Request for Homomorphic Comparison of Two Cipher Texts Sample Code

[PavanNPatil17]

Hello everyone,

I am currently working on a project that requires me to perform homomorphic comparison of two cipher texts. I have been searching for sample code that can help me understand the implementation of this process, but I haven't found anything useful yet.

I would like to request anyone who has worked on a similar project or has knowledge in this field to kindly share some sample code or resources that could help me with this task. I am particularly interested in code examples using homomorphic encryption schemes or fully homomorphic encryption (FHE).

Any help would be greatly appreciated, and I believe that it will not only help me but also benefit other researchers who are working on similar projects.

Thank you in advance for your support.

Best regards,
Pavan N Patil

[Pro7ech]

Hi @PavanNPatil17,

High accuracy homomorphic comparison is a planned feature for Lattigo. This will include the work of Lee et al.. However there is still quite some work to finish before we can integrate this into the library.

In the mean time, I can provide you with a sample of composite polynomials computed using the work of Lee et al. They allow to approximate the sign function in the interval [-1, 2^-a] U [2^-a, 1] for 1 <= a <= 30.

Using the sign function you can implement a multiplexer gate MUX(a, b, sign(a, b)) -> (min(a, b), max(a, b)) that will sort two values. This can be used as a building block for larger sorting (e.g. as in the work of Hong et al.).

Beware that such operation is expensive and will require multiple bootstrappings per comparison.

Hope this help :)