secure fax (Re: email Crypto- third party)

[Andreas Bogk]

Tom.A.Parker@icl.com writes:

> apparent messages. However you can't do a straight overlay because it
> doesn't give an XOR. 
> 
> Black + Black = Black 
> Black + White = Black as well.

Try arrays of size 2x2, with the following patterns:

0x                 x0
x0 for a 0, and    0x for a 1.

Andreas

-- 
"We show that all proposed quantum bit commitment schemes are insecure because
the sender, Alice, can almost always cheat successfully by using an
Einstein-Podolsky-Rosen type of attack and delaying her measurement until she
opens her commitment." ( http://xxx.lanl.gov/abs/quant-ph/9603004 )