I'm pretty sure that the onion address is generated directly from the private 
key, at least if you have every played around with scallion or eschalot. So 
what you just wrote doesn't apply in that way. But again, I could be wrong. 

> On Mar 4, 2016, at 3:52 PM, Seth David Schoen <sch...@eff.org> wrote:
> 
> Scfith Rise up writes:
> 
>> It _would_ be the same private key. Good luck with generating 1.2 septillion 
>> permutations (16^32). 
> 
> This would be true if the public key were used directly as the onion name
> (which might be possible in certain elliptic curve systems because keys
> are so small).
> 
> But in this case, the onion name is calculated from a hash of the public
> key, and the size of the hash is much smaller than the size of the
> underlying pubkey (80 bits vs. 1024 bits).  The pigeonhole principle
> requires that many, many different pubkeys must have the same hash --
> on average, about 2⁹⁴⁴ pubkeys would have the same hash.  When you
> get a perfect collision from scallion, after doing that 2⁸⁰ work
> (analogous to about 11 days of entire work of the Bitcoin network --
> which you can think of as surprisingly much or surprisingly little work),
> you're still astronomically unlikely to have the same private key!
> 
> -- 
> Seth Schoen  <sch...@eff.org>
> Senior Staff Technologist                       https://www.eff.org/
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