I broke the key while trying to fix it

The program said "who are you — you cannot come in."

I asked why, and nothing came back. An empty answer.

The key was stored in a strange shape

Computers have a safe for keeping secrets. I had put the key in there.

When I took it out, the key was not letters but a pile of numbers. Converting the numbers back to letters one at a time gave me the front of the original key.

The cause was that a single line break had gone in with it. When that happens, this safe hands back a pile of numbers instead of letters.

Trying to fix it broke it

I turned the numbers back into letters and put it into the safe again. I chose the option "type it in without showing it on screen." It seemed safer, after all.

That option cuts off at 128 characters.

My key was 192 characters. Sixty-four vanished, and the original was overwritten. I had to get a brand new key issued.

I had written in another document that "typing it in hidden is safer, so I recommend it." That advice had never checked this 128-character limit.

I chose the safer option, and that option cut the data without saying a word.

The real cause was somewhere else

Thinking about it, breaking the key was the result.

The cause was that nothing told me why it was failing. Four different things can go wrong, and on screen all four looked like the same "who are you — you cannot come in."

• the key does not have enough permission
• the key was cut off at 128 characters
• a line break got in and turned it into a pile of numbers
• the "only look at this room" list is empty

When four things wear the same face, the cause becomes a guess. And the guess turned fixing into breaking.

So I built a checker

It recognises all four, and tells me the exact command to run.

✖ Key shape: looks like a pile of numbers (386 characters)
   command to fix it: (copy and paste as is)
✖ Check: could not get in

When permission is missing, it reads the list the server already gave while refusing. It does not guess from an empty answer.

And the checker never prints the key in any form. It does not even include the first few characters — it answers only "yes" or "no." A test even confirms no piece of the key leaked into the answer.

What cannot be fixed

At the moment the key goes into the safe, the value can briefly be seen elsewhere. The thing that removes that is exactly the hidden typing — which cuts at 128 characters.

My key is longer than that. So I took the briefly-visible route, and wrote that fact down.

The most dangerous moment is the first time you use a repair procedure. Even more so if the procedure overwrites the original.