High-Security Locks

High security is three separate properties wearing one label. A cylinder can be nearly impossible to get a copied key for and still be drilled out quickly. It can shrug off a drill and be picked open. Deciding which of the three you are actually buying is the whole decision, and it is the question that almost never gets asked at the counter.

The second thing to hold on to is that the cylinder sits inside a lock, inside a door, inside a frame. Fitting a cylinder that resists every attack you can name to a door whose strike is held by two short screws into soft timber does not remove the weak point. It relocates it somewhere less obvious and leaves you feeling better about a door that is no harder to get through.

The three things the phrase can mean

• Key control. Restricted or patented blanks are not sold across a counter, so a copy has to come through the system and be authorised by the registered holder. This is the property most people actually want when they say high security, and the one they least often ask for by name.
• Manipulation resistance. Sidebars, interlocking or telescoping pin stacks, spool drivers and rotating elements make a cylinder far harder to pick or bump. It is what the specification sheets talk about most, and what the average front door is least likely to face.
• Physical attack resistance. Hardened steel inserts against drilling, reinforced housings against twisting, and cylinders with a sacrificial section engineered to break along a defined line so the working part stays in the door when the exposed part is snapped off.
• The grade of the lock body itself. The ANSI and BHMA scale grades a lock by cycles, load and impact rather than by how clever the cylinder inside it is. Commercial-grade bodies survive daily abuse that lighter residential hardware does not.
• Everything around it. Frame, strike, screws, hinges, glazing and the door slab. A door is a chain, and the cylinder is only ever one link in it.

Worth deciding first

• Which of the three properties matters most for this particular door.
• Whether keys have already gone missing, or been copied by somebody without asking you.
• How many doors would go on the system, and whether they should all answer to one key.
• Whether this is a home, a small business, or a shared entrance with a lot of holders.
• Whether you are willing to be the named holder on record, because a restricted system requires somebody to be.

Medeco and Mul-T-Lock

Two names come up most often when “high security” gets specific:

• Medeco cylinders use an angled, rotating pin design on top of the usual height cuts, so a standard key blank cannot be duplicated at a hardware-store machine — copies require an authorized dealer and, on patented profiles, the owner's signature on file.
• Mul-T-Lock uses a telescoping pin-within-a-pin design with a similar dealer-authorization model for restricted keyways, and is common on both cylinders and padlocks in the same product family.

Both are installed and serviced as part of this business's high-security and restricted-key work; which one fits a given door usually comes down to the keyway restriction level wanted and what is already on the property.

Common questions

Related locksmith services