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I'm looking for the homomorphic version of the following (I'm using Python here):

$ a = [1,2,3]
$ s = sum(a)  
$ print(s)
6

Is there an open source fully homomorphic library which is able to do $sum(vector)$? So far I just found libraries allowing operations with input-output either only vectorial or only integer. Here I'm asking for a vector to integer operation.

Of course there is another way, namely encrypting every integer element of $a$ individually, summing in the encrypted domain, and then decrypt the result. Since I would like to take advantage of the speed of vector batching, I'm not considering this as a good solution.

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    $\begingroup$ "I would like to take advantage of the speed of vector batching"; what is it about Paillier encrypting each individual element of the vector that makes 'vector batching' difficult? $\endgroup$ – poncho Oct 10 at 18:08
  • $\begingroup$ I'm not aware of libraries capable of quickly handling vectors of encrypted integers (instead of encrypted vectors of integers), but I'm happy to be proved wrong here. Also, I need fully homomorphic encryption, I will make this clear in the question. $\endgroup$ – Rexcirus Oct 10 at 18:40
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    $\begingroup$ I am not aware of schemes whose plaintext space is $\mathbb{Z}^n$ and that allow us to create ciphertexts encrypting values in $\mathbb{Z}$... But there are schemes that encrypt natively vectors and matrices and we can perform vector-matrix products. If you have several vectors $a_i$'s, you can put them in the columns of a matrix $A$, encrypt the vector $v = (1, 1, ..., 1)$, and do $v\cdot A$ to get $(sum(a_1), ..., sum(a_n))$. Well, it is already something... $\endgroup$ – Hilder Vitor Lima Pereira Oct 10 at 19:35
  • $\begingroup$ NTRU enables generic bit-sliced however, you need to find a way to combine the 2048 results. $\endgroup$ – kelalaka Oct 11 at 21:41
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As far as I know, there are many libraries that use lattices and LWE schemes to implement fully homomorphic Encryptions.

This is a set, Most of them is in C++ and Only one by MSFT is C#, But in all cases you can port the code to python aftor compiling:

  1. HElib in C++
  2. SEAL By MicroSoft C++/C#
  3. Palisade C++
  4. FHEW C/C++
  5. TFHE C++
  6. NFLib C++

Note: The set in no particular order.

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  • $\begingroup$ Did you see the Hilder's comment? The OP asking in $\mathbb{Z}^n$. OP doesn't ask for the list of libraries. $\endgroup$ – kelalaka Oct 11 at 17:42
  • $\begingroup$ Ok, You are right, my answer is irrelevant. but I think the original question needes updates. Any way KNN encryption scheme (not the classification) Allows multiplication of two encrypted values and the result is a vector. Is this what question you asks for ? $\endgroup$ – Walid Ashraf Oct 11 at 21:04
  • $\begingroup$ No, he just wants to add but wants to use parallelization. TheElGamal, Paillier may be enough for him, however, they have not vector to integer. $\endgroup$ – kelalaka Oct 11 at 21:10
  • $\begingroup$ Then his question can be solved using divide and conquer. The can split his data into multiple parts, each part is sent a processor then adds them... There are like a ton of methods to execute similar approaches? More importantly, I think he is asking in the wrong place !!! $\endgroup$ – Walid Ashraf Oct 11 at 21:34
  • $\begingroup$ Do you know the message size of 1-bit encryption? He is not looking for software way. AFAIK, NTRU enables generic bit-sliced. They run 2048 encryption altogether. $\endgroup$ – kelalaka Oct 11 at 21:42

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