Close this search box.

Network Security: Advanced Encryption Standard (AES)

Photo by cottonbro studio on

Discover the Advanced Encryption Standard (AES) in this comprehensive article. Explore the operation, key features, and advantages of AES, a widely adopted symmetric encryption algorithm. Learn about its security, efficiency, key expansion process, and various transformations involved in encryption and decryption. Gain insights into the versatility and compatibility of AES, making it the encryption standard of choice for securing sensitive data in diverse applications.

Before moving ahead let’s take a look at Introduction To Fiestal Structure.

Table of Contents

Advanced Encryption Standard (AES)

The Advanced Encryption Standard (AES) is a widely adopted symmetric encryption algorithm used to secure sensitive data. It was selected by the National Institute of Standards and Technology (NIST) in 2001 as the successor to the Data Encryption Standard (DES) due to its superior security and efficiency.

AES operates on fixed-size blocks of data and supports three key sizes: 128 bits, 192 bits, and 256 bits. The algorithm used by AES is the Symmetric-key algorithm, meaning that the same key is used for the encryption and decryption of data.

Some key features of AES

Security: AES is considered highly secure and has withstood rigorous scrutiny from the cryptographic community. It offers a high level of resistance against various cryptographic attacks, including brute-force, differential, and linear attacks.

Key Sizes: AES supports key sizes of 128, 192, and 256 bits, providing flexibility in choosing the appropriate level of security for different applications. The larger key sizes offer stronger encryption and make brute-force attacks computationally infeasible.

Efficiency: AES is designed to be computationally efficient, allowing for fast encryption and decryption operations. It has optimized implementations on various hardware and software platforms, making it suitable for a wide range of applications.

Standardization and Compatibility: AES is an international standard adopted by numerous organizations and industries. It is widely supported in cryptographic libraries, frameworks, and hardware devices, ensuring compatibility and interoperability across different systems.

Versatility: AES can be implemented in various modes of operation, such as CBC, CTR, GCM, and others, to cater to different security requirements and application scenarios. It can handle a large volume of data efficiently and securely.

Operation/Encryption process of AES

The operation of the Advanced Encryption Standard (AES) involves several key steps:

Advanced Encryption Standard (AES) - codingstreets
Source: AU
  1. Key Expansion: The AES algorithm starts with a key expansion process. The original key, which can be 128, 192, or 256 bits in length, is expanded to generate a set of round keys. These round keys are used in the subsequent encryption and decryption rounds.

  2. Initial Round: AES begins with an initial round where the input data, called the plaintext, is XORed with the first round key.

  3. Rounds: AES consists of several rounds, the number of which depends on the key size. For AES-128, there are 10 rounds; for AES-192, there are 12 rounds; and for AES-256, there are 14 rounds. Each round performs a series of transformations on the data.

  4. SubBytes Transformation: In each round, the bytes of the data are substituted with values from a substitution box (S-box). This non-linear substitution adds confusion to the data.

  5. ShiftRows Transformation: The bytes in each row of the data are shifted cyclically. This diffusion operation ensures that the output data is spread out and no longer aligned with the input.

  6. MixColumns Transformation: In this step, each column of the data is transformed using matrix multiplication. This operation further spreads and diffuses the data, providing additional security.

  7. AddRoundKey Transformation: At the end of each round, the data is XORed with a round key. The round key is derived from the original key during the key expansion phase.

  8. Final Round: The final round of AES excludes the MixColumns transformation. It performs the SubBytes, ShiftRows, and AddRoundKey transformations on the data.

  9. Output: After the final round, the resulting data is the ciphertext, which is the encrypted form of the original plaintext.


The decryption process in AES is essentially the reverse of the encryption process. The ciphertext is inputted, and the round keys are used in reverse order to obtain the original plaintext.

The operations of AES, including substitution, diffusion, and XOR operations with round keys, work together to provide a high level of security. AES is designed to be highly resistant to various cryptographic attacks and has been extensively analyzed and tested by the cryptographic community.


The article on the Advanced Encryption Standard (AES) provides a comprehensive overview of this widely adopted symmetric encryption algorithm. It highlights the key features, advantages, and operation of AES, making it an essential resource for understanding its role in securing sensitive data.

It emphasizes AES’s security, efficiency, and versatility. AES has been extensively analyzed and tested by the cryptographic community, demonstrating its resilience against various cryptographic attacks. Its support for multiple key sizes allows users to choose the appropriate level of security for their applications.

Overall, the article provides a comprehensive understanding of the Advanced Encryption Standard (AES), its strengths, and its significance in modern cryptography.

Recent Articles