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Homomorphic Encryption Library Supporting Addition, Multiplication & Logical Shift

pk flag
Sam

Does anyone know of a C++ homomorphic encryption library that supports addition, multiplication and logical right shift over integers? Some set of instructions that allows the implementation of logical shifts would work as well. The range should be at least sufficient to support signed 32-bit integers and the scheme should support arbitrary depth. I tried using Palisade, but found no way of implementing logical shift given the operations they provide without resorting to using a scheme that allows to pass a boolean circuit description.

Thank you in advance!

fgrieu avatar
ng flag
We normally do not allow questions asking for software recommendations, but I'll do if I had read the question as asking for an homomorphic encryption _method_ supporting addition, multiplication & logical shift. You should state if the coefficients for multiplication and shift count are public or not, things are much easier if they are. Also, perhaps, specify desired range and depth of expression. Notice that logical shift left is multiplication by a power of two. If reals or rationals are supported, that works for right shift with negative powers.
kelalaka avatar
in flag
Try the TFHE, the key is binary storage.
knaccc avatar
es flag
Can you elaborate on the use case? It might be enough to just construct your own very simple Pedersen commitments with an EC library.
fgrieu avatar
ng flag
Thinking aloud: an [ALU](https://en.wikipedia.org/wiki/Arithmetic_logic_unit) with 32-bit addition and multiplication (modulo $2^{32}$) and right shift can be built using relatively few gates (much less than a secure hash requires), and then these gates implemented with TFHE. Would that do?
kelalaka avatar
in flag
Shift was not [here](https://crypto.stackexchange.com/q/63781/18298) since it was free on binaries.
Sam avatar
pk flag
Sam
@fgrieur thank you for recommending using TFHE to solve this - I looked into it and it seems very promising; thank you also for the recommendations regarding my question itself
Sam avatar
pk flag
Sam
@kelalaka thank you for the suggestions of TFHE
Sam avatar
pk flag
Sam
@knaccc thank you for your suggestion - I will look into it
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