November 24, 2024

Posts Comments

Internet Voting: How Far Can We Go Safely?

June 5, 2009 by

Yesterday I chaired an interesting panel on Internet Voting at CFP. Participants included Amy Bjelland and Craig Stender (State of Arizona), Susan Dzieduszycka-Suinat (Overseas Vote Foundation) Avi Rubin (Johns Hopkins), and Alec Yasinsac (Univ. of South Alabama). Thanks to David Bruggeman and Cameron Wilson at USACM for setting up the panel.

Nobody advocated a full-on web voting system that would allow voting from any web browser. Instead, the emphasis was on more modest steps, aimed specifically at overseas voters. Overseas voters are a good target population, because there aren’t too many of them — making experimentation less risky — and because vote-by-mail serves them poorly.

Discussion focused on two types of systems: voting kiosks, and Internet transmission of absentee ballots.

A voting kiosk is a computer-based system, running carefully configured software, that is set up in a securable location overseas. Voters come to this location, authenticate themselves, and vote just as they would in a polling place back home. A good kiosk system keeps an electronic record, which is transmitted securely across the Internet to voting officials in the voter’s home jurisdiction. It also keeps a paper record, verifiable by the voter, which is sent back to voting officials after the elections, enabling a post-election audit. A kiosk can use optical-scan technology or it can be a touch-screen machine with a paper trail — essentially it’s a standard voting system with a paper trail, connected to home across the Internet. If the engineering is done right, if the home system that receives the electronic ballots is walled off from the central vote-tabulating system, and if appropriate post-election auditing is done, this system can be secure enough to use. All of the panelists agreed that this type of system is worth trying, at least as a pilot test.

The other approach is use ordinary absentee ballots, but to distribute them and allow voters to return them online. A voter goes to a web site and downloads a file containing an absentee ballot and a cover sheet. After printing out the file, the voter fills out the cover sheet (giving his name and other information) and the ballot. He scans the cover sheet and ballot, and uploads the scan to a web site. Election officials collect and print the resulting file, and treat the printout like an ordinary absentee ballot.

Kevin Poulsen and Eric Rescorla criticize the security of this system, and for good reason. Internet distribution of blank ballots can be secure enough, if done very carefully, but returning filled-out ballots from an ordinary computer and browser is risky. Eric summarizes the risks:

We have integrity issues here as well: as Poulsen suggests (and quotes Rubin as suggesting), there are a number of ways for things to go wrong here: an attacker could subvert your computer and have it modify the ballots before sending them; you could get phished and the phisher could modify your ballot appropriately before passing it on to the central site. Finally, the attacker could subvert the central server and modify the ballots before they are printed out.

Despite the risks, systems of this sort are moving forward in various places. Arizona has one, which Amy and Craig demonstrated for the panel’s audience, and the Overseas Vote Foundation has one as well.

Why is this less-secure alternative getting more traction than kiosk-based systems? Partly it’s due to the convenience of being able to vote from anywhere (with a Net connection) instead of having to visit a kiosk location. That’s understandable. But another part of the reason seems to be that people don’t realize what can go wrong, and how often things actually do go wrong, in online interactions.

In the end, there was a lot of agreement among the panelists — a rare occurrence in public e-voting discussions — but disagreement remained about how far we can go safely. For overseas voters at least, the gap between what is convenient and what can be made safe is smaller than it is elsewhere, but that gap does still exist.

Filed Under: Uncategorized Tagged With: ,

Acceptance rates at security conferences

April 30, 2009 by

How competitive are security research conferences? Several people have been tracking this information. Mihai Christodorescu has a nice chart of acceptance and submission rates over time. The most recent data point we have is the 2009 Usenix Security Symposium, which accepted 26 of 176 submissions (a 14.8% acceptance ratio, consistent with recent years). Acceptance rates like that, at top security conferences, are now pretty much the norm.

