Advanced Encryption Standard (AES): How does it work?

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• 3 min read
Advanced Encryption Standard (AES): How does it work?

With cyber threats becoming increasingly sophisticated, companies are constantly looking for more effective ways to protect sensitive information. In this scenario, one of the widely used methods is the Advanced Encryption Standard (AES).

But what exactly is AES, and how does it work?

In this article, we’ll explain its importance and how it keeps data secure. Keep reading!

What is AES – Advanced Encryption Standard?

The Advanced Encryption Standard (AES) is a data encryption method developed by two Belgian cryptographers, Joan Daemen and Vincent Rijmen, in the late 1990s. It was selected by the National Institute of Standards and Technology (NIST) in the U.S. in 2001 to become the official data encryption standard. This decision was made because its predecessor, the Data Encryption Standard (DES), had become outdated and vulnerable to attacks due to technological advancements.

The key feature of AES is that it is symmetric, meaning the same key is used for both encryption and decryption. This differs from asymmetric encryption algorithms, such as RSA, where two different keys (public and private) are used.

Because of its symmetric nature, AES is highly efficient for tasks like securing wireless communications, protecting confidential files, and encrypting databases.

Also read:

🔹 Understanding How Encryption Works in Practice

How Does the Advanced Encryption Standard Work?

AES works by taking plaintext data (the original message) and converting it into ciphertext (a scrambled version of the message) through a series of mathematical operations. Here’s how it works:

Block Encryption

AES divides data into fixed-size blocks of 128 bits (16 bytes). This means that encryption is performed on chunks of data at a time rather than encrypting the entire message all at once.

Key Length

AES supports different key lengths: 128, 192, or 256 bits. The longer the key, the stronger the encryption, but it also requires more computational power.

  • 128-bit keys: Secure for most purposes
  • 192-bit keys: Higher security level
  • 256-bit keys: Extra security for highly sensitive information (e.g., government or military data)

Encryption Rounds

AES encrypts data in multiple stages, known as "rounds." The number of rounds depends on the key length:

  • 10 rounds for 128-bit keys
  • 12 rounds for 192-bit keys
  • 14 rounds for 256-bit keys

Each round further scrambles the data, making it harder for unauthorized users to decipher.

Here are the basic steps AES follows in each round:

  1. SubBytes: Each byte in the data block is replaced using a fixed table called the S-box, adding confusion to the encryption process.
  2. ShiftRows: Rows of the data block are shifted to the left by a certain number of positions, further scrambling the information.
  3. MixColumns: Columns of the block are mixed using mathematical operations, making the data even more unrecognizable.
  4. AddRoundKey: The encryption key (which has been expanded into multiple "round keys") is applied to the data using the XOR (exclusive OR) operation, ensuring only those with the correct key can decrypt the message.

How Strong is the Advanced Encryption Standard?

The strength of AES comes from both the number of encryption rounds and the key length. Longer keys and more rounds mean stronger security but also require more processing power.

For example, a 128-bit key has 2¹²⁸ possible combinations—approximately 340 undecillion combinations (a 340 followed by 36 zeros). Breaking this with a brute-force attack, where a computer tries every possible key combination, would take an unimaginably long time, even with today’s most powerful computers. A 256-bit key is even more secure, with exponentially more possible combinations.

However, improper use or incorrect implementation of AES can pose serious risks. Even with a strong encryption key, if the key is not well-protected or the encryption setup is flawed (e.g., predictable keys, insecure storage), the system can become vulnerable. Additionally, software vulnerabilities or the use of outdated encryption algorithms can compromise security.

That’s why AES security depends not only on its theoretical strength but also on proper implementation and ongoing maintenance to prevent potential weaknesses.

Final Thoughts

As mentioned, AES is a robust and widely trusted encryption algorithm used to protect data across various sectors.

In the United States, AES is the official encryption standard used by the government and is widely adopted in industries such as finance, technology, and defense. In Brazil, although there is no regulation mandating AES as the standard, it is widely used by banks, technology companies, and telecommunications firms to secure transactions, communications, and data storage.

However, it’s crucial to highlight that the effectiveness of AES depends on its proper implementation and adherence to security best practices. Continuous attention is needed to avoid vulnerabilities that could compromise data protection.

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