Questions about Bitcrack usage

I just started using Bitcrack to try and crack Address #66 for 6.6btc. Just a quick question, the command from the BTC puzzle challenge is it for random searching? It goes like this: "xxBitCrack.exe keyspace 20000000000000000:3ffffffffffffffff -c 13zb1hQbWVsc2S7ZTZnP2G4undNNpdh5so". I see a lot of people are doing pools, but I'm trying to go solo in random mode. So, am I actually doing random searches with this command? I tried looking for answers on GitHub but didn’t find anything. What if Bitcrack doesn’t support random mode?

Nah man, it's actually sequential based on the stride you set, which defaults to counting by 1. AFAIK, there are some user forks out there that do random searches, but I can't really vouch for any since they’re mostly closed-source. If you're keen, check GitHub for those forks.

Looking for a random mode, I found some weird stuff. Results seem strange, like I get exact hits at the edge of a range. Like, if I'm searching in a range of 2*10, results pop up right after making 2**10 attempts. Just trying to downgrade this 0x323e8459183029cd09f67ca6273f67e67 from 130 bit to 120 bit. Found this combo: 0x9459183029cd09f6bca6273f67e67, 0x323defffffffffffffffc000000000000. Positive results: 133, Negative: 135344, total is 135477. So, that’s one good for every 1000 false hits.

If you're looking for a random mode, check out Keyhunt-CUDA or Rotor-CUDA. They have the "rkey" option (-r), which picks random starting points in the range. It then increases from there sequentially, changing the random starting points each time you reach the threshold you set. For example, if you put "-r 10", it'll pick new random starting points every 10 billion keys checked.