What Happened to Swiss E-voting Pilot Decryption Failure?
The Swiss e-voting system faced a major setback in March 2019 when critical cryptographic vulnerabilities were discovered, leading to the suspension of trials and a redesign of the system. After a period of development and rigorous testing, a new fully verifiable system by Swiss Post was reintroduced for pilot programs in several cantons. However, in March 2026, a local decryption failure in the Basel-Stadt pilot once again highlighted the challenges of secure electronic voting.
Quick Answer
The 'Swiss E-voting Pilot Decryption Failure' refers primarily to a critical incident in March 2019 where researchers uncovered severe cryptographic flaws in the then-active e-voting system, leading to its suspension. Following a comprehensive redesign and the implementation of a new, fully verifiable system by Swiss Post, pilot trials resumed in several cantons. Most recently, in March 2026, the Basel-Stadt e-voting pilot experienced a decryption failure, rendering 2,048 votes unreadable, though authorities stated the core Swiss Post system was not at fault. The Basel-Stadt pilot is suspended until December 2026, while other cantons continue their trials with the Swiss Post system, with licenses extended until June 2027.
📊Key Facts
📅Complete Timeline14 events
Canton Geneva withdraws its e-voting system
Canton Geneva discontinues its e-voting system due to high costs, reducing the number of active systems in Switzerland.
Public Intrusion Test (PIT) launched for Swiss Post system
Swiss Post launches a public intrusion test, inviting ethical hackers and researchers to find vulnerabilities in its e-voting system with rewards offered for discoveries.
Critical flaw allowing vote manipulation discovered
Researchers Sarah Jamie Lewis, Olivier Pereira, and Vanessa Teague reveal a critical cryptographic flaw in the Swiss Post/Scytl system that could allow attackers to replace legitimate votes with fraudulent ones.
Second flaw found: changing valid votes to nonsense
The same research team uncovers a second vulnerability related to decryption proofs, which could allow a malicious authority to change valid votes into unreadable data.
Swiss Post suspends its e-voting system
Due to the discovered security concerns, Swiss Post decides to temporarily suspend its e-voting system, halting its use in upcoming elections.
Federal Council suspends permanent e-voting plans and mandates redesign
The Swiss Federal Council decides to suspend efforts to enshrine e-voting as an official voting channel and commissions a redesign of the trial phase, acknowledging the need for improved security.
Federal Council launches redesign of e-voting trials
The Federal Council announces a redesign of e-voting trials, focusing on fully verifiable systems, increased transparency, and closer cooperation with independent experts.
New legal basis for e-voting trials comes into force
Revised ordinances on political rights and electronic voting come into effect, providing a new legal framework for the resumption of e-voting trials.
Cantons resume e-voting trials with new Swiss Post system
Basel-Stadt, St. Gallen, and Thurgau resume limited e-voting trials using Swiss Post's new, fully verifiable system.
Canton Graubünden joins e-voting trials
The canton of Graubünden begins its e-voting trials, further expanding the pilot program.
Federal Council extends e-voting trial licenses
The Federal Council extends the basic licenses for e-voting trials in Basel-Stadt, St. Gallen, Graubünden, and Thurgau for another two years, until June 6, 2027.
Swiss Post's public intrusion test finds no critical vulnerabilities
Swiss Post conducts its annual public intrusion test, where ethical hackers attempt to find flaws in the e-voting system. No security-relevant vulnerabilities are found.
Basel-Stadt e-voting pilot experiences decryption failure
During national referendums, the Basel-Stadt e-voting pilot fails to decrypt 2,048 votes, rendering them unreadable due to an issue with local access infrastructure.
Basel-Stadt suspends pilot; Federal Chancellery confirms core system unaffected
Basel-Stadt suspends its e-voting pilot until December 2026 and launches a criminal investigation. The Federal Chancellery clarifies that the core Swiss Post e-voting system used by other cantons was not affected.
🔍Deep Dive Analysis
The journey of Swiss e-voting has been marked by ambitious goals and significant technical challenges. The initial major incident, often referred to as the 'decryption failure' or 'security flaw' period, occurred in March 2019. During a public intrusion test, a team of researchers, including Sarah Jamie Lewis, Olivier Pereira, and Vanessa Teague, uncovered critical cryptographic vulnerabilities in the e-voting system developed by Swiss Post and Spanish technology maker Scytl. These flaws were severe, with one allowing for the manipulation of votes and another enabling a cheating authority to change valid votes into unreadable 'nonsense' without detection, compromising the system's 'complete verifiability' claims.
The discovery of these vulnerabilities led to immediate and significant consequences. Swiss Post suspended its e-voting system, and in June 2019, the Federal Council decided to suspend efforts to establish e-voting as a permanent voting channel, mandating a redesign of the trial phase. This period saw a moratorium on e-voting, with a focus on developing more robust and transparent systems. A people's initiative for a five-year moratorium was launched but later suspended in June 2020 due to the COVID-19 pandemic, though its aims were partially met as authorities acknowledged flaws and agreed to a moratorium.
In December 2020, the Federal Council launched a redesign of e-voting trials, emphasizing the use of 'fully verifiable' systems, increased transparency, and closer cooperation with independent experts. A new legal framework came into effect in July 2022, paving the way for renewed trials. Swiss Post developed a new e-voting system with complete verifiability, which underwent extensive public intrusion tests and audits. These tests, involving thousands of ethical hackers, identified only minor issues, boosting confidence in the redesigned system.
By June 2023, cantons Basel-Stadt, St. Gallen, and Thurgau resumed e-voting trials, with Graubünden joining in March 2024. The Federal Council extended the basic licenses for these trials until June 2027, indicating a cautious but continued commitment to e-voting. However, the system faced another significant incident on March 7-8, 2026, when the Basel-Stadt e-voting pilot experienced a decryption failure. Approximately 2,048 votes, primarily from Swiss citizens living abroad and people with disabilities, could not be opened using the provided decryption codes, despite multiple attempts by IT experts.
The Basel-Stadt authorities emphasized that the error was specific to their access infrastructure and not the underlying Swiss Post e-voting system, which was reportedly unaffected in other cantons. Nevertheless, the incident led to the suspension of the Basel-Stadt pilot until December 2026 and prompted a criminal investigation by the public prosecutor's office. This latest event underscores the ongoing challenges in implementing secure and trustworthy electronic voting, even with redesigned systems and continuous scrutiny. The Organisation of the Swiss Abroad continues to advocate for reliable e-voting to ensure better participation for the diaspora.
What If...?
Explore alternate histories. What if Swiss E-voting Pilot Decryption Failure made different choices?