# Manual Integration

The following section is an excerpt of the article published on the Vocdoni Blog (opens new window), called Introducing Voting as a Service (opens new window).

This article was written before the VaaS API was available, and it details a low-level way to use the Vocdoni VaaS directly with the dvote-js package. Integrators can now use the high-level API instead.


The contents of this article are outdated. An up to date version will be available soon.
Use the article as an introduction and combine it with this end-to-end example (opens new window).

Conducting secure voting processes is far from simple, and today we are only focusing on the first steps. Vocdoni is conceived as a set of decentralized components which can operate as a whole.

  • The Ethereum blockchain to declare organizations and their voting processes (Layer 1).
  • Decentralized metadata retrieved via IPFS.
  • The purpose-specific voting blockchain, where votes are validated and registered (Layer 2)
  • The public gateways, providing easy access to the decentralized components above.
  • The census registry (the user database to generate the census).

Every single one of these components can be replaced by your own instances without any kind of vendor lock-in.

If your organization already has an existing user database, Vocdoni's Governance as a Service is the best fit.

# How it works

# Before the process

In Vocdoni, identities arise from cryptographic key pairs (ECDSA). When people are added to a database, their public key (opens new window) is registered.

To create a voting process, the first step is to generate a snapshot of the census. The census consists of a Merkle Tree (opens new window) with the public keys (opens new window) of everyone who is eligible to vote. No personal data is involved.

The census snapshot is then uploaded and pinned to a decentralized storage like IPFS (opens new window), which ensures that everyone will be able to check it out.

Then the voting process details are declared on the Ethereum (opens new window) smart contract (opens new window), so that anyone with internet access can fetch them, get the metadata, get the location of the census, etc.

# During the process

Using their private key and a decentralized Gateway (opens new window), eligible voters can fetch a Merkle proof to prove that their key pair belongs to the census Merkle Tree (opens new window). They sign their vote envelope with the key above and submit it using whatever Gateway (opens new window) they like. Even their own.

Votes are relayed to the custom voting blockchain, validated and included in the next block.

As the process goes on, anyone with network access can listen for vote transactions, verify them by themselves or even use the block explorer (opens new window) to do it manually.

# After the process

When the vote is over, the oracle will trigger a process end transaction. At this point, the process will stop accepting valid votes and Gateways will be able to compute the scrutiny of the process. Even your own gateways can.

Optionally, an oracle can read the final results and publish them on the smart contract where the process was created, so that results are notarized on the Ethereum blockchain.

Since the process operates on an L2 sidechain, users don't even need to know about metamask (opens new window), exchanges or gas fees (opens new window). All they do is open an app or a web site and use their keys (under the hood) to sign and submit a vote envelope. The governance infrastructure does the rest.

# Get started

Enough talk, let's see how you can create an entity and publish your first voting process.

# Entity creation

Make sure you have Node.js (opens new window) 12 installed on your computer.

In an empty folder, create a package.json file by running

$ npm init -y
Wrote to /home/user/dev/governance-as-a-service/package.json:

  "name": "governance-as-a-service",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  "keywords": [],
  "author": "",
  "license": "ISC"

Next, install the DVoteJS dependency and two dev dependencies to support TypeScript:

$ npm i dvote-js
$ npm i -D typescript ts-node

Edit the scripts section of package.json and leave it like this:

  "scripts": {
    "main": "ts-node index.ts"

Then, let's create a file named index.ts and create a function to generate the wallet of our new entity:

import { Wallet } from "ethers"

function makeEntityWallet() {
    console.log("Creating entity wallet")
    const entityWallet = Wallet.createRandom()

    console.log("Entity address:", entityWallet.address)
    console.log("Entity private key:", entityWallet.privateKey)


To check that it works, let's run npm run main:

$ npm run main
Creating entity wallet
Entity address: 0x1048d8cB20fE806389802ba48E2647dc85aB779a
Entity private key: 0x6d88d78a4a76e42144b6867fdff89477f0a3b805d85b97cd46387a2f770f91f1

So here's our wallet, what's next?

