Number of Master Pins

[the_hacker]

Hello everyone,

I havea question regarding master keying. I am designing a very small system consisting of about 5 different keys using 6-pin Sargent cylinders.

I have used a program to develop the system but I am unsure of how many chambers should hold master pins and where. I figure that the less master pins there are, the more similar each key is and therefore the easier it is to get to the next "level" by filing down the key. On the other hand, it is more secure in that it has less master pins overall.

What would you say the best trade-off is between the key filing security risk and the master pinning security risk ?

Thanks!

[keysman]

What would you say the best trade-off is between the key filing security risk and the master pinning security risk ?

Thanks!

Just make sure the Master is cut higher than the change key in at least 1 position .. filing won't work.

[Evan]

I have a question regarding master keying. I am designing a very small system consisting of about 5 different keys using 6-pin Sargent cylinders.

I have used a program to develop the system but I am unsure of how many chambers should hold master pins and where. I figure that the less master pins there are, the more similar each key is and therefore the easier it is to get to the next "level" by filing down the key. On the other hand, it is more secure in that it has less master pins overall.

@the_hacker:

What program did you use to develop the master key system in question ?

Your concerns about how many chambers should hold master pins is one which is determined by deciding between using either the "Total Position Progression" method in which every chamber requires a master pin since no change key can share any of the cuts on the system top master key OR using the "Rotating Constant" method in which change keys share some of the cuts of the system top master key...

Detailed discussion of how to select a master key bitting combination and what a small sample Total Position Progression method master key system looks like can be found in this thread:

LP101 > Locksmith Business Information > Master Keying Systems

If you would like to see an example of a Rotating Constant method master key system just reply here and I will post one in the above referenced topic thread...

~~ Evan

[the_hacker]

Just make sure the Master is cut higher than the change key in at least 1 position .. filing won't work.

It's not really the shaving of the key to become a master that's my concern but I'm thinking that if the fewest number of chambers has master pins (1), one could theoretically very quickly file down the key for one-time access to another room whose key is cut deeper.

[quote="Evan
What program did you use to develop the master key system in question ?

Your concerns about how many chambers should hold master pins is one which is determined by deciding between using either the "Total Position Progression" method in which every chamber requires a master pin since no change key can share any of the cuts on the system top master key OR using the "Rotating Constant" method in which change keys share some of the cuts of the system top master key...

Detailed discussion of how to select a master key bitting combination and what a small sample Total Position Progression method master key system looks like can be found in this thread:

LP101 > Locksmith Business Information > Master Keying Systems

If you would like to see an example of a Rotating Constant method master key system just reply here and I will post one in the above referenced topic thread...

~~ Evan[/quote]

The program I used is called "Master Key Plus" for DOS. I used the "Rotating Constant" method and I found that as long as each change key has a master pin in a different chamber (which is feasable with a small system such as this one) the filing risk to access a different door is greatly reduced and not much of a concern at all. On top of that, that would mean that any potential lock pickers will have at maximum 2 master pins which probably wouldn't help them much in trying to pick the door.

I understand that lock picking is probably one of the least of my concerns regarding door security but I'd like to minimize any potential security flaws in the lock itself.

Thanks everyone for all your help!

[Evan]

The program I used is called "Master Key Plus" for DOS. I used the "Rotating Constant" method and I found that as long as each change key has a master pin in a different chamber (which is feasable with a small system such as this one) the filing risk to access a different door is greatly reduced and not much of a concern at all. On top of that, that would mean that any potential lock pickers will have at maximum 2 master pins which probably wouldn't help them much in trying to pick the door.

I understand that lock picking is probably one of the least of my concerns regarding door security but I'd like to minimize any potential security flaws in the lock itself.

Thanks everyone for all your help!

@the_hacker:

So you are progressing two chambers out of six available in the lock...

Your program should have generated a chart with one master key combination and 240 theoretical change key bittings...

Two chambers progressed, two step-progression, (4 x 4 = 16) using the 15 patterns available (16 x 15 = 240)...

The more chambers you progress the more theoretical key bittings you can generate in your system...

Other than asking in a very superfluous way whether or not using master pins in two chambers of a six pin lock represents a security risk/flaw/etc which can be exploited what were you getting at exactly ?