With its deadline one week ago, ACM CCS 2009 got 317 submissions this year (up from 274 last year, and approx. 300 the year before) and ESORICS 2009, with a submission deadline last Friday night, got 222 submissions (up from about 170 last year).

Think about that: right now there are over 500 research manuscripts in the field of computer security fighting it out, and maybe 15-20% of those will get accepted. (And that’s not counting research in cryptography, or the security-relevant papers that regularly appear in the literature on operating systems, programming languages, networking, and other fields.) Ten years ago, when I first began as an assistant professor, there would be half as many papers submitted. At the time, I grumbled that we had too many security conferences and that the quality of the proceedings suffered. Well, that problem seems mostly resolved, except rather than having half as many conferences, we now have a research community that’s apparently twice as large. I suppose that’s a good thing, although there are several structural problems that we, the academic security community, really need to address.

  • What are we supposed to do with the papers that are rejected, resubmitted, rejected again, and so on? Clearly, some of this work has value and never gets seen. Should we make greater use of the arXiv.org pre-print service? There’s a crypto and computer security section, but it’s not heavily used. Alternatively, we could join on on the IACR Cryptology ePrint Archive or create our own.
  • Should we try to make the conference reviewing systems more integrated across conferences, such that PC comments from one conference show up in a subsequent conference, and the subsequent PC can see both drafts of the paper? This would make conference reviewing somewhat more like journal reviewing, providing a measure of consistency from one conference to the next.
  • Low acceptance ratios don’t necessarily achieve higher quality proceedings. There’s a distinctive problem that occurs when a conference has a huge PC and only three of them review any given paper. Great papers still get in and garbage papers are still rejected, but the outcomes for papers “on the bubble” becomes more volatile, depending on whether those papers get the right reviewers. Asking PC members to do more reviews is just going to lower the quality of the reviews or discourage people from accepting positions on PCs. Adding additional PC members could help, but it also can be unwieldy to manage a large PC, and there will be even more volatility.
  • Do we need another major annual computer security conference? Should more workshops be willing to take conference-length submissions? Or should our conferences raise their acceptance rates up to something like 25%, even if that means compressed presentations and the end of printed proceedings? How much “good” work is out there, if only there was a venue in which to print it?

About the only one of these ideas I don’t like is adding another top-level security conference. Otherwise, we could well do all-of-the-above, and that would be a good thing. I’m particularly curious if arbitrarily increasing the acceptance rates would resolve some of the volatility issues on the bubble. I think I’d rather that our conferences err on the side of taking the occasional bad/broken/flawed paper rather than rejecting the occasional good-but-misunderstood paper.

Maybe we just need to harness the power of our graduate students. When you give a grad student a paper to review, they treat it like a treasure and write a detailed review, even if they may not be the greatest expert in the field. Conversely, when you give an overworked professor a paper to review, they blast through it, because they don’t have the time to spend a full day on any given paper. Well, it’s not like our grad students have anything better to be doing. But does the additional time they can spend per paper make up for the relative lack of experience and perspective? Can they make good accept-or-reject judgements for papers on the bubble?

For additional thoughts on this topic, check out Matt Welsh’s thoughts on scaling systems conferences. He argues that there’s a real disparity between the top programs / labs and everybody else and that it’s worthwhile to take steps to fix this. (I’ll argue that security conferences don’t seem to have this particular problem.) He also points out what I think is the deeper problem, which is that hotshot grad students must get themselves a long list of publications to have a crack at a decent faculty job. This was emphatically not the case ten years ago.

See also, Birman and Schneider’s CACM article (behind a paywall, unless your university has a site license). They argue that the focus on short, incremental results is harming our field’s ability to have impact. They suggest improving the standing of journals in the tenure game and they suggest disincentivizing people from submitting junk / preliminary papers by creating something of a short-cut reject that gets little or no feedback and also, by virtue of the conferences not being blind-review, creates the possibility that a rejected paper could harm the submitter’s reputation.

