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Re: Subject: OT: LUKS encryption -- block by block, file by file, or "one big lump"

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On 3/9/23 06:53, rhkramer@gmail.com wrote:
> Thanks to all who replied -- two clarifications requested below:
> 
> On Wednesday, March 08, 2023 09:45:33 PM David Christensen wrote:
> ...
>> A few years ago, I did a "bit rot" experiment.
> 
> Thanks for doing that experiment!
> 
> ...
> 
>> I wiped a disk, applied
>> a partitioning scheme, created a partition, formatted the partition with
>> LUKS (with default encryption), opened the LUKS container, created an
>> ext4 filesystem, mounted the filesystem, and wrote a large file
>> containing a predictable pattern.  I used hexdump(1) to find the
>> encrypted blocks on disk that corresponded to the file.  I used dd(1) to
>> write directly to the disk and change some portion of a block underlying
>> the file.  I then viewed the file contents with standard userland tools
>> (e.g. less(1)).  To my dismay, the tools could read the file without
>> error and the file contents were corrupt!
> 
> Just so I'm clear on that last sentence, what you're saying is that less was
> able to read the file (view the content) but the file / content was corrupt?
> 
> And, was it the entire file that was corrupt?
> 
>> I seem to recall that the
>> number of damaged bytes was the same on disc and in the file.
> 
> Maybe that answered my question -- I guess that is saying that only a few
> bytes in the file were corrupt, and they were localized to one portion of the
> file?
> 
> Thanks!


I believe I changed a byte somewhere in the middle of file blocks on 
disk using dd(1) and then I saw a bad byte somewhere in the middle of 
the file with less(1).


I suggest that you repeat the experiment.  Just going through the 
process will give you a better understanding of the steps involved and 
the tools used.


David

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Subject: OT: LUKS encryption -- block by block, file by file, or "one big lump" rhkramer@gmail.com - 2023-03-08 16:30 +0100
  Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" <tomas@tuxteam.de> - 2023-03-08 18:20 +0100
    Re: Subject: OT: LUKS encryption -- block by block, file by file,          or "one big lump" Linux-Fan <Ma_Sys.ma@web.de> - 2023-03-08 22:10 +0100
  Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" David Christensen <dpchrist@holgerdanske.com> - 2023-03-09 03:50 +0100
    Re: Subject: OT: LUKS encryption -- block by block, file by file, or "one big lump" rhkramer@gmail.com - 2023-03-09 16:00 +0100
      Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" David Christensen <dpchrist@holgerdanske.com> - 2023-03-09 22:10 +0100
        Re: Subject: OT: LUKS encryption -- block by block, file by file, or "one big lump" rhkramer@gmail.com - 2023-03-10 01:30 +0100
  Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" Nicolas George <george@nsup.org> - 2023-03-09 22:20 +0100
    Re: Subject: OT: LUKS encryption -- block by block, file by file, or "one big lump" rhkramer@gmail.com - 2023-03-10 01:30 +0100
      Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" Nicolas George <george@nsup.org> - 2023-03-10 09:00 +0100
        Re: Subject: OT: LUKS encryption -- block by block, file by file, or "one big lump" rhkramer@gmail.com - 2023-03-10 13:30 +0100
    Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" "Bottenberg, Michael" <michael@der-he.de> - 2023-03-10 17:00 +0100
      Re: Subject: OT: LUKS encryption -- block by block, file by file, or  "one big lump" Nicolas George <george@nsup.org> - 2023-03-10 17:10 +0100

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