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52 votes
Accepted

How is the Swiss post e-voting system supposed to work, and how was it wrong?

In the Swiss Post electronic voting protocol, after voters submit ballots, they are scrambled individually and shuffled together so that they cannot be traced back to voters to find who voted for whom—...
Squeamish Ossifrage's user avatar
17 votes

How is the Swiss post e-voting system supposed to work, and how was it wrong?

The problem was the poor design of the scheme, specifically the part for universal verifiability. As the paper Ceci n’est pas une preuve states: To guarantee anonymity of the votes the scheme makes ...
AleksanderCH's user avatar
  • 6,462
10 votes

Any ideas to make an Electronic Voter Machine more secure?

We can't make satisfactory Electronic Voting Machines. Their design face conflicting goals that are impossible to reconcile, even in the simplest conceivable use case: a yes/no vote, a single machine. ...
fgrieu's user avatar
  • 142k
7 votes
Accepted

Have I made any glaring mistakes in my use of Yao's garbled circuits?

Unfortunately, the answer to your question is yes. You have made glaring mistakes. In particular, Yao's garbled circuits are suited for two-party computation only, and here you wish to carry out a ...
Yehuda Lindell's user avatar
5 votes
Accepted

How do voters verify a Helios (v3) election result?

How does an average voter know that his vote actually counted? He doesn't have any way of performing the summation and obtaining the private key to decrypt. This is not actually true. He does have a ...
mikeazo's user avatar
  • 38.7k
5 votes

How to create a decentralized secret ballot among a small group of people?

Electronic voting schemes constitute a big area of cryptographic research. The problem is complicated and multifaceted, and there are still no end-to-end secure schemes that provide desirable ...
Mark's user avatar
  • 655
5 votes
Accepted

Cryptographically secure shaming

There is a very recent paper that solves this problem at a large scale using secure computation techniques: How to (not) share a password: Privacy preserving protocols for finding heavy hitters ...
Mikero's user avatar
  • 13.4k
4 votes

What is chain voting?

After a small search; it is a vote buying scheme. Chain voting, a vote buying scheme in which a crook gives the voter a pre-voted ballot, the voter votes that ballot, and then after leaving the ...
kelalaka's user avatar
  • 48.8k
4 votes
Accepted

Why is this voting system not secure?

Unfortunately, most of the reasons that e-voting is not popular have nothing to do with the integrity of the underlying mathematics. This makes the question slight moot on a cryptography forum, but ...
Paul Uszak's user avatar
  • 15.5k
4 votes

Providing tokens for anonymous survey

Blind signatures One easy way to let users swap tokens is to let them request the authority re-issue tokens blindly. This is how e-cash works but here instead of issued notes being redeemable for ...
Richard Thiessen's user avatar
3 votes
Accepted

Non interactive ZKP that encrypted additive elgamal message is in set of valid messages

The standard solution is to use a proof of encryption of zero, coupled with an or proof and a careful choice of ciphertexts. A proof of encryption of zero is a proof that the decryption of a ...
K.G.'s user avatar
  • 4,742
3 votes

E-voting: public tallying vs. vote selling

The second property is formally called receipt freeness. Any voting system based on probabilistic encryption cannot be receipt free, because the voter uses a random value to construct the vote, this ...
Panagiotis Grontas's user avatar
3 votes

Easy to implement proof of shuffle

Andrew Neff's verifiable shuffle scheme A Verifiable Secret Shuffle and its Application to E-Voting is implemented by the DeDiS Advanced Crypto Library for Go A working example program that uses the ...
Sean's user avatar
  • 51
3 votes

Providing tokens for anonymous survey

Since this is a survey, I assume that the submissions do not need to be publicly verifiable. A simple approach you can use is Verifiable Oblivious Pseudorandom Functions (VOPRF). This is the technique ...
knaccc's user avatar
  • 4,732
2 votes
Accepted

Why doesn't this operation reveal the voter's message?

