How can we be sure online voting really works? In this article, Victor Hidalgo breaks down how end-to-end verifiable online voting systems provide concrete proof that every vote is cast, recorded, and counted correctly. Voters don’t need to trust the software or election officials when they can verify the process themselves. Through cryptographic tools like ballot challenges, voting receipts, and public proofs, these systems make the entire election process independently auditable. The result is a transparent and trustworthy approach to digital voting built on evidence, not assumptions.
Whenever the topic of online voting comes up, people often ask: “But how do you actually know it works?”
It’s a fair question. So this blog isn’t about the why behind end-to-end verifiable voting (we have one of those already written here!). It’s about the how.
What actually happens under the hood in a system that doesn’t just collect votes, but also proves the outcome is right?
What is end-to-end verifiability?
End-to-end verifiability is a technical standard. It means that from the moment a ballot is cast to the moment the results are tallied, every step of the process is independently verifiable.
Put simply: voters don’t have to trust the vendor, the software, or even the election administrators. They, or independent observers, can verify the process themselves. And if something goes wrong, there’s evidence.
In practice, it comes down to three guarantees:
Let’s walk through how that works.
1. Cast as intended
When you vote online, your selections are encrypted on your device before they’re sent anywhere. That protects your vote in transit, but that’s just the start.
What if malware changed your vote before it was encrypted?
This is where a critical feature comes in: a ballot challenge. At any time, a voter can choose to challenge a ballot before casting it. The system then decrypts that ballot and reveals the selections so the voter can confirm it matches what they picked.
The ability to challenge at any time puts pressure on the system to behave honestly. If the software tried to manipulate votes, it would be caught during these spot checks. Over time, this builds a statistically sound level of trust, based not on hope, but on auditability.
Once you do cast your vote, the system gives you a voting receipt, a short string of data representing your encrypted ballot.
That receipt doesn’t show how you voted, so there’s no privacy risk, but it gives you a way to later confirm that: “Yes, my vote made it into the system.”
While the election is open and after the polls close, the system publishes a public list of all encrypted ballots and their corresponding receipts. You can check yours. So can every other voter. This means missing, altered, or duplicated ballots can’t go unnoticed. The public gets eyes on the public bulletin board.
This is where things get technical!
Once all the encrypted ballots are posted, the system runs a public tally. But it doesn’t just announce the result. It proves it.
Using cryptographic techniques like zero-knowledge proofs, where the system shows that the final count is mathematically consistent with the encrypted ballots. Critically, this is without revealing how individual votes have been cast.
This makes the result independently auditable by anyone. Political parties, watchdog groups, researchers. Anyone with the right tools can check the math.
In an actual election, this process is backed by a clear set of roles and safeguards.
We live in a time when trust in elections can’t be taken for granted. We also live in a time when we can do better.
End-to-end verifiability isn’t just a technology upgrade. It’s a different model for trust. It doesn’t rely on institutions being perfect. It creates a trail of cryptographic evidence anyone can follow.
That matters whether you're voting from abroad, with accessibility needs, or in a low-trust political climate. The same mechanism that ensures integrity also ensures inclusion.
If someone asks, “How can you trust online voting?”, the answer isn’t: “Just trust the system.”
The answer is: You don’t have to. You can verify it for yourself.
End-to-end verifiable voting takes the black box of elections and cracks it open, without compromising privacy, accessibility, or scale. It gives us a system that proves it worked.
Not because someone says it did, but because the math checks out. And that’s what real accountability looks like.
This article is based on insights from a recent webinar with Victor Hidalgo, Global Solutions Manager, Lumi Global. To learn more about how to uphold trust and transparency in digital voting, you can watch the full discussion here.