Rekeying: Changing the Key Without Changing the Lock

What Rekeying Is

The Lock Industry Standards and Training (LIST) Council's Professional Locksmith Dictionary defines "rekey" as "to change the existing combination of a cylinder or lock." The combination is the set of cut depths, the bitting, that a key must have to operate that cylinder.

In a pin tumbler cylinder, the bottom pins touch the key and the top pins sit above them under spring pressure. Schlage's key systems glossary describes the bottom pin as the tumbler "that comes in direct contact with a key." The plug turns only when the split between each pair of pins lines up with the shear line. Because the bottom pin lengths are matched to the key's bitting, changing them changes which key works. That change is the whole of a rekey: the combination moves, and the hardware stays.

Rekey, Replace, or Swap the Core

Three different jobs can solve a key problem:

• Rekeying changes the combination inside the existing cylinder.
• Replacing removes the lock or cylinder and installs new hardware. That is the route when the goal is something rekeying cannot change, such as a different security grade, a different lock type, or a different function, because rekeying alters only the combination.
• Swapping an interchangeable core replaces just the keyed core. LIST defines an interchangeable core as "a key removable core which can be used in all or most of the core manufacturer's product line," removable with no tools other than the control key. Schlage's guide says interchangeable cores "allow cylinder rekey or replacement without disassembly of the lock," while a conventional cylinder "commonly requires some disassembly of the lock for removal and replacement."

Schlage's guide calls interchangeable cores ideal for "larger campuses or facilities with high rates of occupant turnover," and conventional cylinders best suited to places with "tight key control and little need to periodically rekey." It uses the terms SFIC (small format interchangeable core) and FSIC (full size interchangeable core). See interchangeable cores.

When Rekeying Is Done

Rekeying answers one question: who holds working keys. Documented examples include:

• Moving in or tenant turnover. Kwikset lists "Recently moved, tenant turnover" and "Loaned or unreturned keys" among its reasons to rekey, adding that "the person who has your key today may not be the same person you want to have your key tomorrow."
• Lost keys. Kwikset's list also includes a child who "has lost their key... again."
• Employee turnover. Locksmith Ledger's article on small format interchangeable cores notes that businesses with frequent staff changes, such as fast food chains, often use interchangeable cores so they can change the core "at any hour as needed."
• Consolidating keys. Kwikset notes that owners can rekey several locks to one key so that all entry doors are keyed alike.

Rekeying changes only the combination. It does not repair a worn latch, a weak strike, or a damaged door.

Rekeying Within a Master Key System

In a master key system, one cylinder may answer to several keys. LIST defines a master key system as "any keying arrangement which has two or more levels of keying." Schlage's glossary explains that a master pin is "used between the bottom and top pins to create additional shear lines," which is how a single cylinder can open to both its own change key and a master key.

Because of that, a cylinder in a master system cannot be rekeyed on its own terms. The new combination has to fit the system so that the right master keys still work and no unintended keys do. The system's records exist for this purpose. LIST defines a bitting list as "a listing of all the key combinations used within a system" and a keying schedule as "a detailed specification of the keying system listing how all cylinders are to be keyed." Rekeying inside a system follows those records. See master keying and construction keying.

Consumer Self-Rekeying Products

Some residential locks are designed so the owner can rekey them without a locksmith. The best-known example is Kwikset's SmartKey Security. Everything in this section is the manufacturer's own description, and Pin and Ward has not tested it:

• Kwikset describes SmartKey as "re-key technology, which allows you to re-key your locks yourself in seconds," and calls it "the first DIY re-keying product on the market."
• Kwikset says SmartKey "is a patented cylinder design only available on Kwikset products" and cannot rekey other brands.
• Kwikset says the process "requires the current working key and the SmartKey Security® tool," so "only someone with both of those items can rekey your lock." If the working key is lost or stolen, Kwikset recommends contacting a builder, locksmith, or its support team.

This article does not describe the rekeying procedure. Kwikset publishes its own instructions for owners.

Key Control After Rekeying

A rekey restores control over who holds working keys only for as long as new keys stay controlled. LIST defines key control as "any method or procedure which limits unauthorized acquisition of a key and/or controls distribution of authorized keys," and as "a systematic organization of keys and key records."

Schlage's guide separates "administrative security," which "is about key control" and the "barriers you put in place to prevent unwanted duplication," from physical security, which concerns a cylinder's resistance to "picking, bumping or drilling." Rekeying addresses the first, and only at the moment it is done. If the new keys are on an open keyway, they can be copied as easily as the old ones. Patented and restricted keyways limit who can obtain blanks and cut duplicates.

Related Topics

• Pin tumbler locks
• Key bitting
• Master keying
• Construction keying
• Interchangeable cores
• Key control
• Restricted keyways
• Kwikset

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