By now there is overwhelming evidence that today’s paperless computer-based voting technologies have such serious security and reliability problems that we should not be using them. Computers can’t do the job by themselves; but what role should they play in voting?

It’s tempting to eliminate computers entirely, returning to old-fashioned paper voting, but I think this is a mistake. Paper has an important role, as I’ll describe below, but paper systems are subject to well-known problems such as ballot-box stuffing and chain voting, as well as other user-interface and logistical challenges.

Security does require some role for paper. Each vote must be recorded in a manner that is directly verified by the voter. And the system must be software-independent, meaning that its accuracy cannot rely on the correct functioning of any software system. Today’s paperless e-voting systems satisfy neither requirement, and the only practical way to meet the requirements is to use paper.

The proper role for computers, then, is to backstop the paper system, to improve it. What we want is not a computerized voting system, but a computer-augmented one.

This mindset changes how we think about the role of computers. Instead of trying to make computers do everything, we will look instead for weaknesses and gaps in the paper system, and ask how computers can plug them.

There are two main ways computers can help. The first is in helping voters cast their votes. Computers can check for errors in ballots, for example by detecting an invalid ballot while the voter is still in a position to fix it. Computers can present the ballot in audio format for the blind or illiterate, or in multiple languages. (Of course, badly designed computer interfaces can do harm, so we have to be careful.) There must be a voter-verified paper record at the end of the vote-casting process, but computers, used correctly, can help voters create and validate that record, by acting as ballot-marking devices or as scanners to help voters spot mismarked ballots.

The second way computers can help is by improving security. Usually the e-voting security debate is about how to keep computers from making security too much worse than it was before. Given the design of today’s e-voting systems, this is appropriate – just bringing these systems up to the level of security and reliability in (say) the Xbox and Wii game consoles would be nice. Even in a computer-augmented system, we’ll need to do a better job of vetting the computers’ design – if a job is worth doing with a computer, it’s worth doing correctly.

But once we adopt the mindset of augmenting a paper-based system, security looks less like a problem and more like an opportunity. We can look for the security weaknesses of paper-based systems, and ask how computers can help to address them. For example, paper-based systems are subject to ballot-box stuffing – how can computers reduce this risk?

Surprisingly, the designs of current e-voting technologies, even the ones with paper trails, don’t do all they can to compensate for the weaknesses of paper. For example, the current systems I’ve seen keep electronic records that are subject to straightforward post-election tampering. Researchers have studied approaches to this problem, but as far as I know none are used in practice.

In future posts, we’ll discuss design ideas for computer-augmented voting.

The technical team commissioned by the State of Florida to study the technology used in the ill-fated Sarasota election has released its report. (Background: on the Sarasota election problems; on the study.)

One revelation from the study is that the iVotronic touch-screen voting machines are terribly insecure. The machines are apparently susceptible to viruses, and there are many bugs a virus could exploit to gain entry or spread:

We found many instances of [exploitable buffer overflow bugs]. Misplaced trust in the election definition file can be found throughout the iVotronic software. We found a number of buffer overruns of this type. The software also contains array out-of-bounds errors, integer overflow vulnerabilities, and other security holes. [page 57]

The equation is simple: sloppy software + removable storage = virus vulnerability. We saw the same thing with the Diebold touchscreen voting system.

Another example of poor security is in the passwords that protect crucial operations such as configuring the voting machine and modifying its software. There are separate passwords for different operations, but the system has a single backdoor that allows all of the passwords to be bypassed by an adversary who can learn or guess a one-byte secret, which is easily guessed since there are only 256 possibilities. (p. 67) For example, an attacker who gets private access to the machine for just a few minutes can apparently use the backdoor to install malicious software onto a machine.

Though the machines’ security is poor and needs to be fixed before it is used in another election, I agree with the study team that the undervotes were almost certainly not caused by a security attack. The reason is simple: only a brainless attacker would cause undervotes. An attack that switched votes from one candidate to another would be more effective and much harder to detect.

So if it wasn’t a security attack, what was the cause of the undervotes?

Experience teaches that systems that are insecure tend to be unreliable as well – they tend to go wrong on their own even if nobody is attacking them. Code that is laced with buffer overruns, array out-of-bounds errors, integer overflow errors, and the like tends to be flaky. Sporadic undervotes are the kind of behavior you would expect to see from a flaky voting technology.

The study claims to have ruled out reliability problems as a cause of the undervotes, but their evidence on this point is weak, and I think the jury is still out on whether voting machine malfunctions could be a significant cause of the undervotes. I’ll explain why, in more detail, in the next post.

By now it should be clear that Diebold’s AccuVote-TS electronic voting machines have lousy security. Our study last fall showed that malicious software running on the machines can invisibly alter votes, and that this software can be installed in under a minute by inserting a new memory card into the side of the machine. The last line of defense against such attacks is a cheap lock covering the memory card door. Our video shows that the lock can be picked in seconds, and, infamously, it can also be opened with a key that is widely sold for use in hotel minibars and jukeboxes.

(Some polling places cover the memory card with tamper evident seals, but these provide little real security. In practice, the seals are often ignored or accidentally broken. If broken seals are taken seriously and affected machines are taken offline for inspection, an attacker could launch a cheap denial-of-service attack by going around breaking the seals on election day.)

According to published reports, nearly all the machines deployed around the country use the exact same key. Up to this point we’ve been careful not to say precisely which key or show the particular pattern of the cuts. The shape of a key is like a password – it only provides security if you keep it secret from the bad guys. We’ve tried to keep the shape secret so as not to make an attacker’s job even marginally easier, and you would expect a security-conscious vendor to do the same.

Not Diebold. Ross Kinard of SploitCast wrote to me last month to point out that Diebold offers the key for sale on their web site. Of course, they won’t sell it to just anybody – only Diebold account holders can order it online. However, as Ross observed, Diebold’s online store shows a detailed photograph of the key.

Here is a copy of the page. The original showed the entire key, but we have blacked out the compromising part.

Could an attacker create a working key from the photograph? Ross decided to find out. Here’s what he did:

I bought three blank keys from Ace. Then a drill vise and three cabinet locks that used a different type of key from Lowes. I hoped that the spacing and depths on the cabinet locks’ keys would be similar to those on the voting machine key. With some files I had I then made three keys to look like the key in the picture.

Ross sent me his three homemade keys, and, amazingly, two of them can open the locks on the Diebold machine we used in our study!

This video shows one of Ross’s keys opening the lock on the memory card door:

Ross says he has tried repeatedly to bring this to Diebold’s attention over the past month. However, at the time of this posting, the image was still on their site.

Security experts advocate designing systems with “defense in depth,” multiple layers of barriers against attack. The Diebold electronic voting systems, unfortunately, seem to exhibit “weakness in depth.” If one mode of attack is blocked or simply too inconvenient, there always seems to be another waiting to be exposed.

[UPDATE (Jan. 25): As of this morning, the photo of the key is no longer on Diebold’s site.]