Picking masterkeyed locks?

[eezacque]

So, the pins of a masterkeyed lock consist of three parts. Does this mean that, say for a lock with 6 pins, there are 2^6 possible keys? Also, can a trained picker feel whether a lock has a master key?

[GWiens2001]

First part of your question - yes. Your math is correct. One master pin in each pin channel would create 2^6 (64) keys that will operate the lock. That is why the best description of master keying I've ever heard (by member Sinifar) is "Master keying is the controlled destruction of security." Every pin stack that has a single master pin doubles the number of keys that will work in the lock. The pin stacks with multiple master pins obviously create more permutions and increase the number of keys respectively to the number of pins.

Many of those locksmiths who are more skilled at master keying design their systems to use as few master pins as possible.

The second part of your question is yes... if they are looking for it. If the picker, no matter how skilled, only wants to get the lock open, then they won't care about whether it is master keyed or not, except to realize it will be easier to open. If they are checking to see if it is master keyed without taking apart the lock, then it can be done.

Clearly, the more key permutations that can operate a lock, the easier it is to pick the lock. That is why I roll my eyes when a customer who has a single lock on the front of their store says "I have my lock heavily master keyed because my previous locksmith explained how much it increases security".

Yes, there are least three locksmiths here in town who do that. One of them puts 2-4 master pins in every pin channel. Simple rule of thumb... if you have only one lock or only need one key to operate the lock - - - DO NOT MASTER KEY THE LOCK!!!

*** Steps off my soap box ***

Gordon

[RedStagKiller]

First part of your question - yes. Your math is correct. One master pin in each pin channel would create 2^6 (64) keys that will operate the lock. That is why the best description of master keying I've ever heard (by member Sinifar) is "Master keying is the controlled destruction of security." Every pin stack that has a single master pin doubles the number of keys that will work in the lock. The pin stacks with multiple master pins obviously create more permutions and increase the number of keys respectively to the number of pins.

Many of those locksmiths who are more skilled at master keying design their systems to use as few master pins as possible.

The second part of your question is yes... if they are looking for it. If the picker, no matter how skilled, only wants to get the lock open, then they won't care about whether it is master keyed or not, except to realize it will be easier to open. If they are checking to see if it is master keyed without taking apart the lock, then it can be done.

Clearly, the more key permutations that can operate a lock, the easier it is to pick the lock. That is why I roll my eyes when a customer who has a single lock on the front of their store says "I have my lock heavily master keyed because my previous locksmith explained how much it increases security".

Yes, there are least three locksmiths here in town who do that. One of them puts 2-4 master pins in every pin channel. Simple rule of thumb... if you have only one lock or only need one key to operate the lock - - - DO NOT MASTER KEY THE LOCK!!!

*** Steps off my soap box ***

Gordon

I love it when an someone gives us a keying schedule with subs and multiple change keys (you've explained to them the security issues). You key it up and then a month later they ask for 20 master keys...

[GWiens2001]

Agreed. Why did they bother master keying at all if they were just going to hand out master keys like they were candy?

Gordon

[billdeserthills]

Agreed. Why did they bother master keying at all if they were just going to hand out master keys like they were candy?

Gordon

Because having a master key sounds so cool?

[eezacque]

Thanks for the comprehensive answer!

[Jacob Morgan]

The Corbin Russwin master ring system might be of interest to you, in terms of how it makes a master-keyed cylinder harder to pick versus the usual master-keyed cylinders. If you do a web search for it you can find the literature on it, but basically there is a sleeve around the cylinder and the change key and master key use different shear lines. If some pins are at one shear lines and others are at the other shear line the cylinder will not open.

[GWiens2001]

The Corbin Russwin master ring system might be of interest to you, in terms of how it makes a master-keyed cylinder harder to pick versus the usual master-keyed cylinders. If you do a web search for it you can find the literature on it, but basically there is a sleeve around the cylinder and the change key and master key use different shear lines. If some pins are at one shear lines and others are at the other shear line the cylinder will not open.

Exactly like picking a Best SFIC. Just that the Corbin Master Ring makes the ring go all the way around the plug, while in an SFIC, the ring for the control lug only moves about 15 degrees before stopping. Still, you have the two shear lines breaching the same pin channels.

Gordon