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The future of encryption: AES-256 and CRYSTALS-Kyber in the age of quantum computers

The future of encryption: AES-256 and CRYSTALS-Kyber in the age of quantum computers
April 12, 2024

The development of quantum computers represents a revolutionary change in computing power that has the potential to shake the foundations of current encryption standards. In this context, two encryption algorithms, AES-256 and CRYSTALS-Kyber, are coming into the spotlight as answers to the challenges of the post-quantum era.

AES-256: The standard for symmetric encryption

AES-256, the Advanced Encryption Standard with a 256-bit key, has long been the gold standard for symmetric encryption and provides a high level of security for a wide range of digital applications. From the secure transmission of sensitive government documents to protecting private communications in social networks, AES-256 forms the backbone of modern data encryption. Its strength lies in the simplicity of its implementation and the complexity it presents to attackers attempting to crack the encryption key through brute force attacks.

Advanced functionality of AES-256
Advanced Encryption Standard (AES) encryption is a widely used cryptographic system known for its security and efficiency. AES operates with data blocks of 128 bits and uses keys of lengths 128, 192, or 256 bits for encryption. AES-256, which uses the most extended key, offers the highest level of security of the standard AES formats. The choice of a longer key increases the complexity for potential attackers exponentially and makes cracking the encryption practically impossible with current and foreseeable technological means.
The AES-256 encryption process involves multiple passes or "rounds" of data manipulation involving a combination of substitution, permutation, and mix operations. These processes transform plaintext into ciphertext through a highly structured series of steps, each of which contributes to the overall process's security. Each round uses a portion of the key, and the entire process provides a strong mixing of the data, making decryption without the exact key extremely difficult.

Extended AES with 512 bits from Protectstar
In addition to the standardized key lengths of AES, Protectstar has developed an extended version of AES, the Extended AES (, with a key length of 512 bits.
This innovation aims to increase security by lengthening the key, which, in theory, further increases resistance to brute force attacks. It is important to note that such extensions go beyond the standardized specifications of AES and require specific implementations that should be carefully tested and evaluated to ensure their security in different application contexts.

The introduction of a 512-bit key in the Extended AES version follows the logic that doubling the key length means a quadratic increase in the possible key combinations, significantly increasing the theoretical security. This is particularly important in a future where computing power continues to grow exponentially and the development of quantum computers threatens existing encryption mechanisms.

While standard AES already provides a robust security solution, the development of Extended AES underlines the ongoing search for even stronger encryption methods to protect sensitive data from future threats. However, caution must be exercised when evaluating such extended systems, as compatibility with existing standards and practical implementation security are critical factors that must be considered.

Simply explained:
The difference between conventional computers and quantum computers
Imagine you have a massive mountain of Lego bricks, and your task is to find out if there is a specific combination of bricks that can build an exceptional house together. If you were using a conventional computer, it would take each brick and check if it fits, one by one, until it finds the right combination. That can take quite a long time, especially if there are many bricks.

On the other hand, a quantum computer would be like having a magical ability that allows you to lift and check many bricks at once to find out much faster if they can work together to build the house you're looking for. That's because quantum computers use a special kind of math that allows them to explore many possibilities simultaneously rather than going step by step.
Conventional computers work with what we call "bits." A bit is a small box that is either empty or full—it can hold either a 0 or a 1. All the information in your computer, from the games you play to the homework you write, is represented with these 0s and 1s.

Quantum computers use something we call "qubits". Think of a qubit as a magic ball that can be not only empty or full, but also somewhere in between - it can be a little bit 0 and a little bit 1 at the same time. That sounds crazy, doesn't it? But that's exactly what makes quantum computers so powerful. They can process information in a way that conventional computers can't, by performing many tasks simultaneously.

What does this mean for encryption?
Let's think about how we securely encrypt messages. It means that a quantum computer could solve very complex puzzles that we use to secure our secrets much faster than a conventional computer. It's like suddenly having a map in a treasure hunt that shows all the places where the treasure might be simultaneously instead of having to investigate each place individually.

