Paper 2025/506 Original: eprint.iacr.org/2025/506 ↗

On the Estonian Internet Voting System, IVXV, SoK and Suggestions

Abstract

The Estonian i-voting experience, since 2005, is probably the richest to analyze; yet it still holds a collection of noteworthy threats as stated in the 2025 Estonian Academy of Science (Cyber Security Committee) report. This paper first gathers vulnerabilities discovered and improvements/fixes introduced to the Estonian i-voting system, IVXV, in the years 2023-2025; then presents a thorough analysis of its status, as of October 2025 version, with exploits pointed out and solutions suggested. In our review, we shade some light on automated formal verification research attempts that went unnoticed by the Estonian research community; we also notice that, since 2024, forcing a time gap between multiple votes could prevent Perreira revoting attack for verifying voters. Although the problem of not authenticating the Voting Application (VA) is not new and was discussed in the Estonian report, we warn of possible threats that have been missed. We show how new technologies like anonymous online auctions between candidates and hardware execution attests for conditional payment can be used to orchestrate an automated large-scale attack where an encrypted vote is generated online without the vote sellers even knowing who they’re voting for; adding fresh randomness to each ballot enables the attack to pass duplicate ballots anomaly check if existed. We agree that compromised voters’ credentials is a known threat to all i-voting systems; however, it only gets severe in the Estonian case where any application can cast a vote. Finally, we discuss the approaching quantum threat and recommend protecting election data from the possible HNDL (Harvest Now Decrypt Later) privacy threat by encrypting ballots, while residing on the system servers, using a quantum secure symmetric key algorithm (AES). The appendices contain also two suggested solutions for insiders' threat.