Smart Lock Codes and Guest Access

How do I give someone a smart lock code?

In the lock's app: add a user, set a code, and attach a time limit — permanent, a recurring schedule, or a single use. The part nobody explains is delivery. The code has to be written into the lock itself, because the keypad is checked by the lock, not by a server. How that write happens is the difference between a code that works tomorrow morning and a code that works the next time you walk past your own front door.

The three kinds of code

Permanent codes are for the household. One per person, never shared, because the whole point of separate codes is that you can remove one without re-teaching everybody a new number.

Scheduled codeswork only inside a window you define — weekdays between nine and five for a cleaner, or a single weekend for a visitor. This is the setting most people never find and the one that makes the feature genuinely useful, because access expires on its own instead of relying on you to remember to revoke it.

One-time or duration codes are consumed on first use or after a fixed period. These are what you send a delivery, a contractor or a guest arriving at an unknown hour. Not every lock supports them, and the ones that do implement them differently: some expire on first entry, some on a timer, some both.

How a code gets from the app to the lock

This is the mechanism, and it is the only part of this page worth memorizing. The keypad on your door is verified by the lock's own processor against codes stored in the lock. Nothing phones home when somebody types a number — which is exactly why codes keep working when your internet is down. The consequence is that a new code must be transmitted to the lock before it exists at the door, and there are three ways that happens:

The failure case is the fourth row and it is common, because plenty of locks are sold as “smart” on Bluetooth alone. You create the code on the train, the app accepts it, and the lock never hears about it. The bridge question is the same one that decides whether you can check the lock at all from away, which is covered in do smart locks need wifi.

What happens when the lock is offline

Existing codes keep working. That is the single most reassuring fact about this category and it follows directly from the mechanism above: the lock checks the keypad itself, so an internet outage, a dead router or a vendor's server problem does not stop anybody getting in with a code they already have.

What stops working is management. You cannot add, change or revoke a code, you will not get an entry notification, and the access log will be filled in later rather than live. If you are relying on scheduled access for a cleaner on a Monday morning, that schedule is already stored in the lock and will hold — but a last-minute change will not reach it. The general offline behavior of locks is in do smart locks work in a power outage.

Revoking access without annoying everybody

Give every person their own code from day one. It takes two extra minutes and it means withdrawing one person's access is a single deletion rather than a household-wide re-education. If you have been sharing one code, change it once and issue individual codes at the same time; doing it in one pass is less painful than doing it twice.

Two more habits worth building. Use the access log: most connected locks record which code opened the door and when, which is the only way to notice that a code you thought was retired is still in use. And treat a departed housekeeper, tenant or ex-partner as a code deletion plus a cylinder decision — if they ever had a physical key, deleting a code does nothing about it. Kwikset's SmartKey line lets you re-key the cylinder yourself in about a minute, which is the one genuinely useful answer to a missing key, with the published trade-off noted in are smart locks safe.

Keypad hygiene: smudges, shoulders and anti-peek

A fixed keypad leaks its code two ways. Wear and finger grease concentrate on the four digits in use, and anyone standing behind a guest can read the sequence. Three mitigations, in order of how much they cost:

• Anti-peek entry— several locks let you pad the real code with junk digits, so what an observer sees is longer than the code and contains it. Free, and it works.
• Rotate codes— particularly the ones given to a rotating cast of guests or contractors. A scheduled code that expires does this for you.
• A scrambling keypad— the digit positions move on every use, which defeats both smudge and shoulder attacks outright. The cost is speed and usability for every single entry, and it is a poor choice for a household with a child or an older relative, as the lock rankings for older parents set out.