Still far away for puzzle #64 or puzzle #120
from last Kangaroo record
#105 Solved 23/09/2019
#110 Solved 30/05/2020
#115 Solved 16/06/2020
For now 17/11/2021
over pass a year not yet found any key on puzzle list
from history may be need new one method to solve puzzle
like from bitcrack and change to kangaroo and What next?
High powerful GPU not answer (but GPU is very very useful) but need some algorithm to solve it
There will be nothing "next", taht's the whole point of the challenge transaction, to find the exact limits for collective mass attack on Bitcoin keys. after #64 is solved, it will take many years before #66 is solved, and do not hold your breath for #67...
#120 is much less important, even i there were some big advancments in kangaroo, and #120, #125, etc are solved quickly, everyone knows the coins should not be kept on reused BTC addresses with known public keys.