How to safely withdraw BTC from puzzle wallets (71 included)

Hey everyone, since I’ve seen more interest lately around the puzzles and some people getting sniped, I thought I’d post a quick guide on how to do it right. Especially since puzzle 71 is very close to being found and it has over 7 BTC in it.

This method works for any puzzle where the private key is in a low range and you're able to recover it. If you just found the key and you're planning to import it in Electrum and click send... stop right now and read.

Why you shouldn't use the mempool

Once you broadcast a transaction to the public mempool (even with a high fee), the pubKey becomes visible. That means anyone monitoring the network can instantly start brute-forcing the private key and if the range is small (like puzzle 71), they'll find it in seconds. Even if you broadcast first, someone can RBF you with a higher fee and steal it.

It already happened with multiple puzzles. Some bots are running 24/7 and replacing transactions 50+ times until they win.

Correct way to withdraw

1. Generate a secure BTC address

Don’t send funds to an old or reused address. Use a new address from a wallet you control. Sparrow wallet is good, Electrum works too, or hardware wallet. Segwit is fine. Save the seed and verify it works.

2. Craft the transaction offline

Import the puzzle private key into an offline wallet or use command-line tools (bitcoin-tx or Sparrow in offline mode). Build a transaction that sends the funds to your new BTC address.

Set a high fee. I’d recommend something like 30k to 100k sats depending on size. If the TX is 300 vbytes, go with 300 sat/vB or more. Don’t cheap out on this, it’s less than $50 to secure over $700k worth of BTC.

Export the signed raw transaction as HEX. Do not broadcast it yet.

3. Use a miner relay (not public broadcast)

Now go to: https://slipstream.mara.com/

This is a private relay to the Marathon mining pool. Paste your signed TX hex and submit it. That way, your transaction goes directly to the miner and isn’t seen by the public mempool or sniping bots.

Once it’s mined, the BTC will be in your address. At that point, it’s too late for anyone to do anything the UTXO is already spent.

What if I don’t use slipstream?

Then your transaction will show up in the mempool, bots will see it, and if you’re not using RBF defense or an aggressive strategy, they can and will steal it. You’ll see your TX dropped and someone else’s version with a higher fee getting confirmed.

If you’re not 100% sure how to use slipstream or build a raw TX, ask before you risk it.

Puzzle 71 warning

We’re almost there. Someone will solve 71 soon, maybe already has. If you’re the one who gets the key, please don’t lose the funds by broadcasting it naively. Follow the steps above and you’ll be fine.

Happy hunting and stay safe.