Hääl - Anonymous Electronic Voting System on Public Blockchains

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dateFirst release -
dateLatest release -
updateLast update 2020-12-21


Anonymous Electronic Voting System on Public Blockchains

Hääl means voice in Estonian. Voice means power of people.

This code is a proof-of-concept of the protocol presented on the whitepaper located at the root folder. It describes a full process for an e-voting system, using public blockchains and without a mixnet or an oracle for tallying the votes.

The full protocol makes use of:

  • Zero-knowledge proofs (with zk-snarks verified on-chain)
  • Homomorphic encryption (Paillier protocol + zk)
  • Stealth addresses (as proposed by Peter Todd, but ported to ethereum)
  • Encrypted notes (e.g Zcash, AZTEC)
  • Cryptography challenges (based on Sigma protocol)
  • Digital signatures
  • Ethereum (or another blockchain capable of running dApps)
  • other technologies described on the whitepaper

Working in progress. No access control layers implemented in this PoC to avoid overhead, implement it as your needs. All contributions are welcome.



  • ganache-cli ^6.3.0 or Ganache ^1.2.2
  • Node 8
  • Solidity ^0.4.5
  • Yarn ^1.13.0


# yarn install && yarn truffle build && yarn ganache-cli


(on a new terminal)
# yarn truffle test

Manual installation (for debugging purposes)

Install and set the correct version of NodeJS.

$ apt-get install node npm
$ curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.32.1/install.sh | bash 
$ nvm install 8
$ nvm use 8

Download third-party dependencies.

$ curl -o /usr/bin/solc -fL https://github.com/ethereum/solidity/releases/download/v0.4.25/solc-static-linux
$ chmod u+x /usr/bin/solc

Get https://github.com/trufflesuite/ganache/releases/download/v1.2.2/ganache-1.2.2-x86_64.AppImage
$ chmod +x ganache-1.2.2-x86_64.AppImage


$ npm install -Wno-cast-function-type 2> debug.log
$ node ./node_modules/truffle/build/cli.bundled.js build
$ ./ganache-1.2.2-x86_64.AppImage (on a new terminal)
$ node ./node_modules/truffle/build/cli.bundled.js test

Compiler warnings

Is expected to receive the warning below during contracts compilation:

haal/contracts/HAAL/haal.sol:2:1: Warning: Experimental features are turned on. Do not use experimental features on live deployments.
pragma experimental ABIEncoderV2;

That message appears because we're using an experimental method to fill arrays (bytes[]):

function addVote(
        bytes[] _president, 
        bytes[] _senator, 
        bytes[] _stateGovernor,

function getVotes(uint _index) view public returns(bytes[], bytes[], bytes[])

Apache License https://www.apache.org/licenses/LICENSE-2.0