bitcoinj-0.10 release notes:

   - We now require Bloom-capable (0.8+) peers by default and will
   disconnect from older nodes. This avoids accidental bandwidth saturation on
   mobile devices.

Given the user-security concern that Peter brings up, reconsideration of
this new default behavior in SPV clients may be warranted.



On Fri, Aug 16, 2013 at 4:15 AM, Peter Todd <pete@petertodd.org> wrote:

> On Fri, Aug 16, 2013 at 10:01:16AM -0400, Peter Todd wrote:
> > Doing this also makes it more difficult to sybil the network - for
> > instance right now you can create "SPV honeypots" that allow incoming
> > connections only from SPV nodes, thus attracting a disproportionate % of
> > the total SPV population given a relatively small number of nodes. You
> > can then use that to harm SPV nodes by, for instance, making a % of
> > transactions be dropped deterministicly, either by the bloom matching
> > code, or when sent. Users unlucky enough to be surrounded by sybil nodes
> > will have their transactions mysteriously fail to arrive in their
> > wallets, or have their transactions mysteriously never confirm. Given
> > how few full nodes there are, it probably won't take very many honeypots
> > to pull off this attack, especially if you combine it with a
> > simultaneous max connections or bloom io attack to degrade the capacity
> > of honest nodes.
>
> Oh, here's an even better way to do the "tx drop" attack: when you drop
> a transaction, make a fake one that pays the same scriptPubKeys with the
> same amount, and send it to the SPV peer instead. They'll see the
> transaction go through and show up in their wallet, but it'll look like
> it got stuck and never confirmed. They'll soon wind up with a wallet
> full of useless transactions, effectively locking them out of their
> money.
>
> Here's another question for you Mike: So does bitcoinj have any
> protections against peers flooding you with useless garbage? It'd be
> easy to rack up a user's data bill for instance by just creating junk
> unconfirmed transactions matching the bloom filter.
>
> --
> 'peter'[:-1]@petertodd.org
> 0000000000000018dcf5bcc3f018a05517ba1c479b432ba422015d4506496e55
>
>
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