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bip-0054: rephrase Timewarp motivation

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Antoine Poinsot
2026-05-20 16:41:18 -04:00
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1 changed files with 8 additions and 10 deletions
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@@ -21,16 +21,14 @@ case block validation time, prevent Merkle tree weaknesses, and avoid duplicate
This proposal addresses a number of long-standing vulnerabilities and weaknesses in the Bitcoin
protocol. Bundling these fixes together amortizes the fixed cost of deploying a Bitcoin soft fork.
The timewarp bug permits a majority hashrate attacker to arbitrarily increase the block rate,
allowing them to steal block subsidy from future miners and increase validation costs to nodes that
have to deal with the increased average transaction rate. By strategically setting the block
timestamp, the [timewarp bug][SE timewarp] lets miners bring down the difficulty to its minimum
within 38 days of starting the attack. The existence of this bug not only significantly empowers a
51% attacker, but also makes it notably harder to reason about miners' incentives. It could indeed
be in the interest of short-sighted miners as well as short-sighted users to exploit this
vulnerability in a small enough proportion to increase the block rate without fatally hurting the
network, as the effectively increased block space would — all other things being equal — bring fee
rates down for users.
The [timewarp bug][SE timewarp] makes it possible for a majority-hashrate attacker to arbitrarily
lower mining difficulty, and therefore arbitrarily increase the block rate. In the worst case, an
attacker can bring down the difficulty to its minimum within 38 days of starting the attack. Besides
empowering a 51% attacker, the presence of this bug makes it harder to reason about miners'
incentives. Accelerating the block rate allows an attacker to steal block subsidy from future
miners and increases available block space. It may be in the interest of short-sighted users and
miners to exploit this vulnerability to materially increase the block rate without fatally hurting
the network.
Specially crafted blocks may be expensive to process, with validation times ranging from a few
minutes up to more than an hour on lower-end devices. Long block validation times are a nuisance to