Let's talk about AES-256
What is AES-256?
AES (Advanced Encryption Standard) is a symmetric encryption standard adopted by the National Institute of Standards and Technology (NIST) in 2001. This algorithm is based on block cipher, which means that it divides data into fixed blocks (128 bits) for encryption. The number 256 indicates the key length in bits used to protect the data.
AES is part of the FIPS (Federal Information Processing Standards) standard and is used by governments, financial institutions and military-grade security systems because of its robustness.
How does AES-256 work?
AES operates on 128-bit blocks and encrypts data in several rounds of transformation. The number of rounds varies depending on the length of the key:
AES-128 → 10 rounds
AES-192 → 12 rounds
AES-256 → 14 rounds
In AES-256, the main steps in each round are:
- SubBytes (Substitution):
Each byte of the data block is replaced by a value obtained from a substitution table known as S-Box.
This introduces confusion (the encrypted data is not related to the original).
- ShiftRows:
The bytes in each row of the data matrix are shifted a specified number of positions.
This creates diffusion, scattering the original data throughout the block.
- MixColumns (Mix):
The columns of the block are transformed by mathematical calculations (operations on the Galois field).
It increases the diffusion and causes small changes in the original data to significantly affect the encrypted result.
- AddRoundKey:
An XOR operation is applied between the data block and a subkey derived from the master key.
This binds the encryption to the key and protects against attacks.
- Key expansion:
The original 256-bit key is expanded to generate a subkey for each of the 14 rounds.
Advantages of AES-256
- High security:
AES-256 offers a gigantic key space (2^256 possible combinations), making it virtually impossible to crack by brute force.
- Efficiency:
Despite its robustness, AES-256 is efficient and fast, so it can be implemented in hardware and software.
- Global standard:
It is used in HTTPS, VPNs, banking applications, cloud storage and military-grade cybersecurity systems.
- Attack protection:
AES-256 resists advanced attacks such as differential, linear and known plaintext cryptanalysis.
Where is AES-256 used?
Secure data transmission over the Internet: HTTPS and SSL/TLS protocols.
File protection: Tools such as BitLocker, VeraCrypt or ZIP use AES-256 to encrypt data.
VPN and private networks: Remote communications security.
Cloud storage: Google, Microsoft and AWS use it to protect data.
Enterprise cybersecurity: Systems to protect databases, passwords and sensitive files.
Although precise statistics are not available to indicate the percentage of AES-256 use in each sector, it is possible to highlight its application in several areas:
Government and Defense: Government entities, such as the U.S. National Security Agency (NSA), employ AES-256 to protect classified information.
Financial Services: Banking and financial institutions use AES-256 to secure transactions and customer data, ensuring the confidentiality and integrity of information.
Healthcare: The healthcare sector implements AES-256 to protect electronic medical records and comply with privacy regulations, ensuring that patient information remains confidential.
Technology and Communications: Technology and telecommunications companies integrate AES-256 into mobile applications, cloud storage services and wireless communications to safeguard data against unauthorized access.
E-Commerce: E-commerce platforms employ AES-256 to protect customers' payment information and personal data during online transactions.
Why is it so secure?
AES-256 is considered secure even against attacks with quantum computers due to the length of the key. Although post-quantum cryptography is still under debate, AES-256 offers a robustness that is very difficult to crack in today's world.
AES-256 encrypts information in 128-bit blocks using 14 rounds of transformation, generating encrypted data that is virtually impossible to decrypt without the correct key. It is a key pillar of modern cybersecurity.
Although the adoption of AES-256 is widespread, the choice of this encryption standard may vary depending on the specific security needs, applicable regulations and internal policies of each organization.
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