Quote from: Virtuose on April 28, 2025, 08:47:14 AM

Quote from: kTimesG on April 28, 2025, 08:34:24 AM

Quote from: Virtuose on April 28, 2025, 08:20:42 AM

My C-bit prefilter is a winner, my friend.
Convinced? ⇒ bc1qvmw6hxf7fhatxstf7vg53cd3n2a4jfa8at9wa6

I'm not. Maybe Bram is, who knows?

You still do the same amount of hashing, so there's zero saving. We don't need to derive an address. The H160 is always enough. And it's always also necessary.

You still might not find a key also.

Nice try though.

That comment misses the real win: we’re not paying the full cost of address derivation + Base58 on every candidate, only on the tiny fraction that passes the c-bit filter.

1. Linear scan does, for each x:
   - point multiplication (x·G)
   - SHA-256 → RIPEMD-160 → double-SHA-256 checksum → Base58 encoding
   - that’s dozens of heavy operations per key.

2. Prefilter does, for each x:
   - point multiplication (same)
   - only SHA-256 → RIPEMD-160 (the H160)
   - extracts c bits, compares to target filter
   - that’s one cheap H160 per key.
   - then, in ~1/2^c of cases, it does the full address derivation+Base58.

So you dramatically cut out the expensive checksum+Base58 for ~95 % or more of the keys. That is a genuine saving!

Moreover, you don’t even need to Base58-encode on the final match, you can compare the 20 byte H160 directly to your target hash160. But that only further speeds up the tiny fraction that passes the filter, it doesn’t eliminate the savings of the filter itself.

But of course we can always improve, we never need to generate the Base58 string for the final comparison, and it’s sufficient to compare hash160(pubkey(x)) directly to your HASH160_TARGET. Besides, nobody asked me for a fully fledged GPU accelerated script or anything like that. This just shows that linear is not the best. Cheesy

Genuinely curious. Did you just prompt my bounty to chatGPT or something ?
Congrats on saving time on something absolutely not necessary for the bruteforce

the linear method does not need all the extra sha256s, b58 etc…

Quote from: Virtuose on April 28, 2025, 09:54:59 AM

Um, no, I can't afford chatgpt and I only have a old desktop computer with 4 cpu ^^

ChatGPT is free to use on lower tiers which is more than enough to generate code.

Quote from: Virtuose on April 28, 2025, 09:54:59 AM

But if you could give me your linear in that case, share it and I'll show you, based on your code, that linear is crap in a box

You can simply update your own script doing something like this (Did not test it, but you should be able to understand the change required) :

Code:

# Decode address target to hex
ADDRESS_TARGET = b58decode(ADDRESS_TARGET)

# Compare with hex version of target instead of B58
def linear_scan(start: int, end: int, target: str):
   ops = 0
   for x in range(start, end+1):
   ops += 1
   if hash160_pubkey(x) == target:
   return x, ops
   return None, ops