February 25, 2024

Seals on NJ voting machines, March 2009

During the NJ voting-machines trial, both Roger Johnston and I showed different ways of removing all the seals from voting machines and putting them back without evidence of tampering. The significance of this is that one can then install fraudulent vote-stealing software in the computer.

The State responded by switching seals yet again, right in the middle of the trial! They replaced the white vinyl adhesive-tape seal with a red tape seal that has an extremely soft and sticky adhesive. In addition, they proposed something really wacky: they would squirt superglue into the blue padlock seal and into the security screw cap.

Nothing better illustrates the State’s “band-aid approach, where serious security vulnerabilities can be covered over with ad hoc fixes” (as Roger characterizes it) than this. The superglue will interfere with the ability for election workers to (legitimately) remove the seal to maintain the machine. The superglue will make it more difficult to detect tampering, because it goes on in such a variable way that the inspector doesn’t know what’s supposed to be “normal.” And the extremely soft adhesive on the tape seal is extremely difficult to clean up, when the election worker (legitimately) removes it to maintain the machine. Of course, one must clean up all the old adhesive before resealing the voting machine.

Furthermore, Roger demonstrated for the Court that all these seals can still be defeated, with or without the superglue. Here’s the judge’s summary of his testimony about all these seals:


New Jersey is proposing to add six different kinds of seals in nine different locations to the voting machines. Johnston testified he has never witnessed this many seals applied to a system. At most, Johnston has seen three seals applied to high-level security applications such as nuclear safeguards. According to Johnston, there is recognition among security professionals that the effective use of a seal requires an extensive use protocol. Thus, it becomes impractical to have a large number of seals installed and inspected. He testified that the use of a large number of seals substantially decreases security, because attention cannot be focused for a very long time on any one of the seals, and it requires a great deal more complexity for these seal-use protocols and for training.

For more details and pictures of these seals, see “Seal Regime #4” in this paper.

What an expert on seals has to say

During the New Jersey voting machines lawsuit, the State defendants tried first one set of security seals and then another in their vain attempts to show that the ROM chips containing vote-counting software could be protected against fraudulent replacement. After one or two rounds of this, Plaintiffs engaged Dr. Roger Johnston, an expert on physical security and tamper-indicating seals, to testify about New Jersey’s insecure use of seals.

In his day job, Roger is a scientist at the Argonne National Laboratory, working to secure (among other things) our nation’s shipments of nuclear materials. He has many years of experience in the scientific study of security seals and their use protocols, as well as physical security in general. In this trial he testified in his private capacity, pro bono.

He wrote an expert report in which he analyzed the State’s proposed use of seals to secure voting machines (what I am calling “Seal Regime #2” and “Seal Regime #3”). For some of these seals, he and his team of technicians have much slicker techniques to defeat these seals than I was able to come up with. Roger chooses not to describe the methods in detail, but he has prepared this report for the public.

What I found most instructive about Roger’s report (including in version he has released publicly) is that he explains that you can’t get security just by looking at the individual seal. Instead, you must consider the entire seal use protocol:


Seal use protocols are the formal and informal procedures for choosing, procuring, transporting, storing, securing, assigning, installing, inspecting, removing, and destroying seals. Other components of a seal use protocol include procedures for securely keeping track of seal serial numbers, and the training provided to seal installers and inspectors. The procedures for how to inspect the object or container onto which seals are applied is another aspect of a seal use protocol. Seals and a tamper-detection program are no better than the seal use protocols that are in place.

He explains that inspecting seals for evidence of tampering is not at all straightforward. Inspection often requires removing the seal—for example, when you pull off an adhesive-tape seal that’s been tampered with, it behaves differently than one that’s undisturbed. A thorough inspection may involve comparing the seal with microphotographs of the same seal taken just after it was originally applied.

For each different seal that’s used, one can develop a training program for the seal inspectors. Because the state proposed to use four different kinds of seals, it would need four different sets training materials. Training all the workers who would inspect the State’s 10,000 voting machines would be quite expensive. With all those seals, just the seal inspections themselves would cost over $100,000 per election.

His report also discusses “security culture.”


“Security culture” is the official and unofficial, formal and informal behaviors, attitudes, perceptions, strategies, rules, policies, and practices associated with security. There is a consensus among security experts that a healthy security culture is required for effective security….