The challenge of quantum computers

Quantum computers use the principles of quantum mechanics to process information, which theoretically gives them the ability to solve certain problems much faster than classical computers. This includes the ability to crack the cryptographic algorithms on which many of today's encryption standards are based. In particular, asymmetric cryptosystems, such as RSA and ECC, are vulnerable to quantum algorithms such as Shor's, which could break these systems in polynomial time.

AES-256 in the quantum era

Although AES-256 is considered more resistant to quantum attacks compared to asymmetric methods, Grover's algorithm, a quantum algorithm, could significantly reduce the time needed to crack or break AES-256.
This means that AES-256, although potentially vulnerable, still offers a high level of security against quantum attacks, especially considering that the practical implementation of Grover's algorithm on a scalable quantum computer still seems a long way off.

CRYSTALS-Kyber: The answer to the quantum threat

CRYSTALS-Kyber represents the next generation of encryption technology, specifically designed to address the challenges posed by the development of quantum computers. As one of the leading candidates in the NIST process to standardize post-quantum secure cryptographic algorithms, Kyber offers a promising solution for the security of digital communications shortly.

How CRYSTALS-Kyber works
CRYSTALS-Kyber is based on the principle of learning parity with noise, an approach that has proven resilient to quantum computing attacks. Unlike traditional asymmetric encryption methods, which are based on factoring large numbers or calculating discrete logarithms, Kyber relies on mathematical problems that are difficult to solve even for quantum computers.

The choice between AES-256 and CRYSTALS-Kyber

The decision of whether to use AES-256 or CRYSTALS-Kyber for encryption depends on several factors, including the specific security requirements of the application, the expected lifetime of the information to be protected and the infrastructure available to implement these technologies. While AES-256 currently provides a high level of security and is widely implemented, CRYSTALS-Kyber represents a future-proof option specifically designed to address the challenges posed by quantum computing.

The "noise"
The "noise" in cryptographic contexts, especially in the "learning parity with noise" (LPN) approach, refers to a deliberate introduction of errors or irregularities in the data to increase the security of an encryption system. In cryptography, this concept is used to make the task of learning a secret key from transmitted messages considerably more difficult.

Basic concept of learning parity with noise (LPN)

To better understand the principle, imagine you have a set of linear equations that you want to solve in order to obtain certain information. Normally, this would be a straightforward math problem. However, when "noise" is added, it means that some of the equations intentionally contain incorrect or misleading information. The goal is to still find the correct solution despite the fact that some data has been manipulated. This manipulation of the data makes it much more difficult to find the solution, especially for someone who does not have the right "key" or algorithm to interpret or ignore the noise.

How does this work in cryptography?
A similar methodology is used in cryptography. A simple example of LPN might involve transmitting binary data (1s and 0s), intentionally introducing errors in a certain percentage of the data. Knowing the correct algorithm and secret key, a legitimate recipient could correct these errors and decrypt the original message. However, an attacker attempting to decrypt the message without knowledge of the key would face the enormous challenge of distinguishing the intentionally introduced errors from the actual data.

Noise as a security feature
The "noise" thus serves as a kind of protective layer that increases the security of the encryption process by increasing the complexity for unauthorized decryption attempts. This makes algorithms based on the LPN problem particularly attractive for the development of post-quantum encryption methods such as CRYSTALS-Kyber. The key to security is that while it is feasible for the authorized user with the correct key to "clean up" the noise and reveal the original message, it is virtually impossible for an attacker without that key to do so, especially considering the potential capabilities of a quantum computer.
The "noise" in cryptography is not a disturbance or an undesirable element but rather a deliberately introduced component that increases the security and resilience of an encryption system. It is a sophisticated means of ensuring the privacy and integrity of data in an increasingly digitalized world and potentially threatened by quantum computing.


Cryptography is on the threshold of a new era characterized by the rapid development of quantum computing technology. AES-256 remains a robust standard for symmetric encryption, but the emergence of quantum computing requires new approaches to data security. CRYSTALS-Kyber, as part of a new wave of post-quantum secure algorithms, offers a promising perspective for securing digital information against the quantum threat. As the cryptography community continues to develop and evaluate these technologies, it remains critical that organizations and individuals recognize and implement the importance of encryption and the need to keep pace with the latest security standards. In the ever-changing digital security landscape, it is paramount to remain proactive and prepare for future challenges.

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