[Asterisk-Users] Can I recreate a Fax from a recorded file?

Steve Underwood steveu at coppice.org
Thu May 4 22:05:35 MST 2006


Scott Gifford wrote:

>Colin Anderson <ColinA at landmarkmasterbuilder.com> writes:
>
>  
>
>>>Why not capture the faxes (in or out) in tiff format, instead of audio
>>>format?  Setup your asterisk box to relay faxes!
>>>      
>>>
>>I think in this case the impact on the client would be much greater if you
>>can show them a recreation of the image from the raw data; you could always
>>claim that a TIFF file was altered (which it can be, trivially) but it's
>>pretty much impossible to change the raw audio to your ends unless you are
>>in a Tom Clancy novel. 
>>    
>>
>
>Why is this hard to fake at all?  You send a different fax to your
>system, and replace the Asterisk audio file with the one from the
>altered fax.  Additionally, the client has no realistic way of
>verifying the correctness of your audio-to-fax translation tool; it
>could just as easily output a TIFF file completely different from the
>one that was actually faxed.
>  
>
In most cases, forensic analysis of the audio from another machine would 
easily show it was a fake. It would lack tell-tale fingerprints of the 
true path, unless it was done with extreme care. Certainly using exactly 
the same model of FAX machine that sent the genuine FAX would be a must. 
Not just for the vendor information it sends, but for the fine details 
in how its modems behave. To pass of the altered fax as being from the 
original sender would require careful control of the DSP.

Steve




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