Local police have raided the home of an Argentinian programmer who reported a flaw in an e-voting system that was used this weekend for local elections in Buenos Aires. The police took away all of his devices that could store data. According to a report in the newspaper La Nación, Joaquín Sorianello had told the company MSA, which makes the Vot.ar e-voting system, about the problem after he discovered information on the protected Twitter account @FraudeVotar. This revealed that the SSL certificates used to encrypt transmissions between the voting stations and the central election office could be easily downloaded, potentially allowing fraudulent figures to be sent.

Sorianello told La Nación that he was only a programmer, not a hacker: "If I'd wanted to hack [the system], or do some damage, I wouldn't have warned the company." He also pointed out that it was the @FraudeVotar account that had published the information, not him. As a result of the police action, he said he was "really scared."

This is the latest in a series of problems for the e-voting system, which is being used in Buenos Aires local elections for the first time. Two weeks ago, some of the source code for the Vot.ar system was posted on GitHub. The company said it was not secret since it had been submitted to the authorities for auditing.

More recently, a group of researchers discovered a weakness in the system that they said could potentially allow a specially crafted e-voting ballot to be counted more than once (full details in Spanish). However, MSA said this would be almost impossible in practice.

It was just hours after newspapers started reporting on this new problem that the police raided the home of Sorianello, although he was not one of the researchers who made the claim. The police haven't yet released any information about the raid.

Despite its use in elections, Vot.ar is not called an e-voting system officially, but an "Electronic Single Ballot." A background document by the Argentinian Twitter user @sebasauerbraten claims: "This was done as a measure to avoid going through the local legislative branch as local regulations require that any 'electronic voting system' go through the Buenos Aires City Legislature. This is considered by many suspicious."

Concerns about the way the e-voting system has been introduced are shared by the Argentinian digital rights group Fundación Vía Libre, which has been following this issue for many years, calling e-voting a "solution in search of problems." In March 2009 it published a free e-book (in Spanish) entitled "Electronic voting: The risks of an illusion." The book contained a foreword by Richard Stallman, who wrote: "Voting with computers opens a big door to fraud." He goes on to say that even using free software is not enough to avoid this problem, and concludes: "The only reliable system is to vote with paper."

The latest experience in Buenos Aires seems to confirm the difficulties of using e-voting. Earlier today, the Argentinian site La Política Online reported that 532 polling stations were unable to transmit their results electronically to the central electoral office, and had to be transported there physically for the 184,000 votes involved to be included in the final result. As the article points out, although this failure won't change the outcome of the election for the head of local government in Buenos Aires, it will make a difference to the allocation of seats in the legislature and community boards.

Updated, July 7 @ 12:05 BST: It now emerges that on July 3 a judge ordered Argentina's National Authority for Information and Communication Technology to block local access to five pages on the justpaste.it site that were related to the Buenos Aires elections. Beatriz Busaniche from digital rights group Fundación Vía Libre published a copy of the blocking order on Twitter.

The information contained on those pages is still available elsewhere, and includes details of MSA's leaked SSL certificates, as well as personal data about those involved in running the Buenos Aires polling stations. Some of this is published on the official election site, but other details, such as e-mail addresses and mobile phone numbers, are not, which may be why the judge ordered the pages blocked.