In this example, we will be using an Ethereum testnet called Sokol. Write down your private key and and use the address to request some test coins from the faucet (opens new window). You will need them to send some transactions.

Sokol Faucet

Now, instead of creating a random wallet, we should use the one that received the test ether. In the lines above, replace this:

const entityWallet = Wallet.createRandom()

Into this:

// Use your private key here
const entityWallet = new Wallet("0x6d88d78a4a76e42144b6867fdff89477f0a3b805d85b97cd46387a2f770f91f1")

Obviously, make sure to store any real private key nowhere within the source code or Git in general.

Now we need to get a pool of gateways and connect to one of them:

import { GatewayPool } from "dvote-js/dist/net/gateway-pool"

let pool: GatewayPool

async function connect() {
    // Get a pool of gateways to connect to the network
    pool = await GatewayPool.discover({ networkId: NETWORK_ID, bootnodesContentUri: GATEWAY_BOOTNODE_URI })
    await pool.connect()

const disconnect = () => pool.disconnect()

Then, let's define the metadata of our Entity and make it available on IPFS and Ethereum. Add the following code to index.ts:

import { EntityMetadata } from "dvote-js"
import { updateEntity } from "dvote-js/dist/api/entity"

async function registerEntity() {
    // Make a copy of the metadata template and customize it
    const entityMetadata: EntityMetadata = Object.assign({}, Models.Entity.EntityMetadataTemplate)

    entityMetadata.name.default = "Vilafourier"
    entityMetadata.description.default = "Official communication and participation channel of the city council"
    entityMetadata.media = {
        avatar: 'https://my-organization.org/logo.png',
        header: 'https://my-organization.org/header.jpeg'
    entityMetadata.actions = []

    const contentUri = await updateEntity(entityWallet.address, entityMetadata, entityWallet, pool)

    // Show stored values
    console.log("The entity has been defined")

And then:

$ npm run main
Setting the entity metadata
WARNING: Multiple definitions for addr
WARNING: Multiple definitions for setAddr
The entity has been defined


This is what we just did:

  • We created JSON metadata containing the custom details of our entity
  • We pinned the JSON content on IPFS using a gateway from the pool
  • The hash of our metadata is QmdK5TnHDXPt4xozkuboyKP94RTrUxFr1z9Pkv5qhfahFG and should be available from any IPFS peer (opens new window)
  • An Ethereum transaction was sent to the entities contract, defining the pointer to our new metadata.

The value on the smart contract can only be updated by our wallet, the blockchain ensures the integrity of our data and IPFS ensures its global availability.

# Visualizer

To check that our entity is properly declared, we can check it on the visualizer: https://app.dev.vocdoni.net/entities/#/<entity-id>

This is the link in our case (opens new window).

Keep in mind that we're using a testnet and some of the data might be eventually disposed.

# Census generation

Our entity is ready, now it can handle voting processes. But before we can create one, we need a census of the people who can vote.

As we said, digital identities arise from a cryptographic keypair. The ideal scenario is when the identity is generated on the user's device and only the public key is shared, but for the sake of simplicity, we will create a few identities ourselves.

let votersPublicKeys: string[] = []

function populateCensusPublicKeys() {
    for (let i = 0; i < 10; i++) {
        const wallet = Wallet.createRandom()
    console.log("Voter's public keys", votersPublicKeys)

Which results in

Voter's public keys [

Then we can upload the census claims to a gateway and publish it:

import { addCensus, addClaimBulk, getRoot, publishCensus } from "dvote-js/dist/api/census"

let merkleTreeOrigin: string
let merkleRoot: string

async function publishVoteCensus() {
    // Prepare the census parameters
    const censusName = "Vilafourier all members #" + Math.random().toString().substr(2, 6)
    const adminPublicKeys = [await entityWallet["signingKey"].publicKey]
    const publicKeyClaims = votersPublicKeys.map(k => digestHexClaim(k)) // hash the keys

