Pollard's Kangaroo · puzzle #140 interval
0 hops
tame herd, known start
wild herd, starts on the target
stored distinguished point
status: herds walking
A blind puzzle leaves you one move: pick a key, hash it, compare it to the address, repeat.
#71 hides its key somewhere in 270 candidates, so you expect to try about
590 billion billion of them before one matches.
A puzzle with an exposed public key gives you geometry instead. Kangaroo releases two herds onto
the interval, and the length of every hop is decided by wherever that kangaroo currently stands.
The moment one herd lands on a point the other already visited, both follow the identical path
forever, and the gap between where they started is the private key. The work collapses to roughly
the square root of the interval.
#135 fell exactly this way in July 2026, after the solver known as RetiredCoder spent about five
months on 200 GPUs. #140 is the next rung on the same ladder, and it is where dec0ded starts.
#71 · blind
5.9 × 1020
hashes expected. 270 range, no public key, no shortcut of any kind.
#140 · computable
9.6 × 1020
hops expected. A range 269 times larger, for 1.6× the work.