Filed Under: Uncategorized Tagged With: ,

Fingerprinting Blank Paper Using Commodity Scanners

March 13, 2009 by

Today Will Clarkson, Tim Weyrich, Adam Finkelstein, Nadia Heninger, Alex Halderman and I released a paper, Fingerprinting Blank Paper Using Commodity Scanners. The paper will appear in the Proceedings of the IEEE Symposium on Security and Privacy, in May 2009.

Here’s the paper’s abstract:

This paper presents a novel technique for authenticating physical documents based on random, naturally occurring imperfections in paper texture. We introduce a new method for measuring the three-dimensional surface of a page using only a commodity scanner and without modifying the document in any way. From this physical feature, we generate a concise fingerprint that uniquely identifies the document. Our technique is secure against counterfeiting and robust to harsh handling; it can be used even before any content is printed on a page. It has a wide range of applications, including detecting forged currency and tickets, authenticating passports, and halting counterfeit goods. Document identification could also be applied maliciously to de-anonymize printed surveys and to compromise the secrecy of paper ballots.

Viewed under a microscope, an ordinary piece of paper looks like this:

The microscope clearly shows individual wood fibers, laid down in a pattern that is unique to this piece of paper.

If you scan a piece of paper on an ordinary desktop scanner, it just looks white. But pick a small area of the paper, digitally enhance the contrast and expand the image, and you see something like this:

The light and dark areas you see are due to two factors: inherent color variation in the surface, and partial shadows cast by fibers in the paper surface. If you rotate the paper and scan again, the inherent color at each point will be the same, but the shadows will be different because the scanner’s light source will strike the paper from a different angle. These differences allow us to map out the tiny hills and valleys on the surface of the paper.

Here is a visualization of surface shape from one of our experiments:

This part of the paper had the word “sum” printed on it. You can clearly see the raised areas where toner was applied to the paper to make the letters. Around the letters you can see the background texture of the paper.

Computing the surface texture is only one part of the job. From the texture, you want to compute a concise, secure “fingerprint” which can survive ordinary wear and tear on the paper, such as crumpling, scribbling or printing, and moisture. You also want to understand how secure the technology will be in various applications. Our full paper addresses these issues too. The bottom-line result is a sort of unique fingerprint for each piece of paper, which can be determined using an ordinary desktop scanner.

For more information, see the project website or our research paper.

Filed Under: Uncategorized Tagged With: , , ,

NJ Voting-machine trial update

February 26, 2009 by

Earlier this month I testified in Gusciora v. Corzine, the trial in which the plaintiffs argue that New Jersey’s voting machines (Sequoia AVC Advantage) can’t be trusted to count the votes, because they’re so easily hacked to make them cheat.

I’ve previously written about the conclusions of my expert report: in 7 minutes you can replace the ROM and make the machine cheat in every future election, and there’s no practical way for the State to detect cheating machines (in part because there’s no voter-verified paper ballot).

The trial started on January 27, 2009 and I testified for four and a half days. I testified that the AVC Advantage can be hacked by replacing its ROM, or by replacing its Z80 processor chip, so that it steals votes undetectably. I testified that fraudulent firmware can also be installed into the audio-voting daughterboard by a virus carried through audio-ballot cartridges. I testified about many other things as well.

Finally, I testified about the accuracy of the Sequoia AVC Advantage. I believe that the most significant source of inaccuracy is its vulnerability to hacking. There’s no practical means of testing whether the machine has been hacked, and certainly the State of New Jersey does not even attempt to test. If we could somehow know that the machine has not been hacked, then (as I testified) I believe the most significant _other_ inaccuracy of the AVC Advantage is that it does not give adequate feedback to voters and pollworkers about whether a vote has been recorded. This can lead to a voter’s ballot not being counted at all; or a voter’s ballot counting two or three times (without fraudulent intent). I believe that this error may be on the order of 1% or more, but I was not able to measure it in my study because it involves user-interface interaction with real people.

