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Questions tagged [homomorphic-encryption]

Cryptosystems which support computation on encrypted data. They might be partially homomorphic (support for one operation such as + or *) or they might be fully homomorphic (any sequence of + and *).

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32 views

Key derivation scheme with shared secrets?

I want to derive a list of sub-keys derived[t] from a master key mk by a key derivation function ...
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1answer
35 views

Retrieving correct ciphertext from additive ElGamal

I have been studying additive ElGamal and I think I have the hang of it except the part where the message $M$ must be retrieved by computing the discrete log of $g^M$. From what I've read, the ...
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1answer
63 views

Is there a cryptosystem which allows slicing and concatenating strings without decryption?

I want a cryptosystem with the following four functions: ...
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38 views

One-way Functions for Floating Points

Are there any commutative one-way functions for floating points? I tried to explain why I need these functions. First, I describe the problem on a high level and then I further formalize it; There ...
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1answer
48 views

Sum vector elements homorphically

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 ...
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34 views

Reference for the Security Analysis of Ring-LWE

Can someone please share a link of any research paper or web-page analyzing the security of Ring-LWE? Essentially, how should I choose my parameters to get security equivalent to 128-bit or 256-bit?
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Homomorphic Public/Private Key Encryption Scheme for Floating Numbers

Is there any public/private homomorphic encryption scheme that directly works on floating numbers or vectors of floating numbers? In our application, we want to find out if $$v_1 \approx v_2, \qquad\...
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31 views

Is it possible to sample HE ciphertexts using pseudo-random generator?

I'm trying to sample HE ciphertexts which serve as ciphertexts encrypting some random values. I have realized a example program using Microsoft SEAL, which implements a variant of BFV scheme. ...
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42 views

Hash function over numbers that preserve addition and multiplication

I wonder if there is a known hash function that for any $x$, $y$ which are numbers in a certain range with certain accuracy (I guess one can think of them as integers?), you can define two functions ...
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80 views

Can homomorphic encryption be used to exchange keys?

Fully Homomorphic Encryption (FHE) allows computations be done on ciphertexts. Can this technique be used to exchange keys? For example, Alice and Bob need to agree on a 4-bit secret key. Alice sends ...
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44 views

Why is the Paillier cryptosystem not considered fully homomorphic encryption? [duplicate]

Paillier is an additive homomorphic encryption system that can achieve the encrypted version of its sums. However, we can calculate the encrypted version of their multiplications by raising an ...
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Is there a standard benchmark data set for “Homomorphic Encryption” implementations?

Both in terms of statistical analysis (mean/variance, histograms, contingency tables, etc) and machine learning data sets. The question has also been asked here.
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Why is the Domingo-Ferrer cryptosystem not used in practice?

The Domingo-Ferrer cryptosystem is a fully homomorphic cryptosystem. It works fast enough. I have only seen known-plaintext attacks. Is this a reason not to use it in practice? Or are there more ...
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Are biases narrowed towards the provenance of hard NP complete problems relevant?

I hear of randomized reduction, deterministic reduction and non-deterministic reduction of complexity from A to B problems. This could make things impossible for polynomial time adversary prying into ...
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Do I need to use a matrix of size N x n for the public key in the BGV scheme when using Ring-LWE?

I'm going through the BGV paper and trying to make a toy implementation, but I just want to focus on Ring-LWE. In the paper, they set $N = \lceil{(2n + 1)\log_2(q)\rceil}$, and generate $A'$ uniformly ...
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Maintaining validity of ZKP throughout re-randomization of homomorphic ciphertext without linkability to previous ciphertext

Question: How is it possible to adapt a ZKP for a homomorphic ciphertext to still be valid after said ciphertext has been re-randomized? Context: In a lot of e-voting systems homomorphic encryption ...
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Compute ln function of a Paillier encrypted value [closed]

If I have an encrypted value $Enc(x)$ with Paillier cryptosystem, is it feasible to compute an encryption form of $\ln(x)$ or its approximation using homomorphic properties? The input $x$ is always ...
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47 views

