How end-to-end verifiable online voting actually works... and why you can trust it
Summary:
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:
- Cast as intended – the system encrypted your real vote.
- Recorded as cast – your encrypted vote was submitted and stored as-is.
- Counted as recorded – your vote made it into the final tally and was counted correctly.
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.
2. Recorded as cast
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.
3. Counted as recorded
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.
Real-world election processes
In an actual election, this process is backed by a clear set of roles and safeguards.
- Election officials prepare the ballot and designate trustees, who each hold a portion of the cryptographic keys used to decrypt the final tally. No single person can do it alone. Decryption requires cooperation, usually a quorum.
- Voters authenticate using credentials distributed securely, typically via channels they already trust such as email, SMS, or post. Once logged in, they vote through a device-agnostic, accessible interface designed for usability across different devices and needs.
- After voting ends, the trustees come together, either virtually or in person, to decrypt the final tally and generate public proofs that the count is correct. The result isn’t just announced. It is demonstrated.
Why end-to-end verifiability matters
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.
How can you trust online voting?
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.
Key takeaways
- End-to-end verifiable voting systems enable voters to verify their own vote without exposing how they voted.
- These systems provide three guarantees: cast as intended, recorded as cast, and counted as recorded.
- Cryptographic methods like ballot challenges, receipts, and zero-knowledge proofs underpin the process.
- The model shifts trust from institutions to publicly verifiable evidence.
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.
