Scaling fully homomorphic encryption: current challenges and emerging solutions

Imagine being able to perform computations on encrypted data without ever needing to decrypt it. Fully Homomorphic Encryption (FHE) offers this groundbreaking capability, with enormous implications for privacy and security—whether in handling sensitive financial information, healthcare records, or confidential communications. However, like any revolutionary technology, FHE faces significant challenges, particularly when it comes to scaling for practical, real-world applications. In this article, we’ll explore the key hurdles FHE currently faces and the emerging solutions that are making it more viable for widespread use.

Computational overhead

One of the biggest roadblocks to scaling FHE is its computational overhead. FHE is notoriously resource-intensive, requiring far more processing power than traditional, non-encrypted computations. This computational burden becomes especially problematic in scenarios where speed is crucial, such as real-time data processing.

So, what’s being done about it? Researchers are making strides in reducing this overhead by developing novel algorithms and optimisations. Many of these advancements draw from lattice-based cryptography, which underpins most FHE schemes. Additionally, there’s promising work being done in leveraging machine learning to predict and optimise FHE performance, making it less of a computational monster. While we're not quite there yet, these innovations are crucial steps toward making FHE more practical for everyday use.

Limited depth of computations

Another challenge with FHE lies in the depth of computations it can handle. While fully homomorphic encryption allows for both addition and multiplication operations on encrypted data, it often struggles with more complex, multi-step computations. This limitation can severely restrict the kinds of tasks FHE can be used for, particularly in fields like artificial intelligence or deep learning.

But there’s hope on the horizon. Ongoing research is focused on creating FHE schemes that can support a broader range of computations without the significant overhead. A prime example is the TFHE (Torus Fully Homomorphic Encryption) scheme, which incorporates an efficient bootstrapping mechanism. This innovation has made it possible to evaluate deep neural networks using FHE, something that was previously unimaginable. As these techniques become more refined, the range of applications for FHE will undoubtedly expand.

Key management

In large-scale applications, securely generating, distributing, and managing encryption keys is a daunting task. If not handled correctly, poor key management can undermine the security that FHE is supposed to provide.

Emerging solutions like secure threshold decryption offer a promising approach to this challenge. In threshold decryption, the decryption key is split among multiple parties, and only when a certain threshold of parties agrees can the data be decrypted. For instance, with N/2 threshold decryption, at least half of the key holders need to collaborate to unlock the data. This method significantly reduces the risk of a single point of failure, making key management more robust and secure.

Data size inflation

One of the less talked about, but equally important challenges of FHE, is data size inflation. Encrypting data using FHE significantly increases its size, sometimes by orders of magnitude. This inflated data, known as ciphertext, can put a strain on both storage and network bandwidth, making FHE less practical for applications that involve large datasets.

Fortunately, researchers are working on solutions to minimise this inflation. By optimizing the mathematical structures and encoding techniques used in FHE, they aim to reduce the expansion factor of the ciphertext. These efforts are still in the early stages, but they hold promise for making encrypted data more manageable and easier to work with.

Hardware acceleration

Finally, as FHE moves toward practical implementation, there's growing interest in specialised hardware to speed up its operations. One exciting development is the use of silicon photonics, a technology that uses light instead of electricity to transmit data. This could drastically increase the speed and efficiency of FHE, while also reducing energy consumption.

Silicon photonics isn't just a theoretical solution; it's being actively explored as a way to overcome the current limitations of FHE. If successful, it could lead to the large-scale implementation of FHE, making it a viable option for a much broader range of applications.

Fully Homomorphic Encryption is poised to transform the future of secure computing. By allowing computations to be performed on encrypted data, it offers an unprecedented level of privacy and security. However, to realize its full potential, FHE must overcome significant challenges in computational overhead, depth of computations, key management, data size inflation, and processing speed.

The good news is that researchers are making steady progress in addressing these challenges. From algorithmic optimisations and efficient bootstrapping to secure key management and hardware acceleration, the solutions being developed today could soon make FHE scalable and practical for everyday use.

Ready to take your project to the next level? Get in touch with Source Control today and let us help you find the talent you need to scale your FHE initiatives and transform the future of secure computing.

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