[ubuntu-uk] Reverse engineering data files

Paul Sladen ubuntu at paul.sladen.org
Mon Nov 24 17:52:40 UTC 2014

On Mon, 24 Nov 2014, Gareth France wrote:
> www.cliftonts.co.uk/SSS
> the possibility of being given the design specs and signing a
> non-disclosure agreement.

I wouldn't bother waiting nor risk the complications arising from
signing an agreement.  You're doing something for the purposes of
interoperability, and the format seems so simple---running:

  strings SSS

gets you most of the content;  viewing the file itself with:

  hexdump -C SSS | less -S

It appears records are 180 bytes each.
Each record starts with 0xae and ends with 0xff.
Most strings appears to be a 16-byte fixed width, and zero-padded.
'I010000022S12111' is just a text-string; you should be able to match
up to what was displayed on-screen the meaning of each character.

The only binary data I can see is

   0b 2c 03 06 07

Which I presume is hour, minute, day, month, year+2007; so in this

  11:44 3 JUN 2014.

For figuring out the test string itself, I suggest you engineer a
number of 'failures' and see what changes between each one.

Hope that helps!


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