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Bitcoin holders risk losing BTC from BIP-110 fork without replay protection

Created at 8 Aug · 2:36 AM1 source↑ Market-relevant
IN SHORT

A potential Bitcoin fork tied to BIP-110 could lead holders to lose actual BTC if they sell new coins, due to replay attacks. Developers advise avoiding transactions until early September for safety.

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Key Numbers

55%miner agreement needed for BIP-110
2.6%miner signalling as of Friday
block 961,632expected fork start block
block 965,664expected replay protection activation block

Who's Involved

Kevin Loaec
Bitcoin developer warning of replay attack risk
Bitcoin holders risk losing BTC from BIP-110 fork without replay protection

↳ Why This Matters

This potential fork and lack of replay protection pose a significant financial risk to Bitcoin holders, who could inadvertently lose their assets by attempting to profit from a perceived 'airdrop' or duplicate balance.

Key facts

  • A potential Bitcoin fork linked to BIP-110 could result in holders losing actual Bitcoin.
  • Selling coins from the forked chain may trigger a replay attack, spending BTC on the main chain.
  • The fork is expected to occur around block 961,632, potentially this weekend.
  • Replay protection is not active until block 965,664, anticipated in early September.
  • Developers advise against moving coins until replay protection is in place to prevent losses.

Bitcoin holders face the risk of losing their actual BTC if they attempt to sell coins originating from a potential fork tied to the BIP-110 proposal. This fork, expected around block 961,632 in the coming days, could create duplicate balances on two separate chains. If a holder sells the new coins, a buyer could exploit the lack of replay protection to also spend the seller's original bitcoin on the main chain.

Developers are warning that this replay attack mechanism means selling the forked coins could result in the loss of real bitcoin, not just the new, potentially worthless, coins. The BIP-110 proposal aims to restrict non-payment data in transactions for a year, requiring miner agreement. While the initial method for agreement is closed, a secondary route involves mandatory signaling starting around block 961,632. However, the actual restrictions on transaction data, which would provide replay protection, are not expected to activate until block 965,664, anticipated in early September.

Until this replay protection is in place, individuals who do not possess the technical expertise to separate the two balances are advised to avoid moving any bitcoin. Bitcoin developer Kevin Loaec highlighted this risk, suggesting that doing nothing is the safest option as unspent coins cannot be replayed. Current miner signaling for BIP-110 is low, around 2.6%, making a sustained split uncertain, but the risk of a replay attack remains if a fork does occur.

Frequently asked questions

BIP-110 is a proposal that would restrict non-payment data in Bitcoin transactions for one year, requiring miner agreement through block marking.

A replay attack occurs when a transaction signed for a forked chain can also be broadcast and executed on the main Bitcoin chain, allowing a buyer to spend the seller's real BTC.

Replay protection is not expected to be active until block 965,664, which is anticipated around the start of September.

The safest course is to avoid moving any bitcoin until replay protection is active, as unspent coins cannot be replayed.

What Happens Next

01Monitor block production for the activation of BIP-110's mandatory signaling window.
02Await the activation of replay protection around block 965,664 in early September.

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How It Developed

A potential Bitcoin fork tied to BIP-110 is expected in the coming days.
If the fork occurs, Bitcoin holders will have duplicate balances on two chains.
Selling new coins from the fork could trigger a replay attack, spending real BTC on the main chain.
Bitcoin developer Kevin Loaec warned that large holders could be targeted first.
BIP-110 requires miners to mark blocks, with a mandatory signaling window starting around block 961,632.
The proposal's restrictions on transaction data do not activate until block 965,664, around early September.
Until then, holders need to deliberately separate balances before spending to avoid replay attacks.

Sources

T1
Bitcoin holders risk losing real BTC if they sell coins from BIP-110 fork, says developerCoinDesk

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