email Crypto- third party

[Pete Bentley]

At Tue, 03 Aug 1999 10:57:22 BST, Ben Laurie writes:
>> Fax receivers and transmitters co-operate just as modems do over fast links
>> (V34, V56, V90), which means that an unintended recipient of a fax cannot
>> simply use normal receiving hardware and software, but has to interpret the
>> two way exchange between the terminals, from the intermediate
>> position.  The buzzword for this is "blind demodulation".
>
>I thought only more modern faxes did that. But I could be wrong.

I don't have a reference to hand, but from memory all fax modulation
schemes up to 14K4 are half duplex, which makes the demodulation part
of the problem easier (compared to, say, data schemes like V.32 and
faster).  You would probably still need to interpret the two way
exhange at the start of the conversation where the machines swap
capabilities and decide on data formats to make sense of the bytes you 
captured though.

Pete.