What’s the AES-256 Encryption and How does it work?

AES is the current data encryption standard. The level of security and protection it offers is unmatched by Symmetric key encryption and Block cipher.

Table of Contents

The Advanced Encryption Standard (previously referred to as Rijndael) is one manner to encrypt information. It is so secure that even brute pressure cannot damage it.

This advanced encryption standard is used by the US National Security Agency and various industries including online banking. What is AES encryption and how does it work? Let’s find out!

What Is AES-256 Encryption?

AES is the current data encryption standard. The level of security and protection it offers is unmatched.

Let’s break it down. AES is a

  • Symmetric key encryption
  • Block cipher

Symmetric And Asymmetric Encryption

AES is a symmetric encryption type.


“Symmetrical” means that the same information is used for encryption and decryption keys. Also, both sender and recipient details need a copy of your decryption password.

Asymmetric critical systems, on the other hand, use two processes for each different one: Encryption and decryption.

The advantages of a symmetric system like AES are that they are much faster than non-symmetric ones.

This is because symmetric key algorithms require less computing power. Therefore, asymmetric keys are best used for external file transfers. Symmetric keys are better suited for internal encryption.

What Is A Block Cipher?

In fact, AES is also what the tech world calls a “block cipher”.

It’s called “block” because this type of encryption divides the information to be encrypted (called plaintext) into parts called blocks.

Actually, AES uses a block size of 128 bits.

This means that the data is divided into four-by-four arrays containing 16 bytes. Each byte contains eight bits.

Therefore 16 bytes multiplied by 8 bits gives a total of 128 bits per block.

Regardless of this division, the size of the encrypted data remains the same. In other words, 128-bit plaintext produces 128-bit ciphertext.

The Secret Of The AES Algorithm

Now grab your hat because this is where it gets interesting.

Joan Daemen and Vincent Rijmen developed the algorithm using the Permutation Network (SPN).

SPNS encrypts the data by applying multiple rounds of key expansion.

The initial key is used to create a new set of keys called “round keys”.

We’ll learn more about how these round keys are generated later. It can be said that multiple rounds of modifications generate a new round key each time.

With each round, the data becomes more secure and the encryption harder to crack.


Because these encryption rounds make AES impenetrable! There are too many rounds for the hacker to crack.

Let’s put it this way: It would take a supercomputer longer than the supposed age of the universe to crack the AES code.

So far, AES has hardly posed a threat.

Different Key Lengths

There are three lengths of AES encryption keys. Each key length has a different number of possible key combinations:

  • 128-bit key length: 3.4 x 1038
  • 192-bit key length: 6.2 x 1057
  • 256-bit key length: 1.1 x 1077

Although the key length of this encryption method varies, the block size of 128 bits (or 16 bytes) remains the same.

Why are the key sizes different? Using AES 256 bits instead of AES 128 requires more processing power.

The practical effect is that more raw battery power is required, so the phone drains faster.

Although AES 256-bit encryption is the gold standard, it is not suitable for everyday use.

Where Is The Advanced Encryption Standard (AES) Used?

AES is one of the most trusted systems in the world. It has been widely used in many industries that require an extremely high level of security.

Today, AES libraries have been created for various programming languages ​​including C, C++, Java, Javascript, and Python.

The AES encryption standard is also used by various file compression programs, including 7 Zip, WinZip, and RAR, as well as by disk encryption systems such as BitLocker and FileVault; And file systems like NTFS.

You may already be using it in your everyday life without realizing it!

AES is an important tool for database encryption and VPN systems.

If you rely on a password manager to remember the credentials for your multiple accounts, you’ve probably already come across AES.

What messaging apps do you use e.g. B. WhatsApp and Facebook Messenger? Yes, they use it too.

Even video games like Grand Theft Auto IV use AES to protect against hackers.

The AES instruction set is built into all Intel and AMD processors, so it’s already built into your PC or laptop and you don’t have to do anything.

Let’s not forget, of course, that your app bank is designed to allow you to manage your finances online.

Once you understand how AES encryption works, you’ll breathe easier knowing your information is safe!

History Of AES Encryption

AES began in response to the needs of the United States government.

As early as 1977, federal agencies relied on Data Encryption Standard D (DES) as their primary encryption algorithm.

However, in the 1990s, DES was no longer secure enough as it could only be cracked for 22 hours.

Therefore, the government announced an open competition to find a new system that would last more than five years.

The benefit of this open process is that any encryption algorithm submitted may be subject to public safety concerns. This means that the government can be 100% sure that there are no backdoors in their winning system.

