Update 4: There's a solve!!! Congrats to @killa (https://x.com/killa) who actually posted the last 3 characters of the private key in this very thread a few hours ago.
Turns out exporting a well-formed bitcoin wallet key is hard. I put a wallet-branch WIF on the server, rather than the WIF for the funded address inside that wallet.
Server logs support this being the first (and indeed only) successful execution of the `print-flag` binary with exfiltration and the person who contacted me definitely knows the value of the WIF key on the server so I'm going to evalute this like a solve. I'm in touch with the person who has the flag now and will transfer the wallet to them shortly.
Transfer made. Next steps will be an operator writeup - thanks for keeping this weekend exciting everyone. Since I now own the stealmybitcoin.com domain (can't believe it wasn't taken), I'm sure some new challenge will end up there eventually ;)
Turns out exporting a well-formed bitcoin wallet key is hard. I put a wallet-branch WIF on the server, rather than the WIF for the funded address inside that wallet.
Server logs support this being the first (and indeed only) successful execution of the `print-flag` binary with exfiltration and the person who contacted me definitely knows the value of the WIF key on the server so I'm going to evalute this like a solve. I'm in touch with the person who has the flag now and will transfer the wallet to them shortly.
Transfer made. Next steps will be an operator writeup - thanks for keeping this weekend exciting everyone. Since I now own the stealmybitcoin.com domain (can't believe it wasn't taken), I'm sure some new challenge will end up there eventually ;)
Update 4.5: Challenge source (mostly courtesy of Codex...) posted here: https://github.com/pavja2/smbc-source-oct-2026