Deriving a Master Key

How to derive a master key by probing a single cylinder.

[Mazer]

You explain these potentially confusing concepts so quickly and thoroughly. Brevity is the soul of wit. You have my thanks.

[CaptainCrichton]

Amazing! Simultaneously interesting, humorous, and informative.

[dantescanline]

Awesome series here! Like other commenters have said, you explain very clearly and best of all, quickly. Thanks so much.

[y.k.C.]

Thanks a lot for the clarity in explaining the Master Key

[NetRolllerD]

I always think of it like this: Make the keys with one position blanked, file them down one-by-one, and note any depth that opens. Then compare the found depths to your key:
-If a position has just one working depth, use that depth.
-If a position has two working depth, one of them is on your original key - use the other one.
-More than two working depths indicate a more complex (multi-level) master key setup.

The resulting key is the master key. No need to try 32 keys.

Note: Only works if you have a legitimate user key - a decoded key will likely a mixture of the user and master bittings, so its "inverse" will also contain user bitting pieces, and will not give the master key.

[caitsith]

In having a look at determining the 32 blanks,  you could actually work with 10 blanks, taking advantage of the fact that once you go from the upper cut to the lower,  you can't go in reverse, but you could go onto the lower cut the next position over, keeping track of which positions you have already used.

The other thing to keep in mind in having found all of the depth combinations, is that not all of them might be valid, due to the Max adjacent cut specification.

That MACS could also be a slight problem for finding all the master pin positions, particularly if your original key already has a 0 cut or a 9 cut in a given position.  In which case,  you will have to abide by the MACS for the neighboring positions, and work around it, like if one position is 95312,  then you can't have a blank with 90312.  Instead,  get a blank cut with 05312,  work that pin, and determine what is present there.

[billrail]

Simple Description and great graphics!
Thank you,

[maximumwoof]

a manager at an employer of mine from years ago, said that masterkeying is for convenience only; it is the organized destruction of security. a way to compensate for that is to use restricted distribution keyways, as well as high security lock cylinders that have a 2 factor security level such as medeco. (other types of 'high security' lock cylinders that operate on different principles are good too.)

[Paladin-Locksmiths]

Very informative and worrying, keep up the good work.

[kksharp]

@SchuylerTowne Small point, but If you had your 32 master "possibles", and one of them worked on another lock, wouldn't you still have to try the remaining 32 and make sure that no other one worked as well? Wouldn't it be possible that the second lock had a chamber that had the same non-master cut?

[Stray]

Heard a replay of an interview with you on CBC radio the other day, seems you got somewhat famous since the days I was frequenting the forum more regularly. The pronounce your name thread and socially engineered solution still makes me laugh when I think about it, good times.

[sweetkellymay]

Awesome video, never knew locks had a top and bottom shear line...

[maximumwoof]

thats why a smarter building manager will do something like have electronic access to a buildings main entries where when a entry credential is missing, it can be 'removed' from the system within a very short time from a computer terminal, online even with some systems. then the tenants can be responsible for the keying of their own doors, subject to managements technical requirements.

[ACCSESS]

Another superb, informative vid, nice1 Schuyler bro.

[TeleTubeee]

Brilliant explanation, Schuyler! You made it easy to follow your logical deductions.

BTW, have you found good locksmiths to be naturally good chess players?

Doug
San Francisco, CA

[MichaelMior]

If you have access to two user keys, then it's much easier to carry out the process with two different locks. Then knowing the possible configurations of the master for each lock, you should find that only one configuration will open both locks. This greatly reduces the number of keys that need to be cut.

[WolfJustWolf]

If the master key system is properly made (not always the case), the change key will not have any bitting in common with the master key. So if you find 1 wafer per chamber, meaning 2 depths per postion, just take the other one than your change key.
If it was a GMK system, you will find additional wafers.
If the system is a partial position progressioning, you will have positions without wafers, there the cut on the master key is the same as on the change keys. Same goes for rotating constant systems.

[FuquarProductions]

I believe the simplest way is just to use a pin calculator that that gives you the bottom pins Master pins stack height and the amount of keys or combinations that will fit it. Lots of free ones online and they even work using your phone

[jimu]

helping a friend that had an office master keyed. he had no documentation and cannot get it. had to take every cylinder apart. good thing. 4 offices were cross keyed to 3 entrance doors that were keyed alike. 4 offices used up 30 possible 6 pin bittings for the cross keying. One chamber in an entrance doors has 4 master wafers. 2 others have 2 wafers. sometimes you have to take them apart not matter what.

[smeado]

Just rekeyed a house for a client in a development that's about 7 years old yesterday. The house had the original Kwikset locks and has never been rekeyed. I realized the original locks were master keyed and in about 5 minutes was able to compare the homeowner's key and the pin measurements and had the master key combination. I could probably make that key and open every house in the development that hasn't been rekeyed. Pretty irresponsible of the builder to do that to the residents of that neighborhood. By the way, I'm not even a locksmith.