A healthy security culture is one in which security is integrated into everyday work, management, planning, thinking, rules, policies, and risk management; where security is considered as a key issue at all employee levels (and not just an afterthought); where security is a proactive, rather than reactive activity; where security measures are carefully defined, and frequently reviewed and studied; where security experts are involved in choosing and reviewing security strategies, practices, and products; where the organization constantly seeks proactively to understand vulnerabilities and provide countermeasures; where input on potential security problems are eagerly considered from any quarter; and where wishful thinking and denial is deliberately avoided in regards to threats, risks, adversaries, vulnerabilities, and the insider threat….

Throughout his deposition … Mr. Giles [Director of the NJ Division of Elections] indicates that he believes good physical security requires a kind of band-aid approach, where serious security vulnerabilities can be covered over with ad hoc fixes or the equivalent of software patches. Nothing could be further from the truth.

Roger Johnston’s testimony about the importance of seal use protocols—as considered separately from the individual seals themselves—made a strong impression on the judge: in the remedy that the Court ordered, seal use protocols as defined by Dr. Johnston played a prominent role.

The trick to defeating tamper-indicating seals

In this post I’ll tell you the trick to defeating physical tamper-evident seals.

When I signed on as an expert witness in the New Jersey voting-machines lawsuit, voting machines in New Jersey used hardly any security seals. The primary issues were in my main areas of expertise: computer science and computer security.

Even so, when the state stuck a bunch of security seals on their voting machines in October 2008, I found that I could easily defeat them. I sent in a supplement expert report to the Court, explaining how.

Soon after I sent in my report about how to defeat all the State’s new seals, in January 2009 the State told the Court that it was abandoning all those seals, and that it had new seals for the voting machines. As before, I obtained samples of these new seals, and went down to my basement to work on them.

In a day or two, I figured out how to defeat all those new seals.

  • The vinyl tamper-indicating tape can be defeated using packing tape, a razor blade, and (optionally) a heat gun.
  • The blue padlock seal can be defeated with a portable drill and a couple of jigs that I made from scrap metal.
  • The security screw cap can be defeated with a $5 cold chisel and a $10 long-nose pliers, each custom ground on my bench grinder.

For details and pictures, see “Seal Regime #3” in this paper.

The main trick is this: just to know that physical seals are, in general, easy to defeat. Once you know that, then it’s just a matter of thinking about how to do it, and having a pile of samples on which to experiment. In fact, the techniques I describe in my paper are not the only way to defeat these seals, or the best way—not even close. These techniques are what an amateur could come up with. But these seal-defeats were good enough to work just fine when I demonstrated them in the courtroom during my testimony, and they would almost certainly not be detected by the kinds of seal-inspection protocols that most states (including New Jersey) use for election equipment.

(In addition, the commenters on my previous post describe a very simple denial-of-service attack on elections: brazenly cut or peel all the seals in sight. Then what will the election officials do? In principle they should throw out the ballots or data covered by those seals. But then what? “Do-overs” of elections are rare and messy. I suspect the most common action in this case is not even to notice anything wrong; and the second most common is to notice it but say nothing. Nobody wants to rock the boat.)

Seals on NJ voting machines, October-December 2008

In my examination of New Jersey’s voting machines, I found that there were no tamper-indicating seals that prevented fiddling with the vote-counting software—just a plastic strap seal on the vote cartridge. And I was rather skeptical whether slapping seals on the machine would really secure the ROMs containing the software. I remembered Avi Rubin’s observations from a couple of years earlier, that I described in a previous post.

A bit of googling turned up this interesting 1996 article:


Vulnerability Assessment of Security Seals
Roger G. Johnston, Ph.D. and Anthony R.E. Garcia
Los Alamos National Laboratory

… We studied 94 different security seals, both passive and electronic, developed either commercially or by the United States Government. Most of these seals are in wide-spread use, including for critical applications. We learned how to defeat all 94 seals using rapid, inexpensive, low-tech methods.

In my expert report, I cited this scientific article to explain that seals would not be a panacea to solve the problems with the voting machine.

Soon after I delivered this report to the Court, the judge held a hearing in which she asked the defendants (the State of New Jersey) how they intended to secure these voting machines against tampering. A few weeks later, the State explained their new system: more seals.

For the November 2008 election, they slapped on three pieces of tape, a wire seal, and a “security screw cap”, in addition to the plastic strap seal that had already been in use. All these seals are in the general categories described by Johnston and Garcia as easy to defeat using “rapid, inexpensive, low-tech methods”.