    // As the census does not exist yet, we create it (optional when it exists)
    let { censusId } = await addCensus(censusName, adminPublicKeys, pool, entityWallet)
    console.log(`Census added: "${censusName}" with ID ${censusId}`)

    // Add claims to the new census
    let result = await addClaimBulk(censusId, publicKeyClaims, true, pool, entityWallet)
    console.log("Added", votersPublicKeys.length, "claims to", censusId)
    if (result.invalidClaims.length > 0) console.error("Invalid claims", result.invalidClaims)

    merkleRoot = await getRoot(censusId, pool)
    console.log("Census Merkle Root", merkleRoot)

    // Make it available publicly
    merkleTreeOrigin = await publishCensus(censusId, pool, entityWallet)
    console.log("Census published on", merkleTreeOrigin)

Which results in:

Census added: "Vilafourier all members #550262" with ID 0x1048d8cB20fE806389802ba48E2647dc85aB779a/0x8e0c00cda17a132e2ce6c89072cc2037b0800c280c1ddba318eb2620fae2ff16
Added 10 claims to 0x1048d8cB20fE806389802ba48E2647dc85aB779a/0x8e0c00cda17a132e2ce6c89072cc2037b0800c280c1ddba318eb2620fae2ff16
Census Merkle Root 0xbf8572159929b4e37c40e2ce18fd46156e750a4aac1f06dbda3237edccc81115
Census published on ipfs://QmcTuUJbN1tEWA3nqHFU8N8iuUN2ymJoqW4UcKBzHuYrPw

Cool! Our entity is ready, and our first census is now public.

# Process creation

Now we are ready to create our fist process. To do so, we will use the values we generated previously and define the topic, the questions, the vote options, etc.

import { getEntityId } from "dvote-js/dist/api/entity"
import { estimateBlockAtDateTime, createVotingProcess, getVoteMetadata } from "dvote-js/dist/api/vote"

async function createVotingProcess() {
    const myEntityAddress = await entityWallet.getAddress()
    const myEntityId = getEntityId(myEntityAddress)

    const startBlock = await estimateBlockAtDateTime(new Date(Date.now() + 1000 * 60 * 5), pool)
    const numberOfBlocks = 6 * 60 * 24 // 1 day (10s block time)

    const processMetadata: ProcessMetadata = {
        "version": "1.0",
        "type": "poll-vote",
        "startBlock": startBlock,
        "numberOfBlocks": numberOfBlocks,
        "census": {
            "merkleRoot": merkleRoot,
            "merkleTree": merkleTreeOrigin
        "details": {
            "entityId": myEntityId,
            "title": { "default": "Vilafourier public poll" },
            "description": {
                "default": "This is our test poll using a decentralized blockchain to register votes"
            "headerImage": "https://images.unsplash.com/photo-1600190184658-4c4b088ec92c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1350&q=80",
            "streamUrl": "",
            "questions": [
                    "type": "single-choice",
                    "question": { "default": "CEO" },
                    "description": { "default": "Chief Executive Officer" },
                    "voteOptions": [
                        { "title": { "default": "Yellow candidate" }, "value": 0 },
                        { "title": { "default": "Pink candidate" }, "value": 1 },
                        { "title": { "default": "Abstention" }, "value": 2 },
                        { "title": { "default": "White vote" }, "value": 3 }
                    "type": "single-choice",
                    "question": { "default": "CFO" },
                    "description": { "default": "Chief Financial Officer" },
                    "voteOptions": [
                        { "title": { "default": "Yellow candidate" }, "value": 0 },
                        { "title": { "default": "Pink candidate" }, "value": 1 },
                        { "title": { "default": "Abstention" }, "value": 2 },
                        { "title": { "default": "White vote" }, "value": 3 }
    const processId = await createVotingProcess(processMetadata, entityWallet, pool)
    console.log("Process created:", processId)

