Glacial Blocks Ahead: Watch Bitcoin's Signet Get Torture-Tested for Consensus Vulnerabilities

Bitcoin Core developers are about to show the world exactly how painful slow verification can get—and honestly, it's going to be beautiful in the worst possible way.

On Wednesday, April 7th at 10 AM EST (2 PM UTC), a handful of developers will demonstrate "attack blocks" on Bitcoin's Signet test network—blocks specifically designed to take an inordinate amount of time to verify. Anyone can participate by running a Bitcoin Core node on Signet and watching the chaos unfold in real-time. Bring popcorn. Or don't—waiting for blocks to verify might take longer than your popcorn lasts.

The demo won't showcase the worst-case scenario—that particular script and transaction structure hasn't been publicly released to avoid handing malicious actors a roadmap. Because apparently, some people would absolutely use "educational demonstration" as a starter kit for chaos. The blocks will still take orders of magnitude longer to verify than your average block. We're talking "go learn a new language" levels of waiting here.

The point? Showing users the severity of one of the four severe consensus vulnerabilities the Great Consensus Cleanup aims to fix with BIP 54. This is the crypto equivalent of your doctor showing you a smoker's lung before telling you to quit. It's uncomfortable, but maybe you'll finally listen.

Two additional demonstrations are scheduled for April 8th at 6 PM EST (10 PM UTC) and April 9th at 5 AM EST (9 AM UTC), giving global participants a chance to witness the slowness firsthand. Yes, that 5 AM slot is specifically for our degenerate international audience who treat timezones as suggestions.

The Signet blockchain sits at around 32-33 GB, so make sure your device has ample storage before spinning up a node. This isn't the time to discover your SSD is basically a 2012 laptop in disguise.

For those who want more than just staring at log files, AJ Towns contributed a patch to the "bitcoin-tui" project—a terminal-based GUI for Bitcoin Core that displays the attack blocks during the demonstration. A proper release is in the works, or you can compile it yourself:

git clone https://github.com/ajtowns/bitcoin-tui.git cd bitcoin-tui git switch 202604-bip54blocks

After compiling, ensure your bitcoind has "server=1" in your config and fire up bitcoin-tui. Look for the "Slow Blocks" tab on the right of the top bar. Finally, a use case for that terminal UI you've been pretending to understand.

The software patch used for this demo was quickly put together and not thoroughly audited—but if you're running a fresh Signet node on a machine with no funds, even the paranoid should feel fine. Worst case? Your testnet coins get stuck. Tragic. Actually, not even tragic.

Happy verifying.