Because multiple heads and eyes are involved, the government also maximizes the ability to identify and fix bugs.

Finally, Rijndael Cryptography (also known as today’s Advanced Encryption Standard) was crowned champion.

Rijndael is named after the two Belgian cryptographers who founded it, Vincent Rijmen and Joan Daemen.

The Advanced Encryption Standard changed its name in 2002 and was published by the National Institute of Standards and Technology (NIST).

The NSA approved the AES algorithm for processing power and security of top-secret information. This brings AES to the map.

Since then, AES has become the industry standard for encryption.

Its open nature means that AES software can be used for public and private, commercial and non-commercial applications.

How Does AES 256 Work?

So far we know that these encryption algorithms can compromise the information they protect, turning it into a random mess.

So the basic principle of any encryption is that each data unit is replaced by another data unit depending on the security key.

But what exactly makes AES encryption secure enough to be considered an industry standard?

1. Description of the process for AES 256

The AES encryption algorithm goes through multiple rounds of encryption. It can even go 9, 11, or 13 rounds.

Each round involves the same steps below.

  • Divide the data into blocks.
  • Key extension.
  • Add round keys.
  • Replace/replace bytes.
  • Mobile line.
  • Mixed column.
  • Add the round key again.
  • Do it again.

After the last round, the algorithm plays another round. For this set, the algorithm executes steps 1 through 7 divided by step 6.

Change step 6 as it doesn’t do much at this point. You’ve gone through this process many times.

Therefore repeating step 6 would be superfluous. The processing power required to reshuffle the columns isn’t worth it because it doesn’t change the data significantly anymore.

At this point, the data will have gone through the following rounds:

  • 128-bit key: 10 rounds
  • 192-bit key: 12 rounds
  • 256-bit key: 14 rounds


Unordered character sets are meaningless to anyone without an AES key.

2. Further Observation

You have already seen how symmetric block ciphers are made. Let’s take a closer look.

First, these encryption algorithms use XOR (“XOR”) passwords.

This password is an operation built into the processor hardware.

Then each data byte is replaced by another.

This critical step follows a predetermined table, called the Rijndael critical program, to determine how each change is to be made.

Now you have a new 128-bit round key and it’s a jumble of letters.

Next, it’s time to pass the first round of AES encryption. The algorithm adds the initial key to the new round key.

You now have a second random code.

The algorithm replaces each byte according to the Rijndael S-Box code.

Now, it’s time to move the row 4 by 4 array.

  • The first row stays the same.
  • The second line moves one space to the left.
  • The third line is moved to two Spaces.
  • Finally, the fourth is moved to three Spaces.

Each column is multiplied by a predefined matrix, which in turn gives you a new block of code.

We won’t go into detail as this is an extremely complex process that requires a lot of advanced mathematics.

Columns that only know the passwords are shuffled and matched to create another block.

Finally, add the round key to the block (just like the initial key in step 3).

Then rinse and repeat as many rounds as needed.

This process is repeated a few more times, resulting in ciphertext that is fundamentally different from plaintext.

To crack it, do the whole operation in reverse order!

Each stage of the AES encryption algorithm has an important function.

3. Why All Steps?

Using a different key for each round gives you more complex results and protects your data from brute force attacks, no matter what key size you use.

The byte replacement process modifies data in a non-linear manner. This hides the original and encrypted relationship content.

By shifting the rows and shuffling the columns, the data is distributed. Toggling is horizontal propagation of the data while shuffling is vertical propagation.

By transposing the bytes, you get a more complex encoding.

The result is an extremely complex form of encryption that can only be cracked if you have the key.

Is AES Encryption Secure?

If our description of the process isn’t enough to convince you of the power of AES keys, let’s take a closer look at AES security.

As we said at the beginning, the National Institute of Standards and Technology (NIST) has selected three AES: 128-bit AES, 192-bit, and 256-bit keys.

Each type still uses the same 128-bit block, but they differ in two ways.

1. Key length

The first difference is the length of each bit key.

As the longest encryption, 256-bit AES encryption offers the strongest level of encryption.

This is because 256-bit AES encryption requires hackers to try 2,256 different combinations to ensure the right content is included.

We must emphasize that this number is astronomical. That’s a total of 78 digits!

If you don’t understand how big it is, let’s put it that way. It’s too big, exponentially larger than the number of atoms in the observable universe.

Apparently, to protect national security and other data, the US government requires 128-bit or 256-bit encryption methods for sensitive data.

