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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How to backup a secret encrypted by multi parties without revealing the secret?

I'm searching for a way to backup a secret that only the end user knows the information with 2 trusted hosts. But trusted hosts shouldn't have access to secret at any time. First basic version : ...
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Fully homomorphic encryption (over addition and multiplication) library in python

I was wondering if there is a commonly used library in Python (or another common language such as Java, C++, etc.) for fully homomorphic encryption over multiplication and addition that also supports ...
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Whether there is a public key encryption system based on elliptic curve with the property of multiplication and addition homomorphism。

I want to implement it on the intelligent contract and then do the development,because use paillier i cant genereate 1024bits key,so i try to find if there is exit a public key encryption system based ...
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Zk-SNARK against Sigma Protocols and for Secure Function Evaluation

I have a couple of questions on ZK-SNARK: Based on what I understand, a ZK-SNARK is an "Argument of knowledge". That means that it should be equivalent to Sigma Protocols like Fiat-Shamir and ...
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Identify and exclude extremes while calculating mean using homomorphic encryption

Is it possible to identify extremes for a given set of values using homomorphic encryption? The goal is to exclude those extremes from a calculation for the arithmetic mean. E.g. [1,3,5,7,110] = ...
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Noise budget stops decreasing further, while running simple additions

I'm experimenting with Microsoft SEAL 3.4.5. I've a simple addition, which I run within a for-loop. ...
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Confidential data encryption on ethereum

I already built a supply chain that is able to collect product information on Ethereum. Now, that data can be confidential, but I still want to do Matrix calculations on it. I came across homomorphic ...
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Google Timeline: is it encrypted and if so who has the key? [closed]

Google Timeline claims (e.g. here) that "Your Timeline is private, so only you can see it." What does that mean? As a cryptographer I would take that to mean that the Timeline data is encrypted using ...
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Is it possible using homomorphic encryption (or some other technique)

Is the following possible with homomorphic encryption (or some other technique)? Suppose the cloud server keeps a key-value list for a user with each value field encrypted (prv key with user). Now, ...
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Fully Homomorphic cryptographic Scheme?

Given two FHE schemes FHE1 and FHE2 in which one of the two scheme is secure and other is not (we have no idea which is secure). Construct a FHE scheme which is secure using the given two scheme.
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How to implement division operation on ciphertext by using HElib or SEAL?

HElib has no general purpose API for number operations such as comparison or division. How can we implement division operation on ciphertext?How to encrypt floating numbers of any length in ...
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Decryption in Goldwasser-Micali Scheme

Referring to the following URL: http://cryptowiki.net/index.php?title=Goldwasser_Micali_cryptosystem The decryption of the message is based on wether the bit is a QRn or not, but how do we know/...
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LSIM library based on LibScarab

In a book called: "Intelligent,Secure and Dependable Systems in Distributed and Cloud Systems" where we can find some of its pages on the following URL: https://books.google.com.lb/books?id=...
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How to combine homomorphic encryption with secure multi-party computing?

I admit that I am a novice in cryptography, and I temporarily received a project that requires the use of homomorphic encryption technology and secure multiparty computing technology. Our team plans ...
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Bubble sort in Fully Homomorphic Encryption [duplicate]

I've read in a pdf written by Ayantika Chatterjee and Khin Mi Mi Aung whose title is "Fully Homomorphic Encryption in Real World Applications" that it is possible to implement a bubble sort algorithm ...
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Bootstrapping vs Recryption

In the context of fully homomorphic encryption, what is the difference between bootstrapping and recryption, since both offer the same result which is trying to eliminate/decrease the noise budget. ...
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What's the deal with conditional and jump operations in homomorphic encryption?

I'm doing some research about full homomorphic encryption (FHE). As I figured out, algorithms are implemented in circuits. I suppose that they are called circuits because the Holy Grail is to realize ...
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Homomorphic Encryption Verification

How much is it possibile to devide $E(m_1+m_2)$ by $E (m_1)$ to obtain $E (m_2)$ based on the fully Homomorphic-encryption property which says; $$E (m_1) * E (m_2) = E (m_1 + m_2)$$. And if yes what ...
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How do I prove that a user encrypted the data?

I am using homomorphic encryption, and I need to check whether or not a user's data is actually encrypted. For example, an eCommerce website pulls data from a user called Alice and wants to prove to ...
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Vector dot product in Microsoft SEAL using the CKKS scheme

I'm trying to use the Microsoft SEAL library in order to do Matrix multiplication. That's why I'm trying to find a way to compute the Dot Product of 2 vectors. My issue is that the CKKS encoder in ...
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Does Goldwasser-Micali only encrypts only 1-bit or multiple?

