher its content, meaning that others will only see the scrambled version.

In addition to sending private messages, asymmetric cryptography is present in the technology behind digital signatures, digital cash, and time-stamping services.

Symmetric cryptography

Symmetric-key cryptography refers to systems that use only one key to both encrypt and decrypt digital data. Recipients and senders possess the same keys but do not share them with anyone. Thus, the requirement here is that the senders and intended receivers have access to the shared secret key.

There are two types of symmetric cryptography:

  • Stream ciphers. This method implies that each character (letter or digit) gets encrypted one at a time.
  • Block ciphers. This technique scrambles a number of characters as a single unit.


Hashing is a bit different from symmetric and asymmetric cryptography. In this case, systems do not supply an option for decrypting information. Let us explain.

By definition, hashing is the process of transforming information into a different form. It generates the new value by employing mathematical algorithms. So far, the process resembles the techniques discussed above. It takes data in plaintext and converts it into gibberish.

However, encryption is a process that generates keys both for scrambling and deciphering data. Hashing is a one-way function, meaning that the result of hashing is irreversible. Thus, you can notice this process applied by various companies to store users’ credentials safely. With an adequately designated algorithm, hashing is a viable option used across multiple industries.

End-to-end encryption

End-to-end encryption is a subject that receives a lot of attention. Some applaud this innovative data protection, and others raise concerns. Despite these hurdles, end-to-end encryption has slowly evolved into a requirement for many users. For instance, many might opt for messaging apps that end-to-end encrypt their communications. If not, their communications are readable by the service providers.

By definition, end-to-end encryption means that the message you send gets decrypted by its recipient. However, in this case, no one, not even the service providers, can view the contents of your messages. The traditional TLS protocol still allows the main servers (the service providers) to access content in its plaintext form. With end-to-end, they cannot.

Nevertheless, services that use end-to-end encryption might still retain access to metadata. For instance, they can still know who you communicate with, just not what you actually discuss.

Cryptography and Virtual Private Networks

Principles of cryptography empower VPN tools with the capabilities necessary to safeguard users’ digital lives. For instance, Atlas VPN uses a range of technologies and methods to warrant security and privacy. Potentially the biggest influence comes from the AES-256 encryption. Initially, government and military institutions adopted AES to protect confidential information. Now, regular users can take advantage of its sophisticated protection for their everyday needs.

AES represents a symmetric-key algorithm by nature, meaning a single key accomplishes both encryption and decryption processes. We chose this option because it guarantees the best balance between high-speed connections and robust protection.

Final notes

Cryptography is central in providing secure communications online. It has evolved and entered new channels to deny access and preserve the integrity of information.

Now, its application involves everyone visiting the web. While there are multiple schools of thought, encryption is one of the foundations of privacy. Companies and governments should work to preserve it, and collaborate with experts to build secure communication channels.

Anton P.

Anton P.

Former chef and the head of Atlas VPN blog team. He's an experienced cybersecurity expert with a background of technical content writing.


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