What is AES Encryption and How Does It Work [Detailed Guide]

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AES Encryption - In-depth Guide

Today we live in a world of data where humans produce around 2.5 quintillion bytes of data everyday. For perspective, that is 2.5 followed by 18 zeros. With data being produced everyday, there are bound to be security issues. The cost of an average data breach in 2021 was estimated to be around 4.24 million US dollars. The more alarming trend is that this cost is a 10% rise from 2019.

These are the times when you need robust security systems. A strong encryption system is the bedrock of a robust digital security system. Today we are going to talk about the advanced encryption standard or AES which has become the encryption standard of choice for institutions that manage sensitive data.

In this blog we will throw some light on the following aspects of AES encryption algorithm

  • What is AES encryption?
  • How secure is AES encryption?
  • Why was the AES encryption algorithm necessary?
  • Benefits of AES
  • How does AES encryption work?
  • Some examples of AES encryption

How secure is AES encryption?

The AES encryption algorithm is an algorithm that is really hard to crack. How hard? It is estimated that even the fastest supercomputer in the world would require more than 100 trillion years to break the encryption of AES with a brute force attack. Even Quantum computers will take at least six months to break an AES algorithm.

According to many experts AES is one of the most secure encryption algorithms ever created. The creators of AES have made it publicly available. This creates suspicion in the minds of many people that how secure can an algorithm be if it’s open source? Another way of looking at this is that the makers of this algorithm are so confident that they released it to the public. Another thing worth noting is that right from Federal agencies to the military most of these organizations still use the AES encryption standard. If they stop using it then we might think that something is not right. But their continued use of the AES algorithm in cryptography suggests that everything is fine.

What is AES encryption?

The Advanced Encryption Standard, or AES, is a method for encrypting data in a way that is much stronger than traditional methods. The first version of the standard was released in 1996 and has been improved on several times since then to keep up with the needs of today’s data security requirements.  The basic premise of the AES standard is to use a series of rotations and substitutions to transform plaintext data into ciphertext. This process is known as encryption.

Aes is a symmetric algorithm which uses the same key for both encryption and decryption, and which was originally designed for military and government use. The key size is usually 128 bytes (16 bits) and is typically changed very infrequently to provide maximal protection against brute force attacks.

The National Institute for Standards and Technology(NIST) is the government organization that is responsible for publishing and maintaining AES. In fact AES is one of the many NIST issued federal information processing standards. All these standards are approved by the US secretary of commerce before publication. AES is the only available block cipher that is approved by the National Security Agency(NSA) to transmit secret information across government agencies.

The AES encryption online algorithm has become the cryptographic technology of choice for people who want to securely encrypt their data. Federal government agencies as well as non-government agencies use the AES encryption daily in order to protect their sensitive data.

The following Is a graphical illustration of the AES algorithm at work

How AES Algorithm Works

A sender sends a plain text file to an encryption server. On this server a AES secret key is used to encrypt the plain text data into ciphertext data. The receiver of the file can only read the contents of the file if he has the secret key to open the file.

Why Was the AES Encryption Algorithm necessary?

The DES (Data Encryption Standard) encryption algorithm was the predecessor to the AES encryption algorithm. While it was sufficient for the needs of the generation of computers when it was created, with every passing year it became very easy for hackers to break into the DES algorithm. We have shown that in the below image.

Chronology of DES Cracking

Thus the need for a stronger encryption algorithm arose. The security researchers first tried by creating a triple DES algorithm. The things that did not work out as planned as the base of this algorithm was excruciatingly slow. Hence the researchers went in a new direction and decided to create an altogether new algorithm. AES has longer key sizes and stronger ciphers than the DES algorithm.

Benefits of the AES

  • Ever since its inception, the AES algorithm has proven its worth as a reliable security mechanism. Here are some of the major benefits of using the AES algorithm
  • Engineers can implement the AES algorithm both in software as well as hardware.
  • Being open-source the AES algorithm can be accessed both by private as well as public sectors.
  • The AES algorithm is extremely resilient against hacking attempts.
  • AES encryption algorithm is the most commonly used security protocol in the world today.

