[ubuntu-uk] Reverse engineering data files

[Paul Sladen]

On Tue, 25 Nov 2014, Paul Sladen wrote:
> On Mon, 24 Nov 2014, Gareth France wrote:
> > Sounds good. The tricky bit is they seem to have encrypted the results 
> There doesn't appear to be anything encrypted. 

A newer '.sss' version (found packed inside a '.gar' container format)
does appear to have been obfuscated: adding/subtracting a certain
amount to each byte from the output of a xorshift PNR, seeded from the
file-headers supplied immediately before the compressed stream:

  https://github.com/sladen/pat/blob/master/gar.py#L130
  https://en.wikipedia.org/wiki/Xorshift

Obfuscation (as found here) is not encryption.  But neither is ROT13
encryption either:

  https://en.wikipedia.org/wiki/ROT13

	-Paul