Advanced Encryption Standard: An Easy Guide in 2021


Data is used everywhere and has become crucial in today’s world. With data becoming more and more important to all of us, its security also becomes a foremost concern. All industries and organizations, no matter how big or small, use data and that includes many sensitive and confidential information which cannot be seen by people who are not supposed to see it. This is where cybersecurity comes into the picture. There are several ways using which a data-set is made secure so that it is only used by people who are authorized to see it.

One of the fast and secure methods of encryption is the Advanced Encryption Standard- AES. It is a popular form of encryption that is used to keep most of the information and data safe. 

In this article, we will discuss what is the advanced encryption standard and it’s working in detail. 

  1. What is AES?
  2. Working
  3. Uses

1. What is AES?

Since people have realized that data is everything and we need to protect and save our information and communications from the world, there have been various forms of encryption that have been used. The earliest type of encryption used different codes for each alphabet and with the evolution of encryption, AES was built. 

AES is a universal standard for encryption used in various types of data as industries. It is a 128-bit encryption system which replaced the Data Encryption Standard (DES), which was a 56-bit encryption. People realized that the 56-bit encryption was too easy to break with the advancement in computers and increasing computing power, which led to the advanced encryption standard algorithm. 

This new encryption standard was selected using a competition held by the National Institute of Standards and Technology (NIST). The objective of the competition was to develop an algorithm which will be secure enough to protect government information until the next century. International cryptographic experts were present and checked each algorithm with extreme scrutiny, and finally, AES was selected. In the next section, we will try to understand how advanced encryption standard works. 

2. Working 

The Advanced Encryption Standard algorithm steps can be complicated for people who are not well versed in encryption, but we will try to break it down into simple steps. 

1. Data is separated into blocks 

The first thing that happens in this encryption is that the text or the information that is to be encrypted is separated into blocks. The block size is of 128-bits, so the data is separated into a 4×4 column of 16 bytes. Since there are 8 bits in one byte, so 16 bytes equal to 128 bits. 

2. Key Expansion 

In the next step of key expansion, the initial key is used to come with a series of other keys for each round of the process of encryption. This leads to 128-bit new round keys which are derived from a method called the Rijndael key schedule. This is just a fast way of producing new key cyphers. 

So the newly produced keys look like random characters, but have been derived from a carefully structured process of AES and play a huge role in encryption. 

3. Add Round Key 

In this step, the initial key which came in the previous steps is added to the message. This step is done using an algorithm for additive encryption, XOR cypher. The keys are added in the binary system. 

4. Substitute Bytes 

Now, each byte is substituted using a pre-decided table. This is a complicated system as there is an already established table available that is used by the algorithm to determine what each byte will be substituted too. 

For example, the table can say the ‘h3’ becomes ‘jb’ or ‘s8’ becomes ‘9f’ and so one. This does not have a lot of logic attached to it, but it is a way of finding substitute keys for each byte. 

5. Shift Rows 

The name of this step clearly explains what happens. All the rows are shifted to new positions depending on the algorithm and so a new table is built. 

6. Change Columns

This is again a complicated step of the process involving math operations. To put it simply a specific mathematical operation is applied to each column to diffuse it even further. 

6. Add Round Key Again 

Now after getting the results from applying the mathematical operation to the columns, we’ll add the round key again. The same round key is used which was derived earlier using the Rijndael key schedule. 

7. Continue for many rounds 

Until step 6, we just finished one round. After adding the last round key, it goes back to the byte substitution stage and again each byte is substituted using a predetermined table and all the steps are repeated. 

When a 128-bit key is being used, the process is repeated 9 times.  Depending on the strength of AES, the number of rounds changes. 

3. Uses

AES has become the most widely used encryption algorithm in the world, as the US government adopted it. There are several advantages of advanced encryption standard because of which this has happened. There is data that shows that AES protects more than half of the data in the world. This encryption algorithm is used by everyone from Apple to NASA. AES is involved in keeping your information protected from attackers on many websites including Netflix. 


Using and having confidential and important data means having to protect it. It is extremely crucial that we take all steps in a power to protect our data and information from attackers and hackers that misuse the information in any way. There are many available encryption methods and algorithms that are used. One such globally accepted algorithm is the Advanced Encryption Standard AES. 

This article explained what AES is and how it works. AES is a 128-bit encryption algorithm which is widely adopted all around the world including the US government. We also discussed several advanced encryption standard applications and learned how AES is protecting our information and identity from attackers. It is important to understand how and how well our data is being protected and which systems we are using for our safety. 

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give them an edge in this competitive world.


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