INVESTIGATIVE DOSSIER · RESEARCHED 03 OCT 2026
BITCOIN PUZZLE #15 · 15-BIT · SOLVED

Bitcoin Puzzle #15

Solved and swept on 15 Jan 2015. The private key for this 15-bit puzzle was found inside [2^14, 2^15) and the balance was moved out.

Why puzzle #15 still matters

A solved puzzle is a benchmark. Running a cracker against it should recover the real private key, which is how you tell genuine code from a toy. Puzzle #15 needs about 2^13 key tests on average, which the in-browser engine on this site finishes in seconds.

Re-solve #15 in your browser All 256 puzzle addresses