Krackpot: brute-force the Puzzle 71 wallet in your browser
Hello :)
For the longest time I wanted to build a little educational tool showing how fast a weak password gets brute-forced. That turned into a browser zip-password cracker I never released, using WebGPU to chew through passwords on the GPU. Then it sat in a folder.
Krackpot is where that WebGPU brute-forcer finally went somewhere, this time pointed at a Bitcoin Puzzle wallet. Puzzle 71 was funded on purpose in 2015 as a public challenge, holds about 7.1 BTC, and is still unsolved. The key is somewhere in a known 2^70 range, so it is pure brute force. The address is on-chain, verify it yourself.
Krackpot points your GPU at that range with WebGPU. No backend, no signup, no pool. secp256k1 and the hashing run as compute shaders in the tab. Nothing installs, nothing about your searching leaves the tab, and if your GPU ever finds the key it stays in your browser. Here is the bit I like: the same GPU that shreds a weak password in seconds can't dent a real 256-bit key. One gaming GPU is about 830,000 years to expect a hit here. A million GPUs grinding is about a year. Measured rates, not spec-sheet math. Someone still has to win.
The split is on the page before you press start: crack it, 6 BTC goes to your address, the rest goes to me. Up front it is a fee. Found out later it would be a scam.
If a key ever turns up, the transaction never goes to the public mempool. Spending a puzzle address reveals its public key, and in a range this narrow that is minutes of work to get the key back out. Puzzle 66 and 69 were both taken from their solvers that way.
So it submits privately instead, to two private mempools at once. I ran that whole path on mainnet against a key I planted in a small range and the transaction confirmed, which was the part I most wanted to see work before telling anyone about this.
Either way it shows you the key and the signed transaction first, so you are never waiting on me.
I wrote up how it works here, the WGSL crypto and the GPU watchdog fight: krackpot.io/blog/how-it-works
Please let me know what you think :)