The New South Wales Electoral Commission (NSWEC) has released a statement in response to a group of researchers detailing a second flaw in the electronic voting system it uses, saying it is confident it has not been affected.
Security researchers Sarah Jamie Lewis, Olivier Pereira, and Vanessa Teague described the new flaw that could allow vote tampering in the Swiss Internet voting system, which is the same system used by NSWEC.
The researchers, who earlier this month found a flaw in the proof the SwissPost system uses to prevent electoral fraud, have discovered another method that could be exploited to result in a tampered election outcome.
"We have recently discovered a second, independent method by which a proof mechanism in sVote could be subverted to prove an election outcome that has actually been manipulated," they wrote.
The second flaw follows the first, which was essentially a trapdoor -- a flaw in the mixnet component that shuffles votes in an effort to remove the ability to link votes to individual electors.
According to the researchers, the SwissPost system offers one form of verifiability, called complete verifiability, which means that any manipulation should be detectable unless all but one part of the system colludes to cheat.
"In the SwissPost system, encrypted electronic votes are shuffled to protect individual vote privacy. Each server shuffling votes is supposed to prove that the set of input votes it gets correspond exactly to the differently-encrypted votes it outputs," they continued.
The next step after shuffling, the researchers explained, is decrypting the votes. But the cryptographic construct in place for the Swissvote System, a zero knowledge proof, has now been highlighted by the researchers as "not sound".
"Our research has found that this proof is not sound. It's possible to generate a proof that passes verification, but changes the contents of the encrypted vote," they said. "It's a little like leaving the ballot box observable all through polling day, yet somehow managing to slip different votes into the count."
After hearing of the second flaw, NSWEC said its system has not been affected.
"Based on its assessment of the information supplied by these academics, the NSW Electoral Commission is confident that the new issue they describe in the Swiss Post system is not relevant to the iVote system," the state government entity said.
It also previously claimed it was unaffected by the first flaw because its mixnet was not connected to any systems and was "securely housed" at the NSWEC.
NSWEC said a patch addressing the first issue has been installed.
The Commission said on Saturday that over 207,000 people had used iVote for the NSW state election.
The researchers took the opportunity to highlight that it only became aware of the issues potentially affecting the iVote system thanks to the code used by the Swiss system being made available.
"It's lucky that a problem in iVote could be discovered by inspecting the Swiss code, because the iVote code is available only under very restrictive terms that would not have allowed us to analyse the code and publish our findings promptly," they wrote.
"Open, public review is important even for systems that are intended to be verifiable, because the voters and candidates need to be convinced that it will not seem to verify something that is wrong. Otherwise, the risk of undetectable electoral fraud remains, because of the risk that the verification mechanism itself might be manipulated."
Teague later on Monday highlighted that it is illegal for a voter registered in NSW to be educated on how their voting system works.
"I wonder how many NSW voters realise it's a crime for someone to tell them the details of how their voting system works. Do you go to jail for publishing the Swiss code if it happens to overlap with iVote? This law serves vendor interests at the expense of NSW democracy," she wrote in a tweet.
The researcher pointed to a the NSW Electoral Act 2017, under section 159: Secrecy relating to technology assisted voting that states:
A person must not disclose to any other person any source code or other computer software that relates to technology assisted voting under the approved procedures, except in accordance with the approved procedures or in accordance with any arrangement entered into by the person with the Electoral Commissioner.
Maximum penalty: 200 penalty units or imprisonment for 2 years, or both.
In 2015, Teague was part of a team that discovered iVote was susceptible to the FREAK vulnerability.
Updated Monday March 25 at 4.50pm AEDT: Added tweet from Vanessa Teague and detail from the NSW Electoral Act.
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