On April 8th, a group of Bitcoin Core developers will demonstrate “attacking blocks” of the leading cryptocurrency on the Signet testnet. These specially designed blockchain units require significantly more time for validation.
Purpose of the Demonstration
The primary aim is to highlight the seriousness of four consensus vulnerabilities. The Great Consensus Cleanup, through BIP-54, seeks to address these issues.
This Bitcoin improvement proposal suggests a batch soft fork to clean up the consensus of the leading cryptocurrency network. A major update will address several protocol weaknesses:
- Fixing the “time warp” attack. An old vulnerability allows miners with significant hashrate to manipulate block timestamps, artificially lowering mining difficulty. BIP-54 will resolve this issue with new rules for the timestamps of the first and last blocks of each difficulty adjustment period.
- Limiting the most computationally intensive transactions. Some specially crafted operations can take a long time to verify — from several minutes to an hour on weak hardware. This increases the load on nodes and provides miners with a tool to pressure competitors. BIP-54 introduces a limit on the number of potentially executable signature operations in a single transaction. If there are too many, the transaction is deemed invalid.
- Eliminating the issue of 64-byte transactions in the Merkle tree. An operation exactly 64 bytes in size creates ambiguity in the Merkle tree: it can be interpreted as both a leaf and an internal node. This weakens the proof of inclusion and makes the Merkle root ambiguous. After BIP-54 activation, transactions exactly 64 bytes in size will be invalid.
- Eliminating the need for the outdated BIP-30 check. This is an old protection against duplicate TxIDs. After BIP-34 activation, this check is rarely needed, but historically it has to be maintained in the consensus. BIP-54 requires new Coinbase transactions to be distinct, allowing the old check to be finally removed.
The Plan
The experts do not intend to showcase the worst-case attack scenario. They will conceal script and transaction details to avoid providing additional information to potential attackers. Users will be shown blocks whose verification requires significantly more resources than usual.
The event will commence at 10:00 EST (14:00 UTC). Anyone interested can run a Bitcoin Core node on Signet (which takes about 32-33 GB) and observe the mining and processing of blocks.
Developers have also prepared a patch for visualizing suspicious units through the bitcoin-tui terminal interface (supported by developer AJ Towns). It allows real-time tracking of block processing in the Slow Blocks tab.
However, the experts emphasized that the patch was made quickly and has not undergone a full audit. For security, participants are advised to use new nodes without funds on the device.
Earlier in April, UTXOracle creator Steve Jeffress discovered that about 99% of Taproot transactions on the Bitcoin network turned out to be “dust.”