Aes-256, which has a key length of 256 bits, supports the largest bit size and is almost impossible to brute force by today’s standards of computing power, making it the most powerful encryption standard available today.

Key SizePossible Combinations
1 bit2
2 bit4
4 bit16
8 bit256
16 bit65536
32 bit4.2 10points¯x9
56 bit (DES)7.2 10points¯x16
64 bit1.8 10points¯x19
128 bit (AES)3.4 10points¯x38
192 bit (AES)6.2 10points¯x57
256 bit (AES)1.1 10points¯x77

2. Encryption Rounds

The second difference between these three AES variants is the number of rounds of encryption they have gone through.

AES 128-bit encryption uses 10 rounds, AES 192 uses 12 rounds, and AES 256 uses 14 rounds.

As you might have guessed, the more rounds you use, the more complex the encryption becomes. This makes AES 256 the most secure implementation of AES in the first place.

Can Hackers Break AES 256?

The old 56-bit DES key can be cracked in less than a day. But for AES? It would take billions of years to achieve a breakthrough with today’s computing technologies.

It would be foolish for a hacker to even attempt this type of attack.

However, we have to admit that no encryption system is completely secure.

Researchers studying AES have found some potential ways.

Threat #1: Related Key Attack

In 2009, they discovered a possible related key attack. Instead of brute force, these attacks target the encryption key itself.

This type of cryptanalysis attempts to crack a cipher by looking at how it uses different keys.

Fortunately, the relevant key attack is only a threat to AES systems. It can only work if the hacker knows (or suspects) the relationship between the two sets of keys.

Rest assured that after these attacks, cryptographers are rapidly increasing the complexity of the AES key plan to prevent them.

Threat #2: Known Key Discrimination Attack

Unlike brute force, this attack uses known keys to decrypt encrypted structures.

However, the attack only targeted the eight-round version of the AES 128, not the standard 10-round version. However, this is not the main threat.

Threat #3: Side-channel attack

This is a big risk for AES. It works by trying to get any information that the system reveals.

Hackers can listen to noise, electromagnetic signals, time information, or power consumption to find out how security algorithms work.

The best way to prevent side-channel attacks is to eliminate information leaks or to mask the leaked data (by generating additional electromagnetic signals or sounds).

Threat #4: Reveal The Key

This is easily proven by doing the following:

  • A strong password
  • Multi-factor authentication
  • A firewall
  • Antivirus software

Also, train your employees to defend themselves against social engineering and phishing attacks.

Advantages Of AES Encryption

The AES encryption process is easy to understand. This allows for easy implementation and very fast encryption and decryption times.

In addition, AES requires less memory than other encryption types (e.g. DES).

Finally, whenever you need an extra layer of security, you can easily combine AES with different security protocols like WPA2 or even other types of encryption like SSL.

AES And ChaCha20

AES has some limitations that other types of encryption try to circumvent.

While AES is great for most modern computers, it’s not built into our phones or tablets.

For this reason, AES on mobile devices is usually implemented via software (rather than hardware). Devices.

However, the software implementation of AES consumes too much battery power.

ChaCha20 also uses a 256-bit key. It was developed by various Google engineers to fill the gap.

1. Advantages Of ChaCha20

  • More CPU friendly
  • Easy to implement
  • Less power is needed
  • More secure against cache time attacks
  • It is also a 256-bit key

AES And Twofish

Twofish is one of the finalists in a government-run competition to replace DE.

Twofish uses Feistel nets instead of blocks. This means that it is a similar but more complex version of older standards like DES.

To date, Twofish is intact. Given the potential threats mentioned above, many people say it is more secure than AES.

The main difference is that AES varies the number of encryption rounds depending on the length of the key, while Twofish keeps it constant at 16 rounds.

However, Pisces requires more memory and performance than AES, which is the main disadvantage when using low-end or mobile computing devices.


If AES encryption is good enough for the NSA, we’re happy to trust your security.

Although many technologies are available today, AES continues to lead. Any company can use it to access top secret information.



DiskMFR Field Sales Manager - Leo

It’s Leo Zhi. He was born on August 1987. Major in Electronic Engineering & Business English, He is an Enthusiastic professional, a responsible person, and computer hardware & software literate. Proficient in NAND flash products for more than 10 years, critical thinking skills, outstanding leadership, excellent Teamwork, and interpersonal skills.  Understanding customer technical queries and issues, providing initial analysis and solutions. If you have any queries, Please feel free to let me know, Thanks

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