Re: [dm-crypt] Anyone know why I can't access my volumes?

[Arno Wagner <arno@wagner.name>]

On Thu, Oct 24, 2019 at 09:26:11 CEST, Carl-Daniel Hailfinger wrote:
[...] 
> Can you try booting with the old installed kernel and initrd? Usually
> those are kept for some time after an upgrade.

You may also be able to get them from an archive. Most distros keep
older versions arpound for a while.

> Another thing I had to debug recently for a colleague was a failing
> flash medium. There were no read errors, but single bits of the data had
> flipped. 

I had that as well on an USB-stick. An exceptionally bad design 
that obviously did without the checksums that all well-designed 
storage has.

> A unreported bit flip affecting the keyslots would be
> catastrophic AFAICS. 

A single bit will kill the keyslot. If you know it is a single bit 
only, you can try with all bits flipped (around 1M tries taking 
around 2 weeks with 1 sec per try, i.e. all other keyslosts disabled), 
but if it is two bits, you are already pretty much screwed.

> That said, bitflips affecting only the keyslots and
> nothing else would be a strange beast unless this is a really crappy
> SSD. How often do you reboot during normal operation?

It could be a very small number of bits affected. Also, bit-flips
in documents and even software often go unnoticed for a while.
That is why you should allways do a full compare in backups.
I found weak RAM bits, defective HDD connectors, etc. that way
in the past.

Regards,
Arno

-- 
Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno@wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
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