Sargent and Greenleaf (S&G) [https://en.wikipedia.org/wiki/Sargent_%26_Greenleaf] is the largest US based manufacturer of (actual) high security locks, including locks that are UL rated anti-burglary, and Gov't approved for protecting various levels of classified information.

They're definitely not the only one, but they're well known. [https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN31725-AR_380...] is the current (unclassified) standard I believe, Chapter 6 Section II, which points to the 'DoD lock program' [https://exwc.navfac.navy.mil/DoD-Lock-Program/], including their list of approved lock hardware [https://exwc.navfac.navy.mil/DoD-Lock-Program/Security-Hardw...]. Which has many interesting things there.

A classic 'common' example for a commercial safe that needs to be insurable to store significant quantities of cash or jewelry would be one of the group 1R models from the 8500 series [https://sargentandgreenleaf.com/product/8500-series/]

Every lock manufacturer has somewhere in their files a mapping of key codes, manufacturing codes, etc. to the information necessary to duplicate keys or unlock the combination lock for the default combination as it shipped, with VERY few exceptions, all of which are quite expensive. It's required for manufacturing, QA, and after-sales support. Those expensive models all generally require professional lock smiths.

In most cases with combination locks, this allows them to take the serial # (or for 99% of the safes most individuals ever interact with just model number) and know the combination it shipped with. Most folks never change it.

With keyed locks, it allows them to take the key code (usually a 4-8 digit number/alpha string) and produce an identical working version of the key without ever seeing or touching the key. Sometimes these codes are stamped directly on the lock. Sometimes they're stamped directly on the key. For better locks, it will not be present or impossible to access without compromising or unlocking the lock first. Generally, the better the lock the more inconvenient it is and impossible to non-destructively 'fix' if someone loses the key or combo.

It's almost always trivial to decode a key to get that info, and tools are made to do it for almost all types of locks.

Licensed lock smiths with relations with the manufacturer can acquire most (or all) of that information. Usually literal paper code books. Some of this info of course leaks and gets integrated into software.

Some of it gets controlled by the manufacturer so that the locksmith needs to provide per-customer info and they look it up directly, to control distribution.

Those 8500 series locks have resettable combinations, and any competent locksmith will change it as a matter of course before they let a customer use it. But things slip through the cracks, people get lazy, etc.

Many locks (truck/car keys, house keys, etc.) never get changed from whatever they came as from the factory/in the box, and aren't trivially changeable either.

[https://www.youtube.com/watch?v=pqr8lJWlFH0][https://lockcod...

For some examples of what i'm talking about.

It's niche info, so unless you know what you're looking for, Google isn't likely to give you much anything useful.

However, just like Code Signing keys [https://techcrunch.com/2023/07/17/microsoft-lost-keys-govern...], they're bread and butter type targets for any intelligence agency for obvious reasons. Any such agency that HASN'T acquired such information from the big players is... well not competent at their job. Near as I can tell.

And no, no one has told me anything classified. This is all public knowledge. I just get curious sometimes being around those MOS 35 types occasionally, and I like to research random things.