[BitTorrent] Back to Merkle Hash Trees...

Justin Cormack justin at street-vision.com
Sat Feb 5 07:28:45 EST 2005


> 
> 
> Elliott Mitchell wrote:
> > One you might think about helping me murder is the "THEX" design various
> > folks have been advocating. THEX distinguishes leaves from internal nodes
> > by appending a byte depending on whether it is leaf or payload; *that*
> > is bogus!  (kills alignment, makes testing expensive)
> 
> It's not. You do not have to put the byte physically in front of the 
> block. You can 'hash' the byte and then the block.

No you cant, sha1 is block based and you cant hash less than a block of
64 bytes at a time. So there is an alignment issue.
 
> And it's required in general because otherwise you couldn't tell the 
> difference between hash data and user data (if you only know the root 
> hash and not the file size).

There are more significant reasons than this I believe you can spoof
blocks if this isnt done.
 
> > http://www.open-content.net/specs/draft-jchapweske-thex-02.html
> > 
> > 


 
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