I was pointed at, The Norwegian trial with Internet voting: results and challenges by an attendee at 31C3. The summary states there is no evidence that it increases turnout and concludes,
Nevertheless, at the end of the day, voting in unsupervised environments will always in principle entail risks of this nature. The weight accorded to such risks in decisions regarding the future of internet voting depends on how literally the principle of secret elections is to be taken.
The full text is held at IUSTEL, which appears to be an Iberian Law publication site, and is behind what seems to be a paywall. This page holds an index of papers comprising Special Edition: “Electronic voting and legal dimensions: between the naive complacency and the precipitate rejection. Coordinated byJordiBarrat. I applied for a trial user but the paper is too old, the Special Edition is dated Jul 2013 or outside the trial user conditions. It contains papers about a variety of countries including Venezuela, Mexico, the UK, Spain, Switzerland and France, but not Germany, or anywhere in Eastern Europe, which I consider to be significant.
Following Prof Barrat’s trail takes me to academia.edu and the presumably past conference that he contributed to, called E-Voting the Last Electoral Revolution, his paper was called, “Electronic voting certification procedures. Who should carry out the Technical analysis?”, a very good question.
Typical of the English, we are ignoring the wisdom of the rest of the world.
We should also look at this, http://www.internetvotingproject.com/ an academic collaboration site.