Security Review: “Smart Guns”

By Trip Volpe at 11:59 pm on March 16, 2008 | 18 Comments


This is a security review of “Smart Guns,” a general class of locking/use prevention mechanisms for firearms that rely on biometrics or other authentication indicators (such as “smart” chips embedded in the gun and in rings or other tokens worn by the intended user) to identify a person who is authorized to use the firearm, while preventing unauthorized persons from discharging the weapon. The Wikipedia article has some further broad overview information regarding the subject.


  • Accessibility. Ideally, one security goal is for the firearm to be capable of being used in short order by the authorized user.
  • Personal safety. The other security goal is that an unauthorized individual should not be able to use the gun to injure or kill the owner or any other person.


  • The most obvious potential adversary is a criminal intent on using someone else’s gun to do harm; e.g., a criminal struggling with a police officer or a burglar breaking into someone’s house.
  • Another “adversary” could be the small children of the owner of such a firearm; if a child somehow gains access to the firearm, the locking mechanism should be capable of preventing them from discharging the weapon and possibly killing or injuring themselves or others.

Possible Weaknesses

  • If the locking system requires a battery to operate, one major problem that could compromise one of the security assets is a dead battery. If the battery is dead and the gun cannot be unlocked, it is useless to its owner, whether that be a police officer in the line of duty, or a civilian trying to defend himself from an attacker.
  • If the system relies on biometrics to identify the owner (such as grip style, pulse, or other such indicators), a stressful situation (such as a shootout) might substantially change those indicators in the user, resulting in the owner being unable to use the firearm.
  • Further, if the owner of a firearm is killed or injured in a gunfight, a partner, family member, or other ally will be unable to use their weapon against the attackers.

Possible Defenses

  • To guard against the “dead battery” problem, one option is to design the lock so that the default (unpowered)  state is unlocked. This prevents the accessibility of the firearm from being compromised, but it also poses a major problem itself: when the battery dies, it is no longer protected against unauthorized use, and it might be possible for an adversary to damage or disable the battery, thus unlocking the firearm. A better solution might be to devise a system that does not require internal power, although this poses a significant technological challenge.
  • Situations where an ally might need to use another’s gun to continue a fight arise more often in law enforcement; agencies might be able to employ a system where all officers could be issued tokens (e.g., rings) that would grant access to use all of the department’s issued firearms.


As with anything involving firearms, the risks are quite substantial:

  • If the battery dies or another circumstance renders the gun unusable, the consequences could be quite dire, depending on the situation: if the user is practicing at the range, the result would be an annoying delay while the battery was replaced; if, on the other hand, the user is attempting to defend his or her life against an attacker, the result could easily be serious injury or death.
  • On the other side of the issue, if an unauthorized user gains access to a firearm that is not protected (e.g., the firearm was unprotected, or the battery has died and the mechanism defaults to unlocked), they could use it to kill or seriously injure the intended user or others, or in the case of a small child, themselves.


While “Smart Gun” technology proposes to address a good security goal (namely, preventing a bad guy from turning someone’s gun against them), reliability is a major issue. In most of the eventualities when such a locking system becomes important, absolute reliability and speed of access are also critically important for the user. For this reason, many people do not consider the technology to be worthwhile at the present time. Ultimately, a better solution for most people is to employ other methods of keeping the firearm out of undesirable hands in the first place, rather than trying to defend against an adversary who already has physical access.

Filed under: Availability,Physical Security,Policy,Security Reviews18 Comments »


  • 1
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    Comment by Brian S

    March 17, 2008 @ 10:29 pm

    I really like this idea. It solves one of the major problems of guns – accidental shootings. It does seem to add significant overhead to the use and care of a firearm, though I think the overhead is worth the risk. Much of that overhead is due to the charging and state of the battery. I imagine the system would be fairly low power, but that depends on the locking mechanism. Considering the cost to implement a system like this, and train people in its proper use, and replace/modify all existing firearms with new, locked ones, is just too great. I have to agree with Trip’s conclusion that limiting access to the firearm itself has a higher chance of adoption, due to its low cost.

