Re: Back to Merkle Hash Trees...
Justin Cormack <[email protected]> Sat, 5 Feb 2005 12:28:45 +0000 (GMT)
| Newsgroups | gmane.network.bit-torrent.general |
|---|---|
| Message-ID | <[email protected]> |
>
>
> 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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