BGV for three multiplication level/depth

Can BGV homomorphic encryption scheme support three multiplication level/depth with the help of key switching and modulus switching? If Yes, how does one set up the parameter to achieve that?
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homomorphic encryption function representation

As it known, Homomorphic encryption can be used for privacy-preserving outsourced storage and computation. In various constructions, the computations are represented as either Boolean or arithmetic ...
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1answer
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Why FHE only needs support for addition and multiplication

For example, given $E(m_1)$ and $E(m_2)$ to the cloud. How does it calculate $E(m{_1}^{m_2})$? Is it related to the claim that any computable function can be represented as a circuit containing or <...
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What is Homomorphic encryption evaluation key

In some homomorphic encryption schemes (e.g Multi-key fully homomorphic encryption report, Computing Blindfolded: New Developments in Fully Homomorphic Encryption), it defines an encryption key, a ...
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56 views

What is labeled program

I've been studying homomorphic encryption. From their instantiations, i read Labeled Homomorphic Encryption (labHE) scheme 1 where it combines the notion of homomorphic encryption with labeled ...
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Implementation of addition in the scheme TFHE

I want to implement the addition operation in a fully homomorphic scheme - TFHE. It contains homomorphic operations on bits: AND, OR, NOT, XOR. Found addition algorithms include left and right shift. ...
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An example of calculation of BGV encryption

Can anyone give an example RLWE BGV encryption with numbers? like where m=8 (ring dimension), q=ciphertext modulus = 33=3*11 with level=2 What are COEFFICIENT and EVALUATION representation ?
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Can someone explain Relinearisation process in FV scheme for Homomorphic Encryption?

I am trying to understand the relinearisation process in FV scheme for Homomorphic Encryption based on R-LWE. Can one someone explain how the homomorphism keys are generated? I have worked out an ...
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How to solve a simple case of a RLWE problem

I've been reading up on the Ring Learning with Errors problem and the proposed attacks, in relation to homomorphic encryption. Some of the literature has been quite difficult to understand - what I ...
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FHE: What is the difference between multiplicative depth and multiplicative level?

I have seen the terms multiplicative depth and multiplicative level while reading Faster homomorphic encryption is not enough: improved heuristic for multiplicative depth minimization of Boolean ...
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What is the main purpose of using Boolean Circuit Model in Homomorphic Encryption?

Why do we use or have Boolean Circuit Model is it because since it uses gates and bits we could adapt it into a hardware model?
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60 views

Is there any relationship between Paillier Cryptosystem's random r and other factors

I want to try run an example of Paillier cryptosystem(Algorithm), So i just started with some basic examples, but cannot obtain correct result/decryption. I just change random factor ...
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1answer
104 views

Where does bootstrapping occur, client side or server side?

In Fully Homomorphic Encryption, where does the bootstrapping procedure performed, in the client-side or the server-side? Also, which side holds the secret key and the public key?
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What are the advantages of using Leveled Homomorphic Encryption over Somewhat Homomorphic Encryption?

Is there a point in using LHE over SHE? From what I understand, SHE is like an extended version of LHE, the only difference is that you limit the depth of circuits that can be evaluated. Therefore, I ...
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How to compute the inner product on encrypted vector by using a third party?

I want to compute the inner product of two vectors on a third party, i.e. $f(x) \cdot f(y) = x \cdot y$ where $x$ and $y$ are two vectors. However, I do not want the third party knows the real value ...
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1answer
48 views

How re-encryption can be done through RSA

Both RSA and Elgamal have homomorphic properties. So both can re-encrypt the ciphertext. Re-encryption with Elgamal works as seen here. How does re-encryption work using RSA? What modification / ...
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Are there any advantages and disadvantages with what type of model of homomorphic computation is used? [closed]

I am curious about the advantage or disadvantage in using the different models of homomorphic computation (boolean circuits, modular arithmetic, approximate number arithmetic). Are there any specific ...
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1answer
59 views

How to implement GSW13 using Helib or SEAL?