Up to this point I knew in theory (by reading Avi Rubin and Roger Johnston) that tamper-indicating seals aren’t very secure, but I hadn’t really tried anything myself.

Here’s what is not so obvious: If you want to study how to lift and replace a seal without breaking it, or how to counterfeit a seal, you can’t practice on the actual voting machine (or other device) in the polling place! You need a few dozen samples of the seal, so that you can try different approaches, to see what works and what doesn’t. Then you need to practice these approaches over and over. So step 1 is to get a big bag of seals.

What I’ve discovered, by whipping out a credit card and trying it, is that the seal vendors are happy to sell you 100 seals, or 1000, or however many you need. They cost about 50 cents apiece, or more, depending on the seal. So I bought some seals. In addition, under Court order we got some samples from the State, but that wasn’t really necessary as all those seals are commercially available, as I found by a few minutes of googling.

The next step was to go down to my basement workshop and start experimenting. After about a day of thinking about the seals and trying things out, I cracked them all.

As I wrote in December 2008, all those seals are easily defeated.

  • The tamper-indicating tape can be lifted using a heat gun and a razor blade, then replaced with no indication of tampering.
  • The security screw cap can be removed using a screwdriver, then the
    serial-numbered top can be replaced (undamaged) onto a fresh (unnumbered) base.

  • The wire seal can be defeated using a #4 wood screw.
  • The plastic strap seal can be picked using a jeweler’s screwdriver.

For details and pictures, see “Seal Regime #2” in this paper.

Seals on NJ voting machines, 2004-2008

I have just released a new paper entitled Security seals on voting machines: a case study and here I’ll explain how I came to write it.

Like many computer scientists, I became interested in the technology of vote-counting after the technological failure of hanging chads and butterfly ballots in 2000. In 2004 I visited my local polling place to watch the procedures for closing the polls, and I noticed that ballot cartridges were sealed by plastic strap seals like this one:

plastic strap seal

The pollworkers are supposed to write down the serial numbers on the official precinct report, but (as I later found when Ed Felten obtained dozens of these reports through an open-records request), about 50% of the time they forget to do this:

In 2008 when (as the expert witness in a lawsuit) I examined the hardware and software of New Jersey’s voting machines, I found that there were no security seals present that would impede opening the circuit-board cover to replace the vote-counting software. The vote-cartridge seal looks like it would prevent the cover from being opened, but it doesn’t.

There was a place to put a seal on the circuit-board cover, through the hole labeled “DO NOT REMOVE”, but there was no seal there:

Somebody had removed a seal, probably a voting-machine repairman who had to open the cover to replace the batteries, and nobody bothered to install a new one.

The problem with paperless electronic voting machines is that if a crooked political operative has access to install fraudulent software, that software can switch votes from one candidate to another. So, in my report to the Court during the lawsuit, I wrote,


10.6. For a system of tamper-evident seals to provide effective protection, the seals must be consistently installed, they must be truly tamper-evident, and they must be consistently inspected. With respect to the Sequoia AVC Advantage, this means that all five of the
following would have to be true. But in fact, not a single one of these is true in practice, as I will explain.

  1. The seals would have to be routinely in place at all times when an attacker might wish to access the Z80 Program ROM; but they are not.
  2. The cartridge should not be removable without leaving evidence of tampering with
    the seal; but plastic seals can be quickly defeated, as I will explain.

  3. The panel covering the main circuit board should not be removable without removing the [vote-cartridge] seal; but in fact it is removable without disturbing the seal.
  4. If a seal with a different serial number is substituted, written records would have to reliably catch this substitution; but I have found major gaps in these records in New Jersey.
  5. Identical replacement seals (with duplicate serial numbers) should not exist; but the evidence shows that no serious attempt is made to avoid duplication.

Those five criteria are just common sense about what would be a required in any effective system for protecting something using tamper-indicating seals. What I found was that (1) the seals aren’t always there; (2) even if they were, you can remove the cartridge without visible evidence of tampering with the seal and (3) you can remove the circuit-board cover without even disturbing the plastic-strap seal; (4) even if that hadn’t been true, the seal-inspection records are quite lackadaisical and incomplete; and (5) even if that weren’t true, since the counties tend to re-use the same serial numbers, the attacker could just obtain fresh seals with the same number!

Since the time I wrote that, I’ve learned from the seal experts that there’s a lot more to a seal use protocol than these five observations. I’ll write about that in the near future.

But first, I’ll write about the State of New Jersey’s slapdash response to my first examination of their seals. Stay tuned.