any master pins at all, because the master key and the change key will have the exact same bitting, just on different blanks. There are numerous examples where more than one key section will fit into a keyway. Oſten, they are designed specifi- cally for that purpose, and they’re known as multiplex keyways. For example, you might have a master keyed building with Yale GA keyway and another building with Yale GB keyway, with identical key bittings in both systems. The GA keys won’t fit the GB locks and the GB keys won’t fit the GA locks, but a Yale GV key will fit them both. If you copy either the GA or GB master onto a GV blank, voila: You have the grand master key. Our community center example is a little different, because the Primus CP was designed to fit into the C keyway to provide key control for existing sys- tems, not for sectional master keying. But it works for this situation. Even bet- ter, the fact that Primus XP keys are pat- ented and restricted helps to mitigate two problems. First, a danger with sectional master keying is that a holder of a low- level key might get their key copied onto a higher-level blank, which effectively elevates the key. Primus XP keys are pat- ented and restricted, which makes such an elevation much less likely. Second, using a restricted key makes the system harder to hack. Hacking is an unavoid- able vulnerability of split-pin master key- ing. Essentially, every lock that operates with the master key contains the infor- mation about what cuts are on the master key. It’s even possible to decode the lock without disassembling it if you have a code machine and a supply of key blanks. Restricted key blanks are harder to get, which makes hacking less likely. One downside of this plan for the Sand- ford Community Center is that when a change key is lost or stolen, rekeying won’t be as simple as choosing the next 42 KEYNOTES JANUARY 2022 change key bitting from a progression list. In this case, when we choose a new change key bitting, the master key bitting must change with it. That means cutting all new keys. Nothing is perfect. Remem- ber, master keying is all about weighing the advantages and disadvantages. Example #3: Apartment Building. The owners of Oak Winds Apartments have called us to schedule a rekey of a dozen apartments (in preparation for the next col- lege term) and because their gate lock keeps jamming. Naturally, our first reaction is to be cautious and curious, because residences usually shouldn’t be master keyed. The advantages of master keying in residences are usually outweighed by the disadvantages. First, the locks tend to be residential grade five-pin, which aren’t terribly secure to begin with. Then we decrease the physical security even more by putting in master pins. Even worse is the possibility of hacking the system. Tenants have access to their own change keys and their own locks, which contain all the information about the bitting of the master key. And the stakes are higher with residences than with businesses. A lawsuit involving stolen office equipment could be in the thousands. A lawsuit in- volving the death of a human being could be in the millions. Considering all this, it makes us wonder why they decided to master key the building at all. Despite the downsides, the owners of this 30-unit building are concerned that there might be an emergency, such as a leaking water pipe, that would require ac- cess to any apartment at any time. They are convinced that a master key system is the way to prepare for such emergencies. We ask to see the master key system records to find out just how bad the situation is. All they have are invoices showing dollar amounts charged by various lock- smiths over the years. They don’t have a bitting list. We ask to see what keys they have. They produce a master key and a handful of change keys. The master is a Kwikset key stamped “MASTER” on one side and “DO NOT DUPLICATE” on the other. The change keys appear to be fac- tory original keys. This is looking worse by the minute. Nine times out of 10, a master key system with factory original keys is a “shoebox” system. We use a key gauge to decode the keys, make a list and mark the constants with a yellow high- lighter. Here are the results: master 56656 change 43251 change 42412 change 36411 change 15233 change 23646 The fact that the constants move around is not a problem. That’s a normal feature of a rotating constant system. The real problem is that some of the keys have no constants, some have one and one has two constants. Normally, all the change keys in a system should have the same number of constants. We can conclude this is indeed a shoebox system. That ex- plains the fluctuating constants. It also explains why they have no bitting list. Shoeboxing doesn’t need any paperwork at all; that’s one of the reasons amateur locksmiths like it. Unfortunately, shoeboxing uses more master pins than necessary, and it relies on luck to avoid key interchange. That’s why it’s expressly forbidden by ANSI/BHMA A156.28. With a system of 30 keys, the chances are very high that they already have key interchange; they just haven’t noticed it yet. We really should rekey this entire building. If we are working with a blank slate, what kind of system could we create? WWW.ALOA.ORG