    // Reading the process metadata back
    const metadata = await getVoteMetadata(processId, pool)
    console.log("The metadata is", metadata)

Which looks like this:

Process created: 0x82f42dc48bfbfa0bb1018bcb0f3a31f77d12ced1fda9566990d64d07be9a48a6
The metadata is {
  version: '1.0',
  type: 'poll-vote',
  startBlock: 2203,
  numberOfBlocks: 8640,
  census: {
    merkleRoot: '0x2044a23e328d75276a7e9e6bc1774eb67707597beba1cfdfde5e7fa174197101',
    merkleTree: 'ipfs://QmTFGgoDnMWhMU3BXxm4zTxeFZLPnRV1jiQgBqukzJPmo9'
  details: {
    entityId: '0xdeea56f124dd3e73bcbc210fc382154a11f3bab227af55927139c887e15573e4',
    title: { default: 'Vilafourier public poll' },
    description: {
      default: 'This is our test poll using a decentralized blockchain to register votes'
    headerImage: 'https://images.unsplash.com/photo-1600190184658-4c4b088ec92c?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1350&q=80',
    streamUrl: '',
    questions: [ [Object], [Object] ]

So, we just...

  • Defined the metadata of our process
  • Defined the block at which we would like the process to start
  • Declare the metadata of the process

As it happened before, the JSON metadata is pinned on IPFS and pointed to from the process smart contract. In addition, some metadata fields are also stored on the smart contract so they can be accessed on-chain.

The contract flags define how the process will behave, whereas the metadata is used to store the human readable content.

In about 2-3 minutes, the Ethereum transaction will be relayed to the voting blockchain as well. When the block number reaches startBlock, the process will become open to those who are part of the census. The startBlock value should be at least 25 blocks ahead of the current value.

# Visualizer

To check the new process, there are two web sites we can use:

  • https://app.dev.vocdoni.net/processes/#/<entity-id>/<process-id>
  • https://explorer.dev.vocdoni.net/process/<process-id>

In our case:

  • https://app.dev.vocdoni.net/processes/#/0xdeea56f124dd3e73bcbc210fc382154a11f3bab227af55927139c887e15573e4/0x82f42dc48bfbfa0bb1018bcb0f3a31f77d12ced1fda9566990d64d07be9a48a6
  • https://explorer.dev.vocdoni.net/process/0x82f42dc48bfbfa0bb1018bcb0f3a31f77d12ced1fda9566990d64d07be9a48a6

Again, this is a testnet and some of this data may have been cleaned up at some point.

# Voting

The previous code typically runs on the backend of your organization -you will simply choose to generate a census based on your specific organization's parameters.

This next portion, however, is meant to be executed on the voter's device. The specific method used to create and manage user keys is an important decision which presents a trade off between usability and security.

  • Users create the keys on their end
    • This allows for a self sovereign identity and provides higher privacy
    • However, users have to register the public key on your backend and you need to validate it
  • The organization creates one-time keys
    • The keys are not in the user's control
    • They don't need to register
    • They can simply receive a link and use it to vote, and then the key expires

Whatever your case is, we will illustrate a web browser environment where the voter fetches the process metadata, signs his/her choices and submits them to a gateway.

import { Wallet } from "ethers"
import {
} from "dvote-js/dist/api/vote"
import { getCensusSize, digestHexClaim, generateProof } from "dvote-js/dist/api/census"
import { waitUntilVochainBlock } from "dvote-js/dist/util/waiters"

async function submitSingleVote() {
    // Get the user private key from the appropriate place
    const wallet = new Wallet("voter-privkey")  // TODO: Adapt to your case

    // Fetch the metadata
    const processMeta = await getVoteMetadata(processId, pool)

    console.log("- Starting:", await estimateDateAtBlock(processMeta.startBlock, pool))
    console.log("- Ending:", await estimateDateAtBlock(processMeta.startBlock + processMeta.numberOfBlocks, pool))
    console.log("- Census size:", await getCensusSize(processMeta.census.merkleRoot, pool))
    console.log("- Current block:", await getBlockHeight(pool))
    console.log("- Current votes:", await getEnvelopeHeight(processId, pool))

    await waitUntilVochainBlock(processMeta.startBlock, pool, { verbose: true })

    console.log("Submitting vote envelopes")