I figured it out, it's quite simple actually. The $d$ values (and $r$ values) are all exponents and chosen from $\mathbb{Z}_q$. Thus all calculations on them directly take place in $\mathbb{Z}_q$. ...
Rhyzomatic's user avatar
2 votes
Accepted

Anonymity problem after voting with blind signatures

The problem is, that you are actually checking a tautology and this is no danger to deanonymization. Let me explain it to you with a simple example of 2 signatures: Lets say we want to blindly sign ...
DrLecter's user avatar
  • 12.6k
2 votes
Accepted

How might one create a system of election by lot (sortition) that is both secure and verifiable?

I'm going to try to answer a more modest version of your question. Imagine that the Dishonest Society, a small club of 100 members, needs to take care of an Arduous Task that will require 5 people to ...
kiwidrew's user avatar
  • 488
1 vote

Any ideas to make an Electronic Voter Machine more secure?

I will give some links; E-voting experiments end in Norway amid security fears If it ain’t broke, don’t fix it: Australia should stay away from electronic voting DEFCON 25 Voting Machine Hacking ...
kelalaka's user avatar
  • 48.8k
1 vote
Accepted

Paillier versus Lifted ElGamal for homomorphic addition for e-voting

So in general ElGamal encryption is only homomorphic wrt. multiplication. However with a few tweeks one can transform ElGamal to exponential ElGamal (and I guess that is what you are referring to). ...
Reppiz's user avatar
  • 191
1 vote

What is blindness and forgeability in Chaum's blind signature scheme?

Highly suggested paper: Security of Blind Signatures Revisited by Dominique Schröder et al. Especially have a look at Section 3, where the Unforeability and Blindness security games are defined. In ...
István András Seres's user avatar
1 vote

What is blindness and forgeability in Chaum's blind signature scheme?

It (Blind Signature) is unconditionally blind, because if you take a blind message $m\cdot r^e$ and then sign it, you get $m^d \cdot r$ which distributes like a random element in a subgroup of $Z^{*}_{...
yacovm's user avatar
  • 209
1 vote

Murder Mystery Party

With some assumptions I think you can do this with a simple protocol. We will break i into two parts: attempt an allocation which may succeed with reasonable liklyhood. And verify it. If ...
Meir Maor's user avatar
  • 11.8k
1 vote
Accepted

Maintaining validity of ZKP throughout re-randomization of homomorphic ciphertext without linkability to previous ciphertext

First (if it's not the case) you have to read carefully the original Groth-Sahai paper. We can focus on a concrete example to understand why it's possible: in the "SXDH" setting for example (...
Ievgeni's user avatar
  • 2,605
1 vote
Accepted

How to prove element equality in G1 using Groth-Sahai proofs

First of all, the idea of proving element equality does not make much sense, since that would reveal the secret element. $prove(X == T)$ with secret $X \in G_1$ and public constant $T \in G_1$ reveals ...
Simon Warta's user avatar
1 vote

Non-interactive public sum of private values

If all the participants have a random secret key which sums to 0. They can each post the sum of their key with their number. Anyone can then some the values posted, the key will cancel out and we what ...
Meir Maor's user avatar
  • 11.8k
1 vote
Accepted

Anonymity of Paillier cryptosystem in e-voting system

You've discovered some of the challenges of secure electronic voting. As you can see, merely having a cipher that allows you to confidentially tally numbers is not sufficient to conduct a secure ...
Ella Rose's user avatar
  • 19.6k
1 vote

Revealing vote after time

Based on @Cort Ammon suggestion and some additional consultation i think the below will work Each of the 5 parties could publish Hash(vote || random bytes), because of the random bytes it would ...
Kam's user avatar
  • 11
1 vote

Zero-knowledge voting with hidden weights

One approach might be the usage of a homomorphic cryptosystem like the Paillier cryptosystem, while the specific protocol properties depend on your use case. For more detailed description of Paillier ...
Jerre's user avatar
  • 116
1 vote

Privacy of vote from tallying authority in El Gamal Voting Schemes

For Shamir sharing scheme, an individual authority can only decrypt his share of anything is has, including individual voter ballot. With this scheme, such a share would give no information about the ...
Vadym Fedyukovych's user avatar

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