# Tagged Questions

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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### Applying machine learning algorithms to homomorphic encrypted data

I have a basic understanding of encryption and I got back to the topic because of an interesting site that encrypts financial data using homomorphic encryption (HE) and I would be happy for any input ...
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### Homomorphic Encryption operation for regression

I must be missing something, and I am sorry if this is a novice question... I have seen in places (eg. https://crypto.stanford.edu/~dwu4/talks/SecurityLunch0214.pdf page 13) that linear regression is ...
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### SEAL Homomorphic multiplication

In SEAL homomorphic encryption library, there is an internal procedure to decompose a polynomial with large coefficients into a vector of polynomials with smaller coefficients. The procedure is ...
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### Why does Paillier have poor performance?

Can anyone explain to me why Paillier crypto system does not provide good performance? I read here (pdf) that RSA and ElGamal provide better performance than Paillier algorithm.
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### Difference between a circuit and a normal function

I've seen the word circuit used in many crypto contexts (for example, regarding FHE in this pdf). I've always thought of a circuit as another word for a program or function. But is there a difference -...
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### How do they avoid Zero Knowledge Proofs in the paper Priced Oblivious Transfer: How to sell Digital Goods?

I don't understand a part of the paper Priced Oblivious Transfer - How to Sell Digital Goods. Particularly, the authors avoid using zero knowledge proofs and in section 3.3 they explain how they do ...
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### Can homomorphic encryption support the operation of exponentiation where both base and exponent are encrypted?

Does it exist some homomorphic encryption libraries or packages which can support the exponentiation where both base and exponent are encrypted? For example, $y = a^b$, where both $a$ and $b$ are ...
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### Malleable encryption

What I would like to achieve is the following: Alice sends to Bob the encryption of a datagram that has the following format: ...
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### Are Paillier and El Gamal encryption schemes secure against quantum attacks?

I was wondering if there is a security difference between Lattice based homomorphic encryption schemes versus an partially homomorphic encryption scheme like Paillier, and El Gamal encryption schemes ...
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### Finding $f^{-1}$ in the YASHE keygen algorithm

In the YASHE (Yet Another Somewhat Homomorphic Encryption) algorithm, the beggining of the key generation step specifies: Sample $\ f',g ← χ_{key}$ and let $\ f = [tf' + 1]_q$. If $\ f$ is ...
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### identifying presence of encryption of zero in additive homomorphic encryption

Lets say the server has corpus of ciphertext contains $enc(a),enc(b),enc(c), \dotsc enc(x)$. The encryption function is an additive homomorphic scheme (like Paillier). The server knows only the public ...
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### Equality checking using additive homomorphic encryption

Given two ciphertexts $c_1 = enc(p_1)$ and $c_2= enc(p_2)$ using any additive homomorphic encryption scheme (or specifically Paillier). Can we find out whether the underlying plaintexts $p_1,p_2$ ...
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### How to generate 1000 prime number of 1024-bit with much less time?

I am generating thousand prime number of 1024 bit each. But it takes lots of time. My procedure is as follows. Generate prime number using ...
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### Additive homomorphic encryption over small fields

Are there encryption schemes that are additively homomorphic with respect to small fields such as $\mathbb{F}_{2^4}$ or $\mathbb{F}_{2^8}$?
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### Practical multivariate quadratic FHE – how does it compare to other FHEs?

Came across this startup claiming practical FHE and then their blog post going into some additional details on it. It was my understanding that practical FHE is still years/decades off. They said ...
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### Comparison on Ciphertext with Helib

Is it possible to do a greater than homomorphic comparison in the form ($c_1 < c_2$) on two ciphertexts using Helib? The equal comparison ($c_1 == c_2$) can be done in modulus 2 by adding both ...
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### Homomorphic multiplication by a scalar

Few homomorphic encryption schemes like Paillier , Ring-LWE support homomorphic multiplication operation by a scalar apart from additive homomorphic property. Loosely they could be defined as below ...
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### Can we do modulus switching for number theoretic encryption?

Can we do modulus switching for number theoretic encryption such as Paillier or ElGamal?
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### About BGV Scheme Batching Technique

I am reading BGV12 about BGV homomorphic scheme right now.But I am being stuck to understand Batching technique in this paper. In Pack function (page 32),this paper feeds ciphertext $c_i$ and sk $s_1$...
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### Analysis of DGHV Security

I want to know how security of DGHV can be breached using oracle and Binary GCD. As I study this paper : Fully Homomorphic Encryption over the Integers But I am not able to understand Section 4.1: ...
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### Quantifying bit security for smart-vercauteren encryption scheme

I am working on project that requires to compare in terms of security between two encryption schemes, one of them is the SV scheme. However, I dont know what are the steps exactly towards quantifying ...
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### How to Perform Computation on AES Encrypted Data

I have this code that successfully performs symmetric encryption using AES algorithm. How can I go about performing computation on it to achieve somewhat homomorphic encryption? ...
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### How to prove hardness of approximate-GCD problem?

I am trying to prove the security of my system using the hardness assumption of the approximate-GCD problem using contradiction, i.e. If the attacker is able to break in our scheme, then attacker ...
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### How do voters verify a Helios (v3) election result?

So from my understanding of verification specification version 3, a Helios election proceeds as follows: A voter retrieves the system's public key to encrypt their vote & submit it. The voter ...
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### Homomorphic Encryption or not

I am a beginner to homomorphic encryption scheme. As far as I think, it is just a kind of concealing real value without using standard encryption algorithms such as AES,DES or RSA. For example , for ...
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### Beavers Triple Vs BGW Multiplication on MPC

Typically MPC protocols that are secure against semi-honest adversaries recommend the use of the revised GMW multiplication protocol by Gennaro et al. This is not the case against Active adversaries ...
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### Confusion about definition of homomorphic encryption

I am trying to better understand homomorphic encryption, but I feel like I keep getting inconsistent information in the papers that I am reading. One of the papers I am reading says the following: ...
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### How does order-preserving encryption work on string?

I have read “How does order-preserving encryption work?”. After that, I completed order-preserving encryption on integer data. Now, I have four questions in this subject: Is it possible to apply ...
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### What would be a typical value for the security parameter of the Fully Homomorphic Encryption over the Integers scheme?

The parameters of the Fully Homomorphic Encryption scheme by Dijk et.al are chosen according to the value of the security parameter ${\lambda}$, section 3 of the aforementioned article. What is the ...
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### Scalability of homomorphic tallying

Whenever I look at online voting schemes, the idea of homomorphic encryption being a key concept, specially in the form of homomorphic tallying, appears to be universally accepted. The accepted answer ...
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### How to make the range of modulo $p$ to $[-\frac{p}{2};\frac{p}{2}]$?

I am using NTL (A Library for doing Number Theory) to implement a FHE (Fully Homomorphic Encryption) scheme. In general, the range of modulo p is $[-\frac{p}{2};\frac{p}{2}]$ in FHE scheme. However, ...
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### Why doesn't this operation reveal the voter's message?

I am working my way through this paper. I am trying to figure out the OR zero knowledge proof in figure 2. The prover is verifying that she has correctly voted, and that her input satisfies \log_gx=\...
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### homomorpic encryption [closed]

I am doing project k-nearest neighbor classification over semantically secure encrypted relational data I have doubt for in smin algorithm in 1)Li ← Wi ∗ Φir′; ri′ ∈R ZN this line it the out put is ...