Threat-Model Based Padlock Selection

Threat Model Based Padlock Selection

Today I will cover some padlocks that I use and personally recommend.  Padlock selection should occur based on the threats they are likely to face.  There are two basic threat models I use when selecting padlocks.  The first is low-to-medium security applications.  These locks will be robust enough against forced entry and offer some light protection against picking and other surreptitious defeat.  The other is high security.  The cost of a high security lock is justified in several instances: if surreptitious entry is a legitimate concern.  They are also preferred for unattended containers.  This might be your luggage†, your gym locker, or a shed on a vacation property.

General Padlock Selection Criteria

There are a few criteria that I look for regardless of the threat model.  The first is overall quality and reputation.  All of the manufacturers I recommend here have excellent reputations for producing quality products (save Noke, which is brand new).  Quality usually translates directly to tighter tolerances and higher quality materials.  Since the shackle of a padlock is generally its weak point, I also look for hardened shackles.  The bodies of some of the locks I recommend here are brass or aluminum, all have hardened steel shackles of specially tempered steel or a boron-alloy for cutting resistance.  Finally, I look at the shackle retention mechanism.

There are various techniques for bypassing padlocks that involve defeating the shackle-retention system that consists of a spring-loaded plunger.  These include shimming and rapping.  All of the padlocks I mention in this post, and all of the padlocks that I personally use, DO NOT have a spring-loaded shackle retainer.  Instead, these locks use a system of ball bearings to keep the shackle closed.  The photo below illustrates how the ball-bearing system works.  When the lock is closed the ball bearings are held in place by the brass billet.  When the key turns the cylinder, it turns this billet, allowing the ball bearings to retract into the cutouts on its opposing sides.  The shackle can then be opened.  The image on the left shows the lock in the locked condition; the image on the right shows the lock in the unlocked/open condition.

Threat Model Based Padlock Selection

Low – Medium Security Padlocks

American Lock:  American Lock is famous for filling their cyliders will anti-pick pins.  Top pins are either serrated, or spooled and serrated, and bottom pins are serrated (serrating bottoms pins is extremely uncommon, even on many high-security locks).  The locks are robust and known for being very high quality.  American padlocks are also rekeyable in most cases.  This means your local locksmith can rekey, key alike, or master key them.  They have been used by the US Military in low security applications for decades.  NOTE:  Though American and Master are owned by the same company (Master Lock), I DO NOT recommend any Master-branded lock.

Threat Model Based Padlock Selection
An American 5200 and Master #3. Note the presence of ball bearings in the American. Also not the security pins from the American in the image at right.

My go-to for general use is the American 5200-series.  This mid-sized padlock only has five pins, but is still a tough pick.  It’s also amazingly rugged, and the shackle will just fit in the locking lugs on larger Pelican cases.  For larger/heavier applications the American A700D padlock is hard to beat, and if you need a more conventional padlock with shackle protection, check out the American A5300D padlock.  If you have a door or other item that requires a hasp, check out the American “puck lock”.  This shackle-less padlock is very resistant to forced entry and has a six-pin cylinder.  The photo below shows an unattended newstand in the (proverbial) shadow of the Empire State Building. The use of  2000-series puck lock and a 700-series padlock, both by American, is a testament to their quality.

Threat Model Based Padlock Selection

Abus Titalium Line:  Though I have far less experience with this line of padlocks, I have been around them enough to know they are very good locks, and Abus has a well-deserved reputation for producing excellent locks.  The body of the Titalium series feature an aluminum alloy body that is much much lighter in weight than a comparably sized American.  The lighter weight may be good for situations where weight really matters – like luggage.  The shackle is a very hard steel alloy for cutting and sawing resistance, and the shackles are held in place with ball bearings.  I have used the 80IT/50 version, which has six pins, and the smaller 64TI/30. The 64TI/30 is only a four-pin lock, but it is great for smaller applications, like handgun-sized Pelican cases like the 1170.

Noke Padlock:  I am generally wary of electronic locks.  I have been to numerous lock defeat courses where I have seen them fail, and it is not confidence inspiring.  However, I recently became aware of the Noke “Keyless Bluetooth Smart Padlock” from BosnianBill.  Bill attempted a number of defeats against this lock, all of which were unsuccessful.  After finally resorting to an 18-lb grinder he was able to cut the shackle before disassembling the lock to inspect it’s inner workings.  The lock is unlocked through a Bluetooth transmission from your smartphone, and a single app can manage multiple locks.  I have yet to get my hands on one, but am looking forward to it. If you are in the market for a lock that doesn’t require physical keys you could do much, much worse than this one.

High Security Padlocks

High security padlock selection is easy for me.  There is only one brand of high security lock that I recommend and personally use: it is the Abloy Protec2.  The Abloy design is very novel.  It relies on rotating disks rather than pin tumblers, and is nearly impossible to defeat surreptitiously.  Additionally, because there are no springs in the Protec, it is impervious to extreme cold and other environmental conditions that can be detrimental to lesser locks.  Because there is an element on the key that must be able to move to operate the lock, unauthorized key duplication is also nearly impossible.

This video demonstrates how the Protec2 works, beginning at 0:58.  There is only one online source that a I am aware of that is an authorized vendor of Abloy padlocks: Security Snobs (I have no financial interest in any sales through Security Snobs).  Though there are a number of Abloy padlocks, there are two mainstays for me: the PL 330 and the PL 975.  The PL 330 is your average, mid-sized padlock.  It will fit through the locking tabs on Pelican cases and is not overly heavy.  The PL 975 is Abloy’s puck lock.

†Yes, it is possible to use very good (read: non-TSA) locks on your checked airline luggage.  To do so you must travel with a firearm.  For details see this article I wrote for Lucky Gunner Lounge.

If you enjoyed this article and would like exclusive content, sign up for the Operational-Security Newsletter.

Leave a Reply