I've read online that the Goldwasser-Micali scheme can only encrypt 1-bit then I read that in another pdf that that scheme can encrypt a message of multiple bits so I'm confused. Can anyone clarify ...
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how to get top 10 numbers after using Pallier cryptosystem

Assume I encrypted 1000 Integers using the pallier cryptosystem. Since each time I encrypt a number using pallier I'm using a random ...
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Advantages of Pallier vs Goldwasser-Micali

It is easy to see that both Pallier and Goldwasser-Micali are homomorphic addition schemes and are secure but what would be the advantages of choosing one over the other?
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Is it possible to derive a homomorphic signature from homomorphic encryption

At the moment I am trying to find a practical way to implement a linearly homomorphic signature. Background: "In a homomorphic signature scheme, a user Alice signs some large dataset x using her ...
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How does Flatten really make the coefficients of a vector matrix small in LWE

In Homomorphic Encryption from Learning with Errors: Conceptually-Simpler, Asymptotically-Faster, Attribute-Based, Gentry et. al defined Flattening as follows; Let $\vec{a},\vec{b}$ be vectors of ...
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Homomorphic Encryption Roadmap

I'm looking for some suggestions on what to read (papers, notes, book chapters?) on homomorphic encryption in order to understand the most recent (more optimal) schemes, as well as optimized use cases ...
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Threshold decryption in multi-key homomorphic encryption

I have a problem understanding the security of threshold decryption in multi-key homomorphic encryption (MKHE) with so called "noise flooding". In particular I think that it is not secure, so probably ...
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Fully Homomorphic Encryption - state of the art

What are the latest advances in fully homomorphic encryption? First of all, I am interested in cryptosystems based on LWE / RLWE and NTRU problems.
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Security of somewhat homomorphic encryption via LSB encoding?

I'm reading this paper https://eprint.iacr.org/2011/344.pdf It says that "The secret-key encryption scheme whose security is based on the LWE assumption is rather straightforward. To encrypt a bit, $...
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Proving the right encrypted message was sent

Total amateur to crypto here but I've searched and searched and am at the extent of my knowledge. I've gone down several avenues to satisfy what I'm looking for but I'm just going to describe what I'd ...
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Does the relationship between plaintext and ciphertext moduli affect the security of BGV/BV SwHE?

The SwHE schemes due to Brakerski and Vaikuntanathan (BV) and Brakerski-Gentry-Vaikuntanathan (BGV) have common concept in which the message bit is put in the least significant bit of the ciphertext. ...
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Is there a way to perform a one way function on encrypted data?

Does the following scheme exist? Let f be a one-way function (say, an encryption scheme). Let $Enc_{sk}(x)$ be an encryption of x. We then have $Eval_{pk}(f, Enc_{sk}(x)) = f(x)$. Note that this is ...
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Multi-party computation with only 1 party?

MPC is $f(E_1(a), E_2(b)) = c$, where $E$ is encryption by different keys $k_1$ and $k_2$. Homomorphic encryption is $f(E_1(a)) = E_1(c)$, where the input and output are encrypted. I want $f(E_1(a)) ...
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Paillier's Cryptosystem - Homomorphism

I'm lacking quite some mathematical knowledge here, but could anyone please explain to me why the Paillier cryptosystem is still (additive/multiplicative) homomorphic despite introducing a random ...
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Complexity of computing zk-SNARK Proofs

Disclaimer: I have no background in cryptography, and everything I'm asking about is what I've learnt from last couple of days of frantic reading on this topic. Any help is much appreciated. Q: What ...
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Range query on array of encrypted data using homomorphic encryption

Given an array or database entries of encrypted data is it possible given a min/mix value to get a range of encrypted entries? The min and max values would also be encrypted.
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What is the current state-of-the-art of function-private functional encryption?

Are there any known constructions of functional encryption with function-privacy for arbitrary functions (e.g. not just inner-product)? If so, are these constructions currently feasible or for now ...
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How the FHE encrypts a k-bit message just with one-bit encryption scheme?

I'm reading "Fully Homomorphic Encryption over the Integers"——the first generation of FHE. However, this paper seems to detail a scheme to encrypt each bit in a message. I'm very confused about how to ...
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Homomorphic Modular Reduction for Secure Storage

My question is quite similar to Homomorphic modulo, but I want to give a context where the operation is carried in an outsourced environment. Are there any specific homomorphic cryptographic schemes ...
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Question about Gentry's “Computing Arbitrary Functions of Encrypted Data”

I am working through the "Computing Arbitrary Functions of Encrypted Data" by Gentry, trying to understand more about Fully Homomorphic Encryption. I'm stuck trying to understand why his "Somewhat ...
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difference between function f in eval and dec of homomorphic authenticated encryption

In the homomorphic authenticated encryption, as described 1, there are Eval and Dec PPT algorithms: In Eval, f is the function to be performed on the encrypted data. However, I need to know why it ...
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Do any NIST PQC have “homomorphic” public keys, in the sense that any two pubkeys derive a combination pubkey?

Background: The MathMesh crypto platform (refs at the bottom) is a newly-proposed technology stack which has been somewhat cheekily called a "Grand Unified Theory of Security on the Internet". Its "...
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Does homomorphic encryption hide the algorithm itself?

The question is rather simple, but finding resources and answers quite tricky. Homomorphic encryption should enable us to compute over encrypted data. What if the algorithm for computing should be ...
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Meaning of “integers modulo 4 ” in “Fully homomorphic encryption modulo Fermat numbers” scheme

My question refers to the paper "Fully homomorphic encryption modulo Fermat numbers" by Antoine Joux. On page 3, the author describes a basic concept of the system: As many FHE systems, we deal ...
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Is there any implementation of threshold BGN homomorphic encryption?

The BGN paper (Evaluating 2-DNF Formulas on Ciphertexts) used a threshold variant of BGN. I also want to use this cryptosystem, however, I cannot find any open-source implementation. Is there any such ...
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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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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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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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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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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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