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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Security analysis of encrypting a matrix after homomorphic encryption by the random mask

Problem Definition Alice has two private matrices $M_A$ ($N*M$), $M_a$, where $M_a$ is the binary matrix of $M_A$ Bob has a private matrix $M_B$($N*M$) Alice and Bob are semi-honest server and ...
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Is there anyone intrested in quantum fully homomorphic encryption?

Recently, I have read a paper named "Classical Homomorphic Encryption for Quantum Circuits". The author claims a quantum scheme that can apply an encrypted (like GSW encryption) bit to ...
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AES homomorphic updates

I am looking for some help regarding something I am trying to do and I think to solution might be in Homomorphic encryption. Person A and B encrypt the same number(unsinged long) N using AES with ...
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How many known plaintexts are required to break a system with this property?

Suppose we have an $n$ bit block cipher $E$ with a key $k$ that has the following property $$E(k; m_1⊕m_2) = E(k;m_1) ⊕E(k; m_2).$$ How many minimum number of chosen plaintexts are required to ...
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Is there a way to confirm that a homomorphic division (multiplication with inverse) using ElGamal produced the correct result?

By running some tests I observed that if I perform a homomorphic division (multiplication with the multiplicative inverse) between two values using the ElGamal scheme, I get the correct result when ...
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Bitwise operations in FHE

Im reading about FHE and the libraries implementing it (SEAL, HELib). I saw that SEAL doesn't support bitwise operations but I wondered if its theoretically feasible. For example, bitwise-ing XOR an ...
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Proving LWE inversion in Micciancio-Peikert-2012 lattice trapdoors

I'm looking through the lattice trapdoor construction in https://eprint.iacr.org/2011/501. To summarize, assume we have a matrix $G$ where, on input $b$, we can efficiently find $(s,e)$ such that $s^...
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How to add ciphered numbers under benaloh's scheme?

In the answer for Is it possible to subtract/multiply numbers using homomorphic encryption? it says: To add two encrypted numbers, one could use Benaloh, Damgård–Jurik, or several other known ...
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Privacy preserving aggregation of encrypted data

I have the following problem: I have $t$ servers $S_1, S_2, S_3, \ldots, S_t$, each of them storing some $key : value$ list. They have to upload this data into a big dropbox server $D$, but in such a ...
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How can I use two different public keys with the same private key for fully homomorphic encryption?

I am pretty new to cryptography. Recently I run into this question where I have two different public keys with the same private key, and I need them for fully homomorphic encryption. Let's say ...
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What is the key generation and management process of a fully homomorphic encryption system?

I've been very interested in fully homomorphic encryption lately, and I understand the concept well enough, but there is one thing that I don't understand... What is the key creation and, more ...
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How is a non-interactive zero-knowlege proof constructed using homomorphic encryption?

I've been reading too much, and I still haven't found the explaination I so crave. I'm looking specifically at zk-SNARKs, as implemented by ZCash. They say they use homomorphic encryption in their non-...
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How is it that homomorphic encryption can encrypt program code and run it without decryption?

In my journey of interest in the world of homomorphic encryption has led me to a concept floating around the internet where they describe homomorphic encryption being used with "mobile agents&...
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The existing approaches based on machine learning for cryptography [closed]

i'm working on a paper about Machine learning and Deep Learning and i'm wondring about the uses of this domain in cryptography!! so what are these application of Ml that we use in cryptography and the ...
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Convert homomorphically encrypted decimal number to homomorphically encrypted binary number

I am trying to convert a homomorphically encrypted integer to a homomorphically encrypted binary number (in vector form like {Ciphertext(1),Ciphertext(1),Ciphertext(0),Ciphertext(1)}), which I cannot ...
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Is it possible to trim some encrypted values under fully homomorphic encryption

Suppose we have $N$ encrypted values under homomorphic encryption (BFV/BGV ..), and we know that $M$ of them are below $t$. Is it possible to remove those $M$ values? It is known that some methods (e....
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Can I use RSA as hash function?

My end goal is to have an encryption function $e$ and a hash function $H$ such that for all m we have: $$H(e(m)) = e(H(m))$$ This would work if we use RSA encryption along with RSA "hash", ...
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Homomorphic encryption scheme for modulo reduction

I want to know if there is any Homomorphic encryption scheme that supports modulo reduction, i.e., using $Enc_{pk}(m)$ and a public $w$ to compute $Enc_{pk}(m \mod w)$. Thank you.
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DES decryption of the homomorphic encryption ciphertext

I implemented an application using partial homomorphic encryption for outsourced computations. To get an efficient bandwidth, I am thinking to apply (DES) symmetric algorithm to encrypt the message ...
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Multiplication under different keys in BGV

I have a question about BGV homomorphic encryption. If we have ciphertexts c1 and c2 under the same key s, the tensor product c3 of c1 and c2 can be decrypted by the tensor product of s and s. If c1 ...
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Is there a way to change encryption scheme from AES to FHE without data leakage?

