From: Loi Luu <loi.luuthe@gmail•com>
To: "Raystonn ." <raystonn@hotmail•com>
Cc: Bitcoin Dev <bitcoin-development@lists•sourceforge.net>
Subject: Re: [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit
Date: Tue, 9 Jun 2015 17:33:34 +0800 [thread overview]
Message-ID: <CAJmQggBcAw1u+Pha+67S4bG5FuKx0xi_dTffmEOUHPbwyJU1aA@mail.gmail.com> (raw)
In-Reply-To: <COL131-DS25374BEFA76744E26EB8CBCDBF0@phx.gbl>
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>
> The proposed fix is to add a new rule on how
> fees are handled. Some amount of every fee should be considered as burned
> and can never be spent. I will propose 50% of the fee here, but there may
> be better numbers that can be discovered prior to putting this into place.
> If we'd like miners to continue to collect the same fees after this change,
> we can suggest the default fee per transaction to be doubled
I would propose another practical rule rather than burning 50% of the fee.
For example, you can
credit 50% of the transaction fee to the next block. Thus, the attacker
cannot perform
the attack with 0-fee any more, yet you don't have to double the price of
the TX fee for the fix.
Thanks,
Loi Luu.
On Tue, Jun 9, 2015 at 4:07 AM, Raystonn . <raystonn@hotmail•com> wrote:
> When implemented, the block size limit was put in place to prevent the
> potential for a massive block to be used as an attack to benefit the miner
> of that block. The theory goes that such a massive block would enrich its
> miner by delaying other miners who are now busy downloading and validating
> that huge block. The original miner of that large-block would be free to
> continue hashing the next block, giving it an advantage.
>
> Unfortunately, this block size limit opened a different attack. Prior to
> the limit, any attempt to spam the network by anyone other than someone
> mining their own transactions would have been economically unfeasible. As
> every transaction would have a fee, there would have been a real cost for
> every minute of spam. The end result would have been a transfer of wealth
> from spammer to Bitcoin miners, which would have harmed the spammers and
> encouraged further mining of Bitcoin, a very antifragile outcome.
>
> But now we have the block size limit. Things are very different with this
> feature in place. The beginning of a spam attack on the Bitcoin network
> will incur transaction fees, just like before. But if spam continues at a
> rate exceeding the block size limit long enough for transactions to be
> dropped from mempools, the vast majority of spam transaction fees will
> never
> have to be paid. In fact, as real users gain in desperation and pay higher
> fees to get their transactions through in a timely manner, the spammers
> will
> adjust their fees to minimize the cost of the attack and maximize
> effectiveness. Using this method, they keep their fees at a point that
> causes most of the spam transactions to be dropped without confirmation
> (free spam), while forcing a floor for transaction fees. Thus, while spam
> could be used by attackers to disable the network entirely, by paying
> high-enough fees to actually fill the blocks with spam, it can also be used
> by a single entity to force a transaction fee floor. Real users will be
> forced to pay a transaction fee higher than the majority of the spam to get
> their transactions confirmed. So this is an effective means for a minority
> of miners to force higher fees through spam attacks, even in the face of
> benevolent miners who would not support a higher fee floor by policy.
> Miners would simply have no way to fix this, as they can only put in the
> transactions that will fit under the block size limit.
>
> In the face of such a spam attack, Bitcoin's credibility and usability
> would
> be severely undermined. The block size limit enables this attack, and I
> now
> argue for its removal. But we can't just remove it and ignore the problem
> that it was intended to address. We need a new fix for the large-block
> problem described in the first paragraph that does not suffer from the
> dropped-transaction spam-attack problem that is enabled by the block size
> limit today. My proposal is likely to be controversial, and I'm very much
> open to hearing other better proposals.
>
> Large blocks created by a miner as a means to spam other miners out of
> competition is a problem because miners do not pay fees for their own
> transactions when they mine them. They collect the fees they pay. This
> breaks the economic barrier keeping people from spamming the network, as
> the
> spamming is essentially free. The proposed fix is to add a new rule on how
> fees are handled. Some amount of every fee should be considered as burned
> and can never be spent. I will propose 50% of the fee here, but there may
> be better numbers that can be discovered prior to putting this into place.
> If we'd like miners to continue to collect the same fees after this change,
> we can suggest the default fee per transaction to be doubled. Half of
> every
> fee would be burned and disappear forever, effectively distributing the
> value of those bitcoins across the entire money supply. The other half
> would be collected by the miner of the block as is done today. This
> solution would mean large blocks would cost a significant number of bitcoin
> to create, even when all of the transactions are created by the miner of
> that block. For this to work, we'd need to ensure a minimum fee is paid
> for
> most of the transactions in every block, and the new transaction fee rule
> is
> in place. Then the block size limit can be removed.
>
> Raystonn
>
>
>
> ------------------------------------------------------------------------------
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists•sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>
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next prev parent reply other threads:[~2015-06-09 9:33 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-08 0:36 [Bitcoin-development] Block Size Experiment Underway Tom Harding
2015-06-08 20:07 ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit Raystonn .
[not found] ` <AD4A025F-D782-4094-9CBC-EBEF0DD04838@newcastle.ac.uk>
2015-06-08 21:14 ` Raystonn .
2015-06-08 21:33 ` Peter Todd
2015-06-08 21:40 ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the blocksize limit Raystonn .
[not found] ` <4A74E0B9-869E-448A-BFC7-7FD2F50F142F@newcastle.ac.uk>
2015-06-08 22:26 ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit Peter Todd
[not found] ` <7E7DF414-6DDB-48A6-9199-D6883209B67D@newcastle.ac.uk>
2015-06-08 21:33 ` Raystonn .
2015-06-08 21:44 ` Peter Todd
2015-06-08 22:01 ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the blocksize limit Raystonn .
2015-06-08 22:07 ` Btc Drak
2015-06-08 22:10 ` Raystonn .
2015-06-08 22:18 ` Peter Todd
2015-06-08 22:46 ` Raystonn .
2015-06-08 22:06 ` [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit Bob McElrath
2015-06-08 22:28 ` Peter Todd
2015-06-09 9:33 ` Loi Luu [this message]
2015-06-09 13:36 ` Gavin Andresen
2015-06-09 14:18 ` Tier Nolan
2015-06-09 17:52 ` Raystonn .
2015-06-09 18:25 ` Gavin Andresen
2015-06-09 19:03 ` Raystonn .
2015-06-20 3:49 ` David Vorick
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