Threat Model-Based Deadbolt Selection

Threat Model Based Deadbolt Selection

Several weeks I ago I wrote a post about Mechnical Lock Threat Models, detailing categories of locks, and the users who should have them. In this post I am looking specifically at deadbolt selection, and offering some recommendations based on my mechanical lock threat models.

Grade 0 Deadbolt Selection

As I mentioned in the mechanical lock threat modeling post, users of Grade 0 locks have legitimate concerns about surreptitious entry, as well as more pedestrian concerns about forced entry. I only recommend one lock in this category: the Abloy Protec2. The Protec2 is one of the most mechanically secure locks in the world. Instead of pins that are raised up and down, the Protec system has 11 rotating discs that must be rotated to the correct position in unison to allow a sidebar to retract. The Protec mechanism is nearly impossible to pick, and (truly) impossible to bump.

My favorite source for these locks is Security Snobs.  Security Snobs is an online retailer of very high-end mechanical locks from Abloy and EVVA and a few others.  Please note I have no interest, financial or otherwise, in Security Snobs. I prefer the Abloy Protec2 “single-cylinder with lockable thumbturn deadbolt“.  The entire lock is constructed of hardened steel. It also is available with an “expanding bolt”, which forces two ball-bearings into the steel strike box (shown in the center photo below). This makes it nearly impossible to separate the bolt from the strike box. All new Abloy Protec and Protec2 locks include a strike box.

Threat Model Based Deadbolt Selection - AbloyThe “locking thumbturn” portion of the lock allows you to choose from two different “modes” in which the lock can be operated. In standard mode it is a single cylinder deadbolt: a key is required to lock or unlock from the exterior, while the thumbturn can be used to lock or unlock it from the interior. The thumbturn also has a keyway, however. Locking the thumbturn prevents it from being operated without a key, effectively making the lock a double-cylinder deadbolt.  This is useful if you don’t want your lock to be a double-cylinder while your residence is occupied, but would like the option when you are away for the day or on vacation.  The photo above (right) shows the interior thumbturn with keyhole.  A red tab protrudes from the top of the lock body when the thumbturn is locked.

The Protec2 also features a moveable element (a very small ball-bearing) on the key. If this element is not present or cannot move, the lock will not open. Creating a key blank would require incredibly sophisticated machinery and skill.  This means you can issue out keys with complete confidence they are not being duplicated. You can also rest assured that a key cannot be generated by impressioning. The Protec2 is also available with a dealer-exclusive keyway. This means that Security Snobs is the only dealer in the world with key blanks that will fit into your locks. If you give a key to your dog walker, baby sitter, or house cleaner you have complete confidence that it will not be duplicated.  If you choose the locking thumbturn model, you can also order an “emergency” key from Security Snobs. This key will operate the interior cylinder ONLY, meaning it can only be used to unlock your house from inside. You can leave a key by the door to use during emergencies, without worrying that it will be stolen and later used to enter your house.

Threat Model Based Deadbolt Selection - Abloy KeyThere are many other high security options out there, and I encourage you to do your own research and use what you feel comfortable with. I like the Abloy. I would also feel extremely comfortable with the ASSA V-10 or Schlage Primus, or the Mul-T-Lock MT5+.  Many of these locks can be difficult to source online, and may require locating an authorized dealer in  your area.

More Affordable Option: If you already have a decent deadbolt with a standard pin tumbler mechanism, you may be able to replace the cylinder with a high-security option.  Security Snobs offers Abloy retrofit cylinders for a much more reasonable price than a full deadbolt.  Keep in mind that these will make covert entry techniques against your lock more difficult, but will not greatly increase forced-entry resistance.

Grade 1 & 2 Deadbolt Selection

I lump these categories together because the locks are functionally the same. The only major difference between these categories is in the ANSI/BHMA grading (Grade 2 or Grade 1) and the forced entry resistance conveyed in the respective grade. Later this week I will post some techniques you can use to increase the security of Grade 1 or 2 locks to produce what I call “Grade 1 – Enhanced” hardware. These techniques can be applied to new or existing locks to increase their level of security. Due to the neglible cost difference between residential Grade 1 and 2 hardware, I have only provided links to Grade 1 locks.

For users in this category who desire a  I recommend a simple Grade I Schlage deadbolt. The Schlage B-Series deadbolts are residential hardware that meet the Grade 1 standard.  Specific locks: Schlage B60 (single cylinder) and Schlage B62 (double cylinder). I also (reservedly) recommend the Kwikset SmartKey deadbolts for individuals in this threat model.  While not impervious to lockpicking, decoding, or other defeats, this lock is ANSI/BHMA certified Grade 1 for forced entry resistance.  Additionally, the SmartKey system allows you to quickly and easily change your key in the event your lose control of one.  Even though the SmartKey can be picked, this is not a realistic threat model for most. Also, not to rain on anyone’s parade, but the pin tumbler locks mentioned above aren’t pick-proof, either.  Specific locks: Kwikset 980 (single cylinder) and Kwikset 985 (double cylinder).

Threat Model Based Deadbolt Selection

Grade 3 Deadbolt Selection

As I pointed out in the Mechanical Lock Threat Models post, I don’t recommend Grade 3 locks to anyone. Though these locks are inexpensive, they are also invariably cheaply and poorly manufactured.


Quality isn’t cheap. I don’t mean to suggest that everyone needs to pay in excess of $400 per lock for an Abloy with all the bells and whistles.  I do recommend that you buy the best lock you can afford. Take the time ensure that it is installed and adjusted correctly.  Lock the door when you leave. Get some motion lights. If you can’t afford an alarm system, get some alarm stickers.  Make yourself the hardest target you can. In an upcoming post I am going to talk about some steps you can take to enhance the security of Grade 1 hardware or the locks you already have, so stay tuned!

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