Verify on arrival
The single highest value habit here, and the one most likely to fall off the routine because it produces no visible result.
Before you can use it
You need a fingerprint established independently and stored where you control it. Without one this check proves nothing, because a signature verified against a key taken from the page being checked is a page vouching for itself, and internal consistency costs a forger nothing.
Collect it from several sources that would have to be compromised separately, compare it in full rather than the ends, and write it down. About an hour, once. Three pages by one operator count as one source, and three that copied a fourth also count as one.
The procedure
- Find the signed block. It begins and ends with the armour lines. No signed block means the answer is no.
- Copy all of it. Nothing trimmed, no whitespace altered. A partial copy fails in a way that looks identical to tampering.
- Check against your pinned fingerprint, never a key the page offers.
- Read the output. Both which key signed and the date inside the signed text.
The four results
| Result | Meaning | Do |
|---|---|---|
| Bad signature | Text altered or fabricated | Leave. Unambiguous. |
| No public key | Signed by a key you do not hold | Import the right one after checking its fingerprint, never one the page offers. |
| Good, unexpected key | Maths works against a key that is not yours | Leave. The word good appears, which is why this catches people. |
| Good, old date | Verifies, statement is months old | Treat as unconfirmed. Signatures never expire, so old genuine ones get replayed. |
What it does not reach
Whether the signer is honest, whether your own machine is trustworthy, and anything that happens after you log in. It answers one question completely and no others, which is exactly why it is worth doing and why the other five habits exist.
What a signature proves, exactly
Two things, narrowly and completely: that whoever produced the block held a specific private key, and that the text has not changed since. It does not prove the signer is honest, that the key still belongs to the same people, or that the statement is current. Those limits are not weaknesses. They are what makes the guarantee worth anything, because a check that claimed to answer everything would be answering nothing.
Collecting the fingerprint, which is the hard part
- Gather it from sources that would have to be compromised separately. Three pages run by one operator are one source.
- Compare in full, not the first and last few characters.
- Write it down outside the browser, in a file or on paper you control.
- Note the date you pinned it, so a future change is a change rather than a vague impression.
Why it falls out of the routine
Because it succeeds silently. Every session where the check passes feels like a minute wasted, and after a hundred of those the habit erodes on its own without any decision being made. The people who lose accounts this way are usually not people who never checked. They are people who checked for a year and then stopped, and the evening it mattered looked exactly like the hundred that did not.