How does AES encryption work?

Here is a brief overview of how the AES encryption mechanism works. The major design principle of AES is known as the substitution permutation network. The substitution permutation network refers to a series of mathematical operations linked with each other. The network works by applying a lot of layers of substitution boxes and permutation boxes to play in text. This process produces the cipher text block. The ciphertext is an unreadable conversion of plain text data. Humans cannot read the AES ciphertext until they have the correct AES key used to decrypt the data.

AES has three key sizes

  • 128
  • 192
  • 256

Although the key length of the AESA encryption algorithm varies; the block size is always 128 bits. Many of you might wonder why there are different key lengths? A lot of you might also have the question that if the 256 bit key is the strongest of the lot, then why don’t we just use this single key instead of the other two?

The thing is, there are resource constraints. For instance if you have a mobile app that uses the AES-256 instead of the AES-128 then it will drain the phone’s battery faster. Hence in case your app does not require a higher level of encryption, it is best to go with a lower level of encryption to save on resources utilized.

Example of how AES encryption looks like:

Can you decipher the following ciphertext message?


No? Thought so. Here is the plain text version

Plaintext message: The acting president was diagnosed with a potentially terminal illness.

You can only decipher the message if you have the correct AES encryption key.

What are some examples of AES encryption?

It’s not that the AES algorithm is used only by Federal agencies, today we find many everyday uses of the AES algorithm. You might be surprised to find out that many solid state drives (SSDs) are already employing the AES encryption algorithms. This ensures that the data is encrypted and protected from the moment the SSD is produced in the factory.

Many SSD manufacturers equip their hard drives with a 256-bit AES hardware based encryption, keeping hackers out of the equation.

Virtual private networks or VPNs as they are popularly known employ the Pratik encryption standard. VPNs are used to securely connect you with another server generally located in another country. As the VPNs have to dynamically switch between servers; they can afford to use only the best methods of encryption. Popular VPN services like NordVPN and ExpressVPN use the AES-256 bit key to secure the browsing data of their customers.

Your social media messages are also encrypted. So that you do not need to worry about someone reading your messages and extracting critical information about you from those messages. Popular social media messaging platform WhatsApp employs AES algorithm. WhatsApp encrypts its messages using a 256 bit AES encryption. This makes it extremely difficult for hackers to hack into your WhatsApp messages.

The world’s favorite desktop operating system, Windows also uses the AES 128 bit and 256 bit encryption.

All data stored in Google cloud is encrypted using a 256 bit AES encryption by default.

LastPass is one of the most famous password management applications. LastPass uses AES encryption. The AES encryption helps LastPass to keep the user’s password safe from hackers. Even Lastpass employees cannot access the password of users.

The US military, national security agency and many other US government entities use AES encryption to secure data storage.

A classic example of the AES encryption in action is your internet browser. Whenever you visit a website with https in its URL then it is very likely that the website is secured by a TLS / SSL certificate. This means that the website uses AES encryption to maintain the security and integrity of your browsing sessions. Another common use of the AES algorithm is in Wi-Fi. Wi-Fi is secured by WPA2-PSK (AES) encryption. Even Facebook messenger uses the AES encryption standard.

Final words

The AES encryption standard has become the gold standard for encrypting sensitive data across a wide range of applications. If you are thinking about building an app that deals with sensitive data, then it is best to consider the security mechanism that the app will have. The AES encryption standard is just one of the many robust encryption standards available. Understand that you need to select the most appropriate encryption standard to ensure that your app performs optimally. You can take expert opinion for this.

Janki Mehta

Janki Mehta is a Cyber-Security Enthusiast who constantly updates herself with new advancements in the Web/Cyber Security niche. Along with theoretical knowledge, she also implements her practical expertise in day-to-day tasks and helps others to protect themselves from threats.