Re: Brute Force attack Question (basic)

[morgan@keilin.helsinki.fi (Joel Morgan)]

Perry E. Metzger writes:
> 
> Igor Chudov writes:
> > What is Alice and Bob decide to obscure their letters and add random
> > NON-ASCII  characters at random places?
> 
> Assuming I'm using a statistics based technique, that won't help.
> 

Some fairly basic questions:

1) Is a statistical test like this done on the net composition of the
   whole message or locally, point by point throughout the text (for
   example, using a window)?

2) If what's tested is the net composition of the message, could you
   choose padding to normalize a message back to an apparently random
   distribution?

3) What kind of computation overhead does this statistical testing
   impose (compared to what would be needed for a known-plaintext
   search)?

Thanks,

Joel/ 

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