[p2p-hackers] [connellybarnes@yahoo.com: [i2p] Python filesharing Merkle hash tree magic]

[Nick Johnson]

How does this work? You don't provide details here or in the .py file - 
does each chunk include the hashes of all its siblings, and its parents' 
siblings, etc?

-Nick Johnson

Eugen Leitl wrote:

>----- Forwarded message from "C. Barnes" <connellybarnes at yahoo.com> -----
>
>From: "C. Barnes" <connellybarnes at yahoo.com>
>Date: Thu, 12 May 2005 04:36:32 -0700 (PDT)
>To: i2p at i2p.net
>Subject: [i2p] Python filesharing Merkle hash tree magic
>
>
>Topic: P2P filesharing ala BitTorrent.
>
>Presenting public domain module 'chunk.py':
>
>  http://oregonstate.edu/~barnesc/temp/chunk.py
>
>This module does some magic with Merkle hash trees.
>It allows one to publish a 20 byte SHA-1 digest for
>a file, and encode 'chunks' from the file with
>minimal overhead, such that any given chunk can be
>verified against the file's 20 byte digest.
>Cryptographic hashing is used to verify each chunk,
>so chunks can be transmitted in any order, and it is
>impossible to save corrupt data to disk if one has
>the correct file hash.
>
>One could use this module in any file sharing
>application which divides files up into blocks.
>
>For example, in a BitTorrent-like project it might
>be desirable to keep the .torrent files minimal in
>size.  Using this module, one needs to only publish
>a hash like DA39A3EE5E6B4B0D3255BFEF95601890AFD80709
>instead of a digest of all blocks in the file.
>
>Pros:
> - Smaller digest size.
> - Can send chunks in any order.
>
>Cons:
> - Each 'chunk' contains checksumming information.
>   This overhead is less than 4% for files of size
>   less than 1e20 bytes.
>
> - Connelly Barnes
>
>
>
>		
>__________________________________ 
>Yahoo! Mail Mobile 
>Take Yahoo! Mail with you! Check email on your mobile phone. 
>http://mobile.yahoo.com/learn/mail 
>_______________________________________________
>i2p mailing list
>i2p at i2p.net
>http://i2p.dnsalias.net/mailman/listinfo/i2p
>
>----- End forwarded message -----
>_______________________________________________
>p2p-hackers mailing list
>p2p-hackers at zgp.org
>http://zgp.org/mailman/listinfo/p2p-hackers
>_______________________________________________
>Here is a web page listing P2P Conferences:
>http://www.neurogrid.net/twiki/bin/view/Main/PeerToPeerConferences
>
>!DSPAM:4285c8e4292214151599692!
>
>  
>