One brief moment, carrying everything that comes after
A pairing ceremony is the process by which two devices establish an initial shared trust — entering a PIN shown on one device into the other, confirming a matching code, tapping one device against another — before any of the actual data they'll later exchange can be trusted. This moment matters disproportionately to how brief and unremarkable it usually looks: everything the devices communicate afterward relies on the trust this initial exchange established, so a weak or bypassable ceremony undermines every later exchange, regardless of how well-secured those later exchanges are on their own.
This is a specific, concrete instance of trust on first use: accepting a claimed identity at the moment of first contact, with no independent way to verify it at that instant, and then holding the pairing to that same trust for every use afterward.
What separates a meaningful ceremony from a rubber stamp
A ceremony that's too easy to complete without genuine physical proximity or explicit human confirmation — pairing that happens automatically, with no visible confirmation step — makes it correspondingly easy for a device that was never supposed to be trusted to slip into that same trusted role instead, simply by being nearby at the right moment. A meaningful ceremony requires a step that's genuinely hard to satisfy accidentally or remotely: physical proximity, an explicit human confirmation, or both together.