    // Hash the voter's public key
    const publicKeyHash = digestHexClaim(wallet["signingKey"].publicKey)

    // Generate the census proof
    const merkleProof = await generateProof(processMeta.census.merkleRoot, publicKeyHash, true, pool)

    // Sign the vote envelope with our choices
    const choices = [1, 2]
    const voteEnvelope = await packagePollEnvelope({ votes: choices, merkleProof, processId, walletOrSigner: wallet })

    // If the process had encrypted votes:
    // const voteEnvelope = await packagePollEnvelope({ votes, merkleProof, processId, walletOrSigner: wallet, encryptionPubKeys: ["..."] })

    await submitEnvelope(voteEnvelope, pool)
    console.log("Envelope submitted")

That's quite a lot so far!

To check for the status of a vote, you can append these extra calls at the end:

import { getPollNullifier, getEnvelopeStatus } from "dvote-js/dist/api/vote"

    // ...

    // wait 10+ seconds
    await new Promise(resolve => setTimeout(resolve, 1000 * 10))

    // Compute our deterministic nullifier to check the status of our vote
    const nullifier = await getPollNullifier(wallet.address, processId)
    const status = await getEnvelopeStatus(processId, nullifier, pool)

    console.log("- Registered: ", status.registered)
    console.log("- Block: ", status.block)
    console.log("- Date: ", status.date)

The output:

- Starting: 2020-09-17T15:50:44.000Z
- Ending: 2020-09-18T15:50:44.000Z
- Census size: 10
- Current block: 5
- Current votes: 0
Waiting for Vochain block 35
Now at Vochain block 6
Now at Vochain block 7
Now at Vochain block 35`

Submitting vote envelopes
Envelope submitted

- Registered:  true
- Block:  36
- Date:  2020-09-17T15:51:06.000Z

This is what we just did:

  • Initialize the wallet with the voter's private key
  • Fetch the vote metadata
  • Wait until startBlock
  • Request a census merkle proof to a random Gateway, proving that the voter's public key matches the census Merkle root
  • Package our choices into an envelope signed with the voter private key (and optionally encrypt it)
  • Submit the envelope using a random Gateway
  • Retrieve the status of the vote

# Process results

If we look at the visualizer or the block explorer we should see votes already submitted.

If the process type was set to encrypted-poll then, results would remain unavailable until the process ends. As our process is an open poll, however, we can ask for the results in real time:

import { getResultsDigest } from "dvote-js/dist/api/vote"

async function fetchResults() {
    const { questions } = await getResultsDigest(processId, pool)

    console.log("Process results", questions)

After all users have voted, the visualizer shows:

Process results

However, if you can't wait for an encrypted process to end later or you simply want to stop vote submissions, there's a trick you can use. This will change in the near future, but for now you can cancel the rest of the lifespan of a process, if needed. The scrutiny will begin a few seconds later.

import { isCanceled, cancelProcess } from "dvote-js/dist/api/vote"

async function forceEndingProcess() {
    // Already canceled?
    const canceled = await isCanceled(processId, pool)
    if (canceled) return console.log("Process already canceled")

    // Already ended?
    const processMeta = await getVoteMetadata(processId, pool)
    const currentBlock = await getBlockHeight(pool)
    if (currentBlock >= (processMeta.startBlock + processMeta.numberOfBlocks)) return console.log("Process already ended")

    console.log("Canceling process", processId)
    await cancelProcess(processId, entityWallet, pool)

Congratulations! You just conducted an election!

A recap of the the examples featured on the article are available on this repository:

https://github.com/vocdoni/tutorials/tree/master/voting-as-a-service (opens new window)

Last Updated: 10/27/2021, 10:11:39 PM