AES Encryption Algorithm | AES Full Form and Working Explained

AES encryption, established by the National Institute of Standards and Technology (NIST) in 2001, is a symmetric block cipher known for its strength, speed, and efficiency. Designed to replace the outdated Data Encryption Standard (DES), AES supports key sizes of 128, 192, and 256 bits, offering robust protection. 

Today, AES secures an estimated 80% of global encrypted internet traffic, and it is foundational in technologies ranging from VPNs and Wi-Fi networks (WPA2/WPA3) to cloud storage, online banking, and government communications.

In this article, we have explained the AES encryption algorithm, covering the full form, meaning, working, advantages, and disadvantages. We have also compared AES to its competitor, RSA, to understand why AES is popular.

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What is AES?  

AES stands for Advanced Encryption Standard. It is a symmetric encryption algorithm used to securely convert data into an unreadable format using 128, 192, or 256-bit keys. A symmetric block cipher means that it takes 128 bits of input and produces a 128-bit ciphertext. 

It uses a substitution-permutation network, performing multiple rounds of data substitution and shuffling to ensure high-level security. AES depends on the substitution-permutation network principle, which works by using a series of linked operations that involve replacing and shuffling the input data.

Features of AES  

The following are the main features: 

● AES is a symmetric-key block cipher that processes data in fixed 128-bit blocks.  

● It supports key sizes of 128, 192, and 256 bits, with 10, 12, and 14 encryption rounds, respectively.  

 ● AES provides high security against brute-force and cryptanalytic attacks and is NSA-approved for protecting top-secret information 

●  It is highly efficient in both hardware and software, especially with AES-NI acceleration, and uses key expansion to generate secure round keys. 

 ● Standardized by NIST under FIPS 197, AES is globally adopted in protocols like TLS, VPNs, Wi-Fi, and disk encryption. 

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How AES Works?

AES operates using three key sizes, each defining the number of rounds used in the encryption process: 

● AES-128 uses a 128-bit key and performs 10 rounds of encryption. 

● AES-192 uses a 192-bit key with 12 rounds. 

● AES-256 uses a 256-bit key and goes through 14 rounds. 

Each of these versions encrypts and decrypts 128-bit blocks of data. As the key length increases, so does the number of encryption rounds, making the cipher more secure and harder to break through brute-force or cryptanalysis. 

In AES, the input data (plaintext) is first arranged into a 4x4 matrix of bytes, called the state. The encryption process then applies a series of transformations in each round to scramble this data: 

1. SubBytes: Each byte is replaced using a predefined substitution box (S-box) to introduce non-linearity. 

2. ShiftRows: Rows in the matrix are shifted left by different offsets to increase diffusion. 

3. MixColumns: Each column is mathematically transformed to further mix the data (this step is skipped in the final round). 

4. AddRoundKey: A unique round key (derived from the original encryption key) is combined with the data using a bitwise XOR operation. 

These steps are repeated for the total number of rounds based on the key size. The more rounds, the more secure the encryption. 

During decryption, the recipient uses the same key and performs the inverse operations in reverse order to reconstruct the original plaintext from the ciphertext. This process ensures that even if someone intercepts the encrypted data, they cannot read it without the correct key.

How AES Ensures Data Security? 

AES is trusted worldwide for securing everything from classified government data to online financial transactions and cloud storage. 

AES can be used in secure modes like Galois/Counter Mode (GCM) and Counter Mode (CTR), which enhance performance and security. GCM ensures both encryption and authentication, while CTR enables high-speed, real-time encryption. These modes use unique initialization vectors to prevent replay attacks, making AES suitable for encrypting dynamic data streams securely and efficiently. 

Applications of AES in Cybersecurity 

The following are the main applications of AES: 

● Hard drives and SSDs automatically encrypt and decrypt data using AES without performance loss, enhancing laptop and enterprise storage security. 

● Cloud and local backup solutions (like Veeam, Acronis) use AES to encrypt backup archives, ensuring disaster recovery data remains confidential. 

● Embedded systems (medical devices, automobiles, drones) use AES to verify and decrypt firmware updates, preventing tampering or hacking. 

● Streaming platforms and eBook publishers use AES encryption to control access and prevent piracy of digital content. 

● Specialized devices that securely manage, store, and process encryption keys often use AES for protecting sensitive operations internally. 

● AES is integrated into TPM hardware to secure hardware-level authentication, encryption, and platform integrity checks. 

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AES vs RSA 

Here’s a table comparing AES vs RSA: 

Advantages Of AES 

The following are the advantages of AES 

● AES is considered highly secure and resistant to known cryptographic attacks, including brute-force attacks. 

 ● AES is fast and efficient, particularly when accelerated with AES-NI (hardware support), making it suitable for real-time applications. 

● AES supports key sizes of 128, 192, and 256 bits, offering flexible security levels for various applications. 

●  It is widely used across industries like finance, healthcare, and government, ensuring compatibility and trust. 

Disadvantages Of AES 

The following are the disadvantages of AES 

● Securely managing and distributing AES keys can be challenging, especially in large systems. 

● While AES itself is secure, implementations can be vulnerable to side-channel attacks (e.g., timing attacks). 

● AES is a symmetric algorithm, requiring the secure sharing of keys between the sender and receiver. 

● While AES is efficient, it requires hardware support (e.g., AES-NI) to achieve its full performance potential. 

Future of AES and Its Role in Encryption Advancements 

The Advanced Encryption Standard (AES) continues to play a critical role in global data security, evolving alongside new technologies and threats. AES-256 is recognized for its quantum resistance, with NIST 2024 guidelines promoting hybrid systems combining AES-256 with post-quantum algorithms like CRYSTALS-Kyber. 

By 2025, 70% of enterprises plan to adopt AES-256, driven by compliance and quantum readiness, according to Forrester. Despite challenges like side-channel attacks, innovations such as lightweight AES variants are enhancing security for low-power devices. 

Conclusion 

The Advanced Encryption Standard (AES) has set the benchmark for secure, fast, and reliable encryption worldwide. Its robustness, flexibility, and broad adoption make it a cornerstone of modern cybersecurity.

Whether protecting sensitive personal data or safeguarding critical national infrastructure, AES plays an essential role in keeping information secure in our increasingly connected world.