Quote from: LoyceV on May 14, 2018, 04:11:01 PM

Quote from: Albatroz4402 on May 14, 2018, 02:31:40 PM

The private key starts with 5, so the total would be 51 characters right?

Correct.

Quote from: HCP on May 16, 2018, 05:36:13 AM

Quote from: Albatroz4402 on May 15, 2018, 06:20:32 PM

Unfortunately in my case I have no idea of the positions of the lost characters, but I keep trying, because it has been very useful for me to learn new skills and resources.

In which case, I think the search space is something like (58chars*47positions)*(58chars*47pos)*(58chars*47pos)*(58chars*47pos)... (58*47)⁴ = 5.5220891*10¹³ possible combinations Undecided

---snip---

I think your calculation is a bit off. Also we can save computation power by narrowing down search space,
the first 2 chars always start with '5H', '5J', '5K', 51-2 = 49 positions and 49-4 = 45 characters known
if exact position of 4 lost characters are known = 58^4 = 11,316,496 iterations
if exact position is unknown = 58^4 * 4-combination
= (58^4) * ( 49! / 4! (49-4)! ) = (58^4) * (46*47*2*49)
= (58^4) * 211876 = 2,397,693,906,496 iterations = 2.39 * 10¹²
do I get this right?

Quote from: HCP on May 16, 2018, 05:36:13 AM

Testing 1,000,000 combinations/second will take nearly 2 years to search all of them. (for reference, my Core i5-3570K, running Ubuntu on the Windows 10 Linux Subsystem seems to average around 200,000 combinations/second.)

are you sure we can have that computation power for combinations/second?
if compute power 200,000 combinations/second ~ 137.5 days (4.5 months)
if compute power 1,000,000 combinations/second ~ 27.75 days (1 month)
if by any chance the search space can be narrowed down even more (for e.g. assume the first 15 chars are correct)
it can cut down the number combinations and the needed time drastically