On April 8, the Bitcoin Core development team will demonstrate "attack blocks" of the first cryptocurrency on the Signet testnet. These specially designed blockchain units require significantly more time for validation.

Purpose of the Demonstration

The main goal is to highlight the seriousness of four consensus vulnerabilities. The Great Consensus Cleanup aims to address these issues through BIP-54.

This Bitcoin Improvement Proposal suggests a soft fork to clean up the consensus of the first cryptocurrency's network. A single major update will close several protocol weaknesses:

  1. Fixing the "time distortion" attack. This old vulnerability allows miners with higher hash rates 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.
  2. Limiting computationally intensive transactions. Some specially crafted operations can take a long time to verify—ranging from several minutes to an hour on weaker hardware. This increases the load on nodes and gives miners leverage over 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.
  3. Addressing the 64-byte transaction issue in the Merkle tree. A transaction exactly 64 bytes in size creates ambiguity in the Merkle tree, as it can be interpreted both as a leaf and as an internal node. This weakens the proof of inclusion for the transaction and makes the Merkle root ambiguous. After BIP-54 is activated, transactions of exactly 64 bytes will be invalid.
  4. Eliminating the outdated BIP-30 check. This was an old protection against duplicate TxIDs. After BIP-34 was activated, this check became largely unnecessary, but it has historically been retained in the consensus. BIP-54 will require new Coinbase transactions to differ, allowing the old check to be completely removed.

Event Plan

The specialists do not intend to showcase the worst-case attack scenario. They will conceal the details of the script and transactions to avoid providing additional information to potential attackers. Users will be shown blocks that require significantly more resources for verification than usual.

The event will start 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.

The developers have also prepared a patch for visualizing suspicious units through the terminal interface bitcoin-tui (supported by developer AJ Towns). This allows real-time tracking of block processing in the Slow Blocks tab.

However, the specialists emphasized that they created the patch quickly and did not conduct a full audit for it. For safety, participants are advised to use new nodes without funds on the device.

As a reminder, in April, UTXOracle creator Steve Jeffress discovered that about 99% of Taproot transactions in the Bitcoin network turned out to be "dust."