Key Blanks and Restricted Profiles 2026: Open, Restricted and Patented Keyways, and What Key Control Actually Buys

Two locks can take the same key bitting and still not share a key, because the key has to get into the plug before the cuts matter. The shape that decides this is the keyway, and the piece of metal cut to match it is the blank.

This is the part of a locking specification that gets decided last and is the hardest to change afterwards, because changing it means changing every cylinder in the building.

BLANK, PROFILE, BITTING

Three words that are often used loosely and mean distinctly different things.

The profile, or keyway, is the cross-section of the slot in the cylinder plug — the pattern of grooves and ribs that the key must match to enter at all.

The blank is an uncut key with that cross-section. It fits the keyway and turns nothing, because it has no cuts.

The bitting is the pattern of cuts made into the blank, and it is what actually lifts the pins to the shear line. Two keys with the same bitting and different profiles are not the same key. Two keys with the same profile and different bittings enter the same lock and one of them turns.

Key control — the ability to say who can get a copy of a key — operates almost entirely at the profile level, not the bitting level. Anyone with a code machine can cut a bitting. The question is whether they can get the blank.

OPEN KEYWAYS

An open or unrestricted profile is one whose blanks are freely sold. Any key cutter has them, a hardware shop has them, and a copy takes two minutes and costs almost nothing.

This is the correct specification for a great many doors, and saying so is not a criticism. A stationery cupboard, an internal office, a domestic interior door — these do not need key control, and paying for it buys inconvenience rather than security.

What an open keyway cannot do is tell you how many keys exist. Once a key has left the building it can be copied, and there is no record and no way to find out. Any assessment of an existing building with open keyways should assume the key population is unknown.

RESTRICTED KEYWAYS

A restricted profile is one whose blanks are not sold openly. The manufacturer controls distribution, and blanks reach only authorised dealers, who are supposed to cut only against an authorisation.

This is a commercial and contractual control, not a physical one. The protection is exactly as strong as the distribution agreement and the dealer's diligence, and it has no force against someone who obtains a blank by other means.

It is nevertheless useful and often proportionate. It converts casual copying from a two-minute errand into something that requires intent and leaves a trail, and for most commercial buildings that is the actual threat model.

PATENTED KEYWAYS

A patented profile adds a legal monopoly on the blank itself. While the patent is in force, nobody else may lawfully manufacture that blank, which means unauthorised copying requires either an illegal manufacturer or a physical original to duplicate.

This is the strongest form of key control, and it comes with a date attached. A patent has a term. When it expires, the blank may lawfully be manufactured by anyone, and third-party blanks generally do appear.

That is the sentence most worth carrying away from this page. A building specified with a patented system ten years ago may be operating today on a profile whose patent has lapsed, with the facilities team still describing it as a patented system because that is what the handover documents say. The key control that was purchased has quietly expired, and nothing in the building changed to announce it.

If you are assessing an existing system, find out the patent's status rather than its original claim. If you are specifying a new one, ask how long the patent has left — a system with two years remaining is a different purchase from one with fifteen.

WHAT KEY CONTROL DOES NOT STOP

It is worth being exact here, because key control is frequently sold as though it were a security grade.

It does not resist attack on the cylinder. Picking, bumping, drilling and snapping are properties of the cylinder's mechanism and construction, not of its keyway, and a patented profile on a weak cylinder is a well-controlled key for a lock that can be defeated without one.

It does not stop a key being lent, lost or kept by a departing employee. That is a procedural problem and needs a procedural answer — a register, a return policy, and a plan for rekeying.

It does not protect the rest of the opening. As covered on our strike plate page, a deadbolt throwing into an unlined jamb hole with two short screws is where most forced entries actually give way, whatever cylinder is above it.

THE KEY REGISTER, AND WHY IT IS THE REAL DELIVERABLE

A master key system's lasting value is not the cylinders; it is the documentation. A key register records which keys exist, which bittings they carry, who holds them and which doors they open.

Without it, expanding a system means reverse-engineering it, and a system that has been extended twice without a register usually cannot be extended a third time without starting over. That is a cost measured in cylinders for the whole building.

Ask for the register as a deliverable at the point of order, in a format you can read without the supplier's software. A key register that exists only inside one company's system is a register you do not fully own.

WHAT HAS TO BE DECIDED BEFORE CUTTING

The profile, and its status — open, restricted or patented, with the patent expiry if patented.

The hierarchy. Which keys open which doors, and how many levels the system needs. Our master key systems page covers why adding a level after the fact is expensive.

The expansion allowance. A system cut to exactly today's building has no room, and buildings change. This has to be designed in at the start; it cannot be added later.

Who may authorise a cut, in writing. This is the control that actually operates day to day, and it is the one most often left undefined until the first time somebody needs a spare urgently.

The cylinder length and split for every door, because a master key system is a set of cylinders and every one of them has to physically fit its door. Our euro cylinder pages cover how to measure that.

WHAT WE CONFIRM PER ORDER

Keyway availability is a per-order question rather than a catalogue property, because it depends on the cylinder range, the quantity and the market. We confirm the profile, its status and what is committed on key control before an order is placed, in writing.

We do not publish a general claim about key control on product pages, because a claim like that is only meaningful attached to a specific profile, a specific term and a specific distribution arrangement. A supplier who advertises key control without those three has advertised a word.