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RE: st: RE: RE: Encryption of data


From   "Nick Cox" <[email protected]>
To   <[email protected]>
Subject   RE: st: RE: RE: Encryption of data
Date   Wed, 13 Jun 2007 17:12:57 +0100

There is a minute but non-zero chance of ties
on numbers drawn using -uniform()-. In principle 
we are drawing from a continuous distribution, but 
in practice, numbers are held to finite precision. 

Thus an industrial-strength algorithm would need to 
break ties consistently. 

Nick 
[email protected] 

Maarten Buis
 
> Can't you do that like this?
> 
> *------------ begin example -----------
> tempfile a b
> sysuse auto, clear
> gen key = uniform()
> 
> preserve
> drop make
> save `a'
> restore
> 
> keep make key
> sort key
> save `b'
> 
> use `a', clear
> sort key
> merge key using `b'
> *----------- end example ------------
> (For more on how to use examples I sent to the Statalist, see
> http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
> 
> So what you give others is a dataset with a key that is a 
> random draw from a uniform distribution, and if you need the 
> data you wanted to hide you can merge that data back in by 
> using that key.

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