Re: [bitcoin-dev] The new obfuscation patch & GetStats

From: "James O'Beirne" <james.obeirne@gmail.com>
To: Daniel Kraft <d@domob.eu>
Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] The new obfuscation patch & GetStats
Date: Wed, 7 Oct 2015 16:32:03 -0700	[thread overview]
Message-ID: <CAPfvXfLw25J_mXn6b9QO_VDTU3EoVP9zxt7bbN0RF+2coYAdJA@mail.gmail.com> (raw)
In-Reply-To: <56155572.5040501@domob.eu>

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Hey, Daniel.

Patch author here. Thanks for the diligence; I think this indeed may be an
oversight, though I'm going to need to look into a bit more thoroughly at
home. Curious that it didn't fail any of the automated tests.

Correct me if I'm wrong, but the only actual invocation of that method is
here
<https://github.com/bitcoin/bitcoin/blob/master/src/rpcblockchain.cpp#L448>
(and even then, proxied through a few layers of CCoinView-machinery). In
fact, this line
<https://github.com/bitcoin/bitcoin/blob/master/src/coins.cpp#L48> makes me
suspect that the implementation of GetStats you reference may be dead code.

In any case, you raise a good point: if users of CLevelDBWrapper go
directly for the iterator, they run the risk of dealing with obfuscated
data. This should be remedied somehow.

I'll give it more look this evening.

Thanks again for the find,
James

On Wed, Oct 7, 2015 at 10:25 AM, Daniel Kraft via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Hi!
>
> I hope this is not a stupid question, but I thought I'd ask here first
> instead of opening a Github ticket (in case I'm wrong).
>
> With the recently merged "obfuscation" patch, content of the
> "chainstate" LevelDB is obfuscated by XOR'ing against a random "key".
> This is handled by CLevelDBWrapper's Read/Write methods, which probably
> cover most of the usecases.
>
> *However*, shouldn't it also be handled when iterating over the
> database?  In particular, I would expect that the obfuscation key is
> applied before line 119 in txdb.cpp (i. e., while iterating over the
> coin database in CCoinsViewDB::GetStats).
>
> Is there a reason why this need not be done there, or is this an actual
> oversight?
>
> Yours,
> Daniel
>
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