In the hypothetical case that the AVC Advantage has not been hacked, I believe this user-interface source of perhaps 1% inaccuracy would be very troubling, but (in my opinion) is not the main reason to disqualify it from use in elections. The AVC Advantage should be disqualified for the simple reason that it can be easily hacked to cheat, and there’s no practical method that will be sure of catching this hack.

Security seals. When I examined the State’s Sequoia AVC Advantage voting machines in July 2008, they had no security seals preventing ROM replacement. I demonstrated on video (which we played in Court in Jan/Feb 2009) that in 7 minutes I could pick the lock, unscrew some screws, replace the ROM with one that cheats, replace the screws, and lock the door.

In September 2008, after the State read my expert report, they installed four kinds of physical security seals on the AVC Advantage. These seals were present during the November 2008 election. On December 1, I sent to the Court (and to the State) a supplemental expert report (with video) showing how I could defeat all of these seals.

In November/December the State informed the Court that they were changing to four new seals. On December 30, 2008 the State Director of Elections, Mr. Robert Giles, demonstrated to me the installation of these seals onto the AVC Advantage voting machine and gave me samples. He installed quite a few seals (of these four different kinds, but some of them in multiple places) on the machine.

On January 27, 2009 I sent to the Court (and to the State) a supplemental expert report showing how I could defeat all those new seals. On February 5th, as part of my trial testimony I demonstrated for the Court the principles and methods by which each of those seals could be defeated.

On cross-examination, the State defendants invited me to demonstrate, on an actual Sequoia AVC Advantage voting machine in the courtroom, the removal of all the seals, replacement of the ROM, and replacement of all the seals leaving no evidence of tampering. I then did so, carefully and slowly; it took 47 minutes. As I testified, someone with more practice (and without a judge and 7 lawyers watching) would do it much faster.

Filed Under: Other Topics, Privacy & Security Tagged With: ,

New Internet? No Thanks.

February 16, 2009 by

Yesterday’s New York Times ran a piece, “Do We Need a New Internet?” suggesting that the Internet has too many security problems and should therefore be rebuilt.

The piece has been widely criticized in the technical blogosphere, so there’s no need for me to pile on. Anyway, I have already written about the redesign-the-Net meme. (See Internet So Crowded, Nobody Goes There Anymore.)

But I do want to discuss two widespread misconceptions that found their way into the Times piece.

First is the notion that today’s security problems are caused by weaknesses in the network itself. In fact, the vast majority of our problems occur on, and are caused by weaknesses in, the endpoint devices: computers, mobile phones, and other widgets that connect to the Net. The problem is not that the Net is broken or malfunctioning, it’s that the endpoint devices are misbehaving — so the best solution is to secure the endpoint devices. To borrow an analogy from Gene Spafford, if people are getting mugged at bus stops, the solution is not to buy armored buses.

(Of course, there are some security issues with the network itself, such as vulnerability of routing protocols and DNS. We should work on fixing those. But they aren’t the problems people normally complain about — and they aren’t the ones mentioned in the Times piece.)

The second misconception is that the founders of the Internet had no plan for protecting against the security attacks we see today. Actually they did have a plan which was simple and, if executed flawlessly, would have been effective. The plan was that endpoint devices would not have remotely exploitable bugs.

This plan was plausible, but it turned out to be much harder to execute than the founders could have foreseen. It has become increasingly clear over time that developing complex Net-enabled software without exploitable bugs is well beyond the state of the art. The founders’ plan is not working perfectly. Maybe we need a new plan, or maybe we need to execute the original plan better, or maybe we should just muddle through. But let’s not forget that there was a plan, and it was reasonable in light of what was known at the time.

As I have said before, the Internet is important enough that it’s worthwhile having people think about how it might be redesigned, or how it might have been designed differently in the first place. The Net, like any large human-built institution, is far from perfect — but that doesn’t mean that we would be better off tearing it down and starting over.

Filed Under: Uncategorized Tagged With: ,