Pick the progression patterns to use where the master key bitting in one of the chambers of the lock is shallower than all of the change keys and it seems your biggest problem/issue would be moot... You only say you need 6 change keys, each pattern of the 15 permutations of progressing two pin chambers produces 16 theoretical change keys... Pick two bittings each from three different patterns (keeping the one chamber where the master key has the shallowest cut in each of the patterns you use) and the keys will look sufficiently different so that it would not be readily apparent what method of creating the system you used to someone who can see all 6 of your change keys... If you used all 6 bittings from one particular pattern all of the change keys from that pattern would have 3 identical cuts shared with the master key and someone who knows about master keying would have a good idea what method was used to create the system...

~~ Evan

[Evan]

If you used all 6 bittings from one particular pattern all of the change keys from that pattern would have 3 identical cuts shared with the master key and someone who knows about master keying would have a good idea what method was used to create the system...

EDIT: If you used 6 bittings from the same progression pattern you would have keys that have 4 identical cuts on them which are the shared bittings from the master key...

[the_hacker]

So you are progressing two chambers out of six available in the lock...

Your program should have generated a chart with one master key combination and 240 theoretical change key bittings...

Two chambers progressed, two step-progression, (4 x 4 = 16) using the 15 patterns available (16 x 15 = 240)...

The more chambers you progress the more theoretical key bittings you can generate in your system...

Other than asking in a very superfluous way whether or not using master pins in two chambers of a six pin lock represents a security risk/flaw/etc which can be exploited what were you getting at exactly ?


~~ Evan

Hi Evan,

Sorry for the late reply, I almost forgot I had a thread on here!

I'm not sure if this is what you were asking about, but the issue with how many master pins to use developed from my knowledge that if I use more master pins, all the keys are guaranteed to look different (making it difficult to determine which pins are masters) but that gives someone picking the lock easier access due to many/all chambers having multiple shear lines (master pins). I'm trying to figure out what the optimal constant/variable ratio is for my system.

I think it's safe to say that as long as the 2 master pins are in different chambers for each change key I shouldn't have any issues with people being able to figure out that, for example, two particular chambers are used for the entire system, due to the small size of this system.

I'm quite new to master keying so if there's anything you would change about what I'm doing please let me know.

Thanks!

[maintenanceguy]

for what you're trying to do: master pins in 2 pin stacks is going to work.

[Evan]

I'm not sure if this is what you were asking about, but the issue with how many master pins to use developed from my knowledge that if I use more master pins, all the keys are guaranteed to look different (making it difficult to determine which pins are masters) but that gives someone picking the lock easier access due to many/all chambers having multiple shear lines (master pins). I'm trying to figure out what the optimal constant/variable ratio is for my system.

I think it's safe to say that as long as the 2 master pins are in different chambers for each change key I shouldn't have any issues with people being able to figure out that, for example, two particular chambers are used for the entire system, due to the small size of this system.

I'm quite new to master keying so if there's anything you would change about what I'm doing please let me know.

@the_hacker:

It is more complex than simply just having the two chambers with the master pins in them be in different locations in the lock... Since a chamber either is pinned to the master bitting only (constant) or is pinned to the master bitting and a change key bitting (progressed) you must use one of the 15 available Rotating Constant patterns for 6-pin cylinders where 2 chambers are progreesed... Called a "2-in-6"... If you don't follow the patterns you can create unintended key interchange within your system...

By selecting bittings to use from different patterns of progression, you would avoid having keys that look identical except in two positions... Someone with access to the keys could determine the type of system if they knew about master keying if you picked all six change keys from the same pattern...

Example:

TMK:
4 9 6 1 2 5
6 1 8 3 4 7
8 3 0 5 6 9
0 5 2 7 8 1
2 7 4 9 0 3

2-in-6 Progression Patterns:
# 01: C C C C P P
# 02: C C C P C P
# 03: C C C P P C
# 04: C C P C C P
# 05: C C P C P C
# 06: C P P C C C
# 07: C P C C C P
# 08: C P C C P C
# 09: C P C P C C
# 10: C P P C C C
# 11: P C C C C P
# 12: P C C C P C
# 13: P C C P C C
# 14: P C P C C C
# 15: P P C C C C

Change keys chosen from patterns 1 or 15 would look like they are from a normal total position progression method keying system... Keys from other patterns would look strange and would clue someone with master keying experience in as to which method of creating the system was used...

It sounds to me like you are too hung up on worrying about cylinder security versus master keying... You should use more expensive patented high security cylinders with key control for your system if security is your concern...

~~ Evan

[the_hacker]

Thanks a lot Evan! All the information you've given me will definitely help me in creating a master system, I'll have to study it a bit and I'll post back if I have any more questions.

Thanks again!