  • 2
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    Comment by Trip Volpe

    March 18, 2008 @ 2:31 pm

    Well, it’s not always lower cost – a good gun safe can be pretty expensive. 🙂

  • 3
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    Comment by croikle

    March 19, 2008 @ 10:11 pm

    If this system became widely adopted, and you managed to crack it, you could shoot someone with a stolen gun and send someone else to jail. (assuming you could convince people the system was foolproof)

  • 4
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    Comment by Pranav Swaroop

    March 21, 2008 @ 1:52 am

    In response to the “significant technological challenge” under “Possible Defenses”, may I suggest a simple four digit mechanical combination lock? 🙂

    Once the gun is in use, death/disability of the actual owner does not preclude usage of weapon. Downside- the weapon can now be captured by the enemy, but atleast weapons will be protected from unauthorized use while in storage.

    In India, for example, there are Maoist attacks on police stations where the armouries are raided and weapons captured. A simple low-cost solution such as this one could be useful in such situations. Something like this could also help stop school shootings.

  • 5
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    Comment by Spyder

    March 21, 2008 @ 4:30 am

    Universal codes:
    Also remember that those “rings” are likely giving off a RFID signal or come in contact with the grip in a specific manner. No matter how faint the signal, you can easily acquire it.
    Whether you obtain it through a pay-off to a shady cop, have a prostitute scan it during/after sex, or from the body of the officer (unconscious or dead). Stealing the (possible) device just warns that they need to change the code.
    Would possibly be some time before the agency discovered their code had been breached and needs to be changed.

    And the time spent on the investigation? Would likely end with no one sure of how the criminal obtained the code/device.

    Agencies probably need to take into account that they may have 10-20% bypassing their security and deem it acceptable against the 100%.

  • 6
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    Comment by Spyder

    March 21, 2008 @ 4:42 am

    In the end, no means of security is 100%. And we wage the constant battle with the average person between security and simplicity of use (how many people hate taking their shoes off at the airport).

  • 7
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    Comment by Howard Smith

    March 21, 2008 @ 5:55 am

    > (how many people hate taking their shoes off at the airport).

    or wearing pink stars to denote they are the wrong religion


    (That was meant to be an ironic comment on the fact that several battles are being waged, including also the one between the people and the power-hungry despots who rise to power in all governmental systems.)

  • 8
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    Comment by Kent's Imperative

    March 21, 2008 @ 6:23 am

    You may wish to look at the older magnetic firearms locking systems, which required that the user wear a ring in order to de-active a safety mechanism. It was rare but occasionally encountered in the 70’s and 80’s for revolvers, and briefly promoted as a potential for a home defense “nightstand gun” for those with children.

    Unfortunately, the key attribute of any firearm must be absolute reliability. Engineering approaches to most “new” weapons do not consider the real nature of this need – and the requirement that the operators which rely upon these weapons trust the weapon absolutely in all circumstances. This is a reason the concept never caught on, and it has nothing to do with cost or a lack of appreciation of the potential upside benefits.

    Interesting discussion, however.

  • 9
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    Comment by David Rees

    March 21, 2008 @ 7:23 am

    The “ring” based locks have been around a long time – they are made for revolvers and are magnetic/mechanical so there are no batteries but the rings are also not unique so the security is mostly a product of obscurity.

    Also, the 3 or 4 digit combination locks are also currently available for certain firearms. The problem with a combination lock is that they key is intangible and easily “copied” and you never truly know who has a key.

    There are over 200,000,000 firearms in the United States so any kind of technology introduced now will only be useful for securing specific guns as retrofitting that many guns is completely impossible.

    My main issue with biometrics and other gimmicks on firearms is they tempt people to rely on them which is extremely dangerous. When people handle a gun, they should know what they are doing and practice safe handling – having these devices may tempt people to rely on the device instead of safe handling practices.

    Accidental gun deaths are always a problem, but in a nation of 300,000,000 people and 200,000,000 guns, annual accidental guns deaths have been steadily declining and are somewhere around the 800 per year mark. That is a little over one person per month per state.

  • 10
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    Comment by nordsieck

    March 21, 2008 @ 2:44 pm

    The only problem that an internal lock on a gun solves is the home-defense gun problem. The issues is that the authentication scheme cannot be made fast enough and easy enough to use for real people in real situations.

    To illustrate, one of the common rules of thumb in security circles is the 21 foot rule. Basically, someone with a holstered firearm has just enough time to draw and fire a single shot at someone making an unexpected attack (charge) from 21 feet away.

