[ubuntu-uk] Reverse engineering data files

Gareth France gareth.france at cliftonts.co.uk
Fri Jan 2 16:37:56 UTC 2015

I've got my new Primetest 300 tester today. I was rather peeved to 
discover is ONLY downloads via bluetooth. Having purchased a dongle it 
refused to connect. The bluetooth manager would flash up a code for me 
to use for a fraction of a second then tell me it had failed. I did some 
digging and someone suggested installing blueman which worked wonderfully.

However once connected you must then right click and select connect to 
serial service which connects the tester to /dev/rfcomm0. So far so 
good, the problem is the connection times out shortly after but ubuntu 
keeps that port open and I have no idea how to close it so have to 
reboot as the tester refuses to accept that it is connected unless you 
close and re-open that port. Also I am not able to do the download at 
all. It just keeps telling me the connection has timed out.

Using a gtkterm I have monitored the port and three chunks of data are 
transmitted by the tester before it gives up:

1T*YUPrimeTest 300W35-0504�1T*YUPrimeTest 
300W35-0504�1T*YUPrimeTest 300W35-0504�

I can only assume it is expecting a response to this in order to confirm 
the PC is receiving. Any ideas?

On 29/12/14 07:31, Paul Sladen wrote:
> 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

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