So let's say that we have encrypted some data using symmetric encryption in this case AES. And we want to change it to homomorphic encryption but without decrypting the data and encrypting it again ...
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Which are the current solutions to the illegal values in the homomorphic secret sharing?

There is a usual example about homomorphic secret sharing, focused on e-voting. Supposing we use Shamir's scheme for the Secret Sharing system, a participant generates a polynomial whose a0 is +1 (yes)...
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How to generate Multiple Encryption Keys for use in RSA polymorphic multiplication

I am a long time scroller, first time poster in the crypto stack. I've recently been finding myself leaving the realm of mainstream/standard crypto (imo that consists of symmetric/asymmetric ...
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Proof of lemma 1 Paillier encryption

In the original paper of Paillier, lemma 1 shows why $n$ must divide the order of $g$. What I don't understand in the proof of this lemma is why $g^{x_2-x_1}(y_2/y_1)^n$ implies $g^{\lambda(x_2-x_1)}$....
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Hash chain based secret revealing using homorphic princples?

I have recently been looking into Homomorphic encryption and I am looking for a specific hash-based encryption/decryption scheme. I don't need a full implementation but I am not sure if what I want ...
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Timing attacks on homomorphic encryption

I've been wondering for a long time about programs that could potentially break fully homomorphic encryption schemes: ...
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Implementing BFV Relinearization

I'm currently working on a Python implementation of the BFV[12] cryptosystem. I got to a point where key generation, encryption, addition and decryption works as expected. Where I'm struggling with ...
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Paillier scheme and noise growth

Does the problem of noise growth exist in the Paillier homomorphic scheme ?
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CKKS Encoding scheme explanation

I have been going over the CKKS Homomorphic Encryption scheme but I can't seem to understand how the mapping takes place while encoding. I don't get what the line below is trying to convey. I saw this ...
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Zk-Snarks vs Homomorphic Encryption

I have been reading a bit about encryption algorithms. I have come across these two algorithms.My use case is the ability to work with encrypted data and my data will be string data. I see that ...
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Compute euclidian distance on encrypted data

The scenario is described as following: Let $A$ an user that is transmitting an encrypted (with its own public key $PK_A$) data vector containing its position as $p = Enc(PK_A, [x,y])$ towards a group ...
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Is there any cryptosystem that works on floating point real number?

I see that all cryptosystems are work on finite field. But i consider that have any cryptosystem that works on real number (do not consider the round step and it also can be an estimate cipher)
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Do any probabilistic hashing algorithms have additive homomorphism?

What I am looking for is a function that meets the following criteria: For each possible input (assume integers from [0, 255]), there must be trillions of possible outputs so as to prevent preimage ...
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In a FHE scheme, does the application of a mask to an encrypted vector increase its multiplicative level?

Forgive me if my nomenclature is off, I've only just started down the rabbit hole of FHE schemes. Basically, I was reading a paper proposed the use of an FHE scheme to preserve privacy of some data ...
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Homomorphic Multiplication Operation in BFV Scheme

I am working on BFV scheme and trying to create a very simple Python implementation. I am following the paper by Fan and Vercauteren. Most of the operations are easy to implement but I am having ...
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Is there such a concept as „encrypted operations“ on cyphertext? [duplicate]

Homomorphic encryption allows computation of (arithmetic or boolean) operations on ciphertext with the result being another ciphertext. In that case... client A ...
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Retrofitting software: the biggest problem with Homomorphic Encryption?

In my experience, conversations around Homomorphic Encryption tend to focus on the narrative "HE is the holy grail of secure computations, but it's still too computational intensive to be practical". ...
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Homomorphic encrypted streams (Paillier)

Situation: Alice (violin) and Bob (drums) play music together and want to (real-time) stream the concert to Carol. In order for Carol to save bandwidth, the stream is sent through a server which ...
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random mask reversible after homomorphic encryption

I would like to know if this process is feasible under homomorphic encryption, ideally under paillier or any other additive scheme Apply a mask X to obfuscate a message A ie. Am = A (op) X where (op)...
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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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