    Additionally people tend to lose higher order brain functionality when placed unexpectedly in high stress situations. One of the reasons that double action handguns have become popular is that many people believe they would not successfully remember to disengage a manual safety in a high stress environment.

    Given these extreme usability requirements that firearms present, biometric locks on firearms should face stiff resistance from the people actually use said tools, especially in a security context.

    Finally, biometric id verification may have adverse effects. There have been stories about high end car owners who have lost fingers in the process of robberies so that the criminals could drive their cars away.

    All in all, it does not seem, at this time, that biometric locks on firearms offer better security or higher usability than frame-integrated key locks.

  • 11
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    Comment by Dan Houser, CISSP-ISSAP

    March 24, 2008 @ 5:57 am

    There are two fundamental flaws with a Smart Gun:
    Failure modes – There are thousands of failure modes possible, and all of them can lead to fatalities. What if I need to shoot left handed, because the bad guy winged my right hand? I’m suddenly unarmed in a dire situation. Same issue if the first fight injures my hand, then escalates to the need for deadly force. The liability concerns make this unable to be implemented, IMHO.

    Second big problem is that this is a billion$$ solution, if widely deployed, to an exceptionally rare problem. 99.999% of shootings are made with the shooter being the owner, and a handful where an innocent is holding the gun. I think more would die per year from Smart Gun failures than deaths from the mode it’s design to protect against, where the shooter isn’t the owner.

    As a firearm owner with children, I lock them up, problem solved. A Smart Gun would risk my family. No thanks.

    -Concerned Gun Owner & InfoSec lecturer

  • 12
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    Comment by askme233

    March 27, 2008 @ 8:55 pm

    Linked over from Bruce Scheier’s blog on Security mindset.

    With my mindset, I can’t wait to have them roll this out with RFID lock and a token for the authenticated user. Since these would presumeably be sold to homeowners and law enforcement types anxious to maintain control of their firearms, it would make my day – as a criminal.

    As a criminal I know I would simply need to google to find out how to make a crude RF jammer and I would instantly be able to disarm all cops/homeowners anywhere around me. talk about power.

    Think about how the system can work, but be perverted (hacking), not how it can fail(engineering).

    great blog btw.

  • 13
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    Comment by Guy B. Meredith

    May 3, 2008 @ 7:47 pm

    All smart mechanism using some sort of biometrics or other electronic recognition can be circumvented.

    At some point the electronics are actuating a mechanical device to arm the firearm. This device can be actuated by wiring around the ‘brains’ and directly to the actuator. Alternatively, the actuator can be mechanically jimmied.

    These devices may prevent grabs, but are useless if the criminal or inquisitive child has more than a few minutes to play with the firearm.

  • 14
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    Comment by Dick Baker

    July 7, 2008 @ 2:44 pm

    While the goal of smart gun technology is laudable, the disadvantages outweigh the advantages when one is confronting a criminal. Granted, the odds of an armed citizen confronting a criminal are low, but the percentages are still high enough to cause concern over a gun malfunctioning at the very time it is needed.

    I would have no problem with manufacturers offering such devices as options, much as carmakers offered seat belts as options in the 1960’s. Laws mandating a one-size-fits-all technology, though, put those gun owners who believe in the KISS principle at a disadvantage.

    I keep my defense guns secure from children by storing them in a locked safe. My primary gun is concealed on my person at all times.

    No laws or technology can compensate for a lack of common sense.

  • 15
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    Comment by Dick Baker

    July 29, 2008 @ 9:34 pm

    Aside from the obvious points made about criminals and children being able to circumvent whatever smart gun technology that might be employed, I always wonder why police departments are exempt from legislation requiring smart guns.

    If the police aren’t comfortable defending themselves with smart gun technology, why should we be?

  • 16
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    Comment by Nick

    August 4, 2008 @ 5:55 am

    Another likely workaround is that now people won’t just steal your gun – they’ll also cut off your fingers to operate it.

  • 17
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    Comment by Escorts in Leeds

    September 24, 2008 @ 6:48 am

    Hehe, you guys need to chill out, next time you’re in the Uk, look me up:)

  • 18
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    Comment by Blonde Chat

    November 24, 2008 @ 9:03 pm

    It’s important to make sure the right people have firearms. We don’t want a situation where irresponsible people have guns.

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