INVESTIGATIVE DOSSIER · RESEARCHED 03 OCT 2026
BITCOIN PUZZLE #40 · 40-BIT · SOLVED

Bitcoin Puzzle #40

Solved and swept on 30 Jan 2015. The private key for this 40-bit puzzle was found inside [2^39, 2^40) and the balance was moved out.

Why puzzle #40 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 #40 needs about 2^38 key tests on average.

Re-solve #40 in your browser All 256 puzzle addresses