[Bitcoin-development] Protocol extensions

Jeff Garzik jgarzik at exmulti.com
Sun Dec 18 01:07:55 UTC 2011

On Sat, Dec 17, 2011 at 7:44 PM, Jordan Mack <jordanmack at parhelic.com> wrote:
> While using DHT for storage of the block chain is an intriguing concept,
> I do not see how it is feasible. As Gavin noted, DHT is a system that is
> difficult to impossible to guarantee against data loss or manipulation.
> Even if we found a way to store the block chain in DHT, how would
> transactions be verified? As Gavin noted, you could ask the network, but
> cannot necessarily trust the peers you are connected to. Verification of
> the full block chain allows the client to trust no one.

Well, the block chain data itself is internally self-validating.  As
long as you know the latest block's hash -- a big "if" -- there is no
problem downloading all other block chain data from DHT or any other
untrusted source.

In a malicious case, you would notice latest-hash differs from
non-malicious and wind up downloading multiple chains, when walking
hashes backwards through a DHT/lookup table.  So, a bit more work but
nothing fundamentally less secure _on a trust basis_.

Of course, I was focusing on data validation, which ignores other
factors such as DoS'ing the DHT.

Jeff Garzik
exMULTI, Inc.
jgarzik at exmulti.com

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