I want to implement the homomorphic encryption scheme proposed in GSW13, and make some changes to it, but seems that there is no library that has already been implemented it. Since this is a ...
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1answer
59 views

Do Partially Homomorphic Encryption schemes also suffer from noise overflow?

Do PHE schemes in general also suffer from noise overflow problem?
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1answer
118 views

Classification of BFV and CKKS scheme?

I would just like to ask what is the classification of both BFV and CKKS scheme are they Somewhat Homomorphic or Fully Homomorphic? Brakerski/Fan-Vercauteren (BFV) [Brakerski12, FV12, BEHZ16, HPS18] ...
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In using Boolean Circuits model of Computation in Homomorphic Encryption why is is considered fast?

I am currently doing some reading on Homomorphic Encryption for research purposes and based on my reading using the Boolean Circuit Model of Computation specifically in regards to Fast Fully ...
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1answer
61 views

Are there any symmetric Partial Homomorphic Encryption Schemes?

Note that I am asking specifically for Partial Homomorphic Encryption (PHE) schemes and not Somewhat Homomorphic Encryption (SHE) schemes. I believe there are several SHE schemes that are symmetric ...
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109 views

Is there FHE (fully homomorphic encrpytion) for string/text processing?

I had a quick look at FHE libraries like SEAL, HeLib, and Palisade and they deal with addition or multiplication of encrypted data. Is there a FHE that deals with string? If no, is that because it is ...
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Simple explanation of CKKS scheme

I'm searching for a (preferably simple) explanation of the Cheon-Kim-Kim-Song scheme for fully homomorphic encryption. All I did find so far is the original paper, which is rather difficult to ...
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1answer
129 views

How exactly is TFHE secure?

TFHE (Fully Homomorphic Encryption over Torus) seems to be a state-of-the-art form of homomorphic encryption. But, I got a bit confused. I have recently read the paper Fully Homomorphic Encryption ...
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Is it possible to enhance white-box cryptography security by homomorphic encryption?

Background: Let's discussed based on published symmetric white-box crypto only, such as Chow's white-box AES. I only know basic concepts/objectives of homomorphic encryption, such as PHE and FHE. ...
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1answer
78 views

Can the person who decrypts a homomorphically encrypted value know what operations were run?

I'm looking at the SEAL library but I'm trying to figure out what happens in a certain use case. For example: Alice encrypts the number 123456 homomorphically and sends it to Bob. Bob adds 25 and ...
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Whether ramp secret sharing possess additive homomorphism?

Ramp secret sharing replaces the random coefficients in original Shamir secret sharing with original data to be shared. In such a case, all the coefficients in the polynomial evaluation will be ...
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Secure Computation with TTP using Ring-LWE Homomorphic Encryption

I was working with secure outsourced computation for multi-party computation in which security is assured by ring-LWE based asymmetric homomorphic encryption in the semi-honest model. Is it feasible ...
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68 views

How can I prove that the plaintext of an elgamal ciphertext is the discrete log of an element?

Is there any (efficient) method to prove that the plaintext of an ElGamal ciphertext is the discrete log of an element? In the scenario I concerned, I have an El Gamal key pair $(pk, sk) = (g^y, y)$....
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1answer
48 views

Comparison of values in Paillier homomorphic encryption

For a project, I am using homomorphic encryption with the Paillier cryptosystem, and I have to compare two values... Can this be done using homomorphic encryption? And I know subtraction can be done ...
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1answer
59 views

Is it possible to change the generator without knowing the private key used?

For example, prover sends P = xG and verifier somehow sends back P = xH without learning x. Is this possible?
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Gentry-Halevi’s Fully-Homomorphic Encryption and hermite factor

In section 7.2, page 18 in Chen-Nguyen paper regarding BKZ 2.0, they point out different Hermite factors related to Gentry-Halevi FHE. More precisely, it is said that the critical Hermite factor for ...