Thoughts On Master Keying

With the introduction of electronic locks many years ago, some locksmiths predicted that by this time all metal keys would be extinct. Nothing could be further from the truth.


Specifically in the automotive industry we have seen continuing progress in the reduction and elimination of mechanical keyed cylinders. Fewer and fewer cars each year have keyed cylinders in the trunk, doors or glove box. Even the keyed ignition switch is disappearing. In the commercial and...


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First, decode the master key information and write it down. Then start decoding existing keys in the system, writing down the information. You should soon see some mathematical patterns develop. If the MK and all of the keys in the system have a 5 in the first position, that may be a clue that it was used as a constant throughout the system. If the MK has a different cut value, it may indicate it is part of a rotating constant or the system was progressed to handle floors, departments or areas that group keys in sets. Example: All keys on the third floor have common characteristics or all keys in the marketing department are from the same page or group.

This sort of detective work will provide valuable information that can help you determine the feasibility of expanding or continuing with this system. Careful examination of known cut combinations will reveal which chambers were progressed and in which order.

Incidental Master Keys

Without some clues, you are keying blindly and a new individual office key you generate may have been previously issued as a sub-master or incidental master.

In a properly written system if you pin your lock to the top master key and the lowest individual key, any incidental master keys will work automatically. An incidental master is a generic term for shear lines created by the mathematics of the system.

The mathematical progression will cause each page of a MK system to mirror the other pages with one chamber being different. A fully progressed system with no constants will produce 64 pages of 64 cuts per page, a total of 4096 cuts. Remembering the prime number of 4, each page will have 4 columns with each column containing 4 groups of 4 cuts each.

In addition to the top master key or grand master, each page will contain a page master that fits all 64 cuts on that page, a column master that will fit a vertical column of 16 cuts, a horizontal master that will fit 16 cuts grouped across the page and a group master for each group of four cuts in sequence. Again that prime number of 4 surfaces.

You can’t eliminate these mathematical shear lines that allow these sub-masters to operate. You need to be aware of them and use them to your advantage. Like spaghetti sauce, it’s in there whether you want it or not.

These groupings allow you to issue keys for areas that will provide a sub-master to fit only the locks in that group of 4, 16 or 64. If you need 9 individual door keys and a sub-master, choose a group of 16 and use the built-in mathematical values. Utilize these to create floor masters, department masters, etc.

Conclusions

A properly written and executed system will allow you to assign small or large groups of cuts to your project. Simple keying actions will result in a flexible MK system offering the maximum amount of security to your customer.

Remember that random keying to various cuts is dangerous and destroys any sense of a controlled loss of security. Control the loss with a well thought out system to meet your customer’s needs.

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