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The contest is fairly easy and should be easy to some of you who know how to write a python script.

I have transfered 50€ to this btc address: https://blockchain.info/nl/address/162nH1sbTZDc8WkQuFJoBaRbw17bUH8FWn

I will give out the private key in public for this address but leave out 4 characters, if you find the private key corresponding to this address you can sweep it with your btc wallet.

I am waiting for confirmations for the transfer, once confirmed i will post the private key minus 4 characters.

Why am i doing this contest? Because i am borred....

Private key: (replace asterix "*" with characters)

One confirmation, PK posted.

I wish i knew how to write a script  ???

sound good. I will express learn Python programming language haha
there are many online core to learn this language and thank you for your game event I can't solve this problem but I learn a little about it

I don't know any python myself but i think it's not that hard for people who know it.

Anyone who understands what it's about can easily do this for you.

I don't want anybody to do this "for me"... it's just a small fun contest.

I don't even need to know how the winner did it.

And the winner is....

https://www.blocktrail.com/BTC/address/3QKxo4hoDUqx2tSNE9TWDYoFsg66hE5zfT

Well, the address is from a service, so I'm not as rich as it shows there. And the 50 EUR is a great addition there, thank you very much.

I didn't use Python, I used C# and I was lucky to have the application already done (OK, for 2 missing characters, but not a big difference to make it 4), since somebody was asking for that a few months ago.
I was also lucky that the first missing letter was from the start of the alphabet, else it would have taken too long and I'd have had to leave.

Big thank you for the contest. It was quite some adrenaline :)


PS. And the merit is not because I won, it's because it was fun.

Glad you liked it  ;)

Enjoy the 50

It would be more challenging if you just told us there are 4 missing characters but left out the exact location
even not knowing only 1 exact location will increase its complexity :P and more time to find it

It's up to the one making the contest how he makes the rules and how challenging he wants it to be.
My guess is that since he was bored, he wanted something where he can see the things advancing in a rather short period of time.
Unfortunately for him, people didn't really talk much on this thread, but I think that's normal - you can't really code and chat in the same time :)

So while other options could have been more challenging, keep in mind that maybe this is what OP meant.



I made today some more tests and, while by my initial calculation, with the initial code it could have taken more than a day to get the result (in a less favorable case), my new code from today returns it in less than half an hour.
So it's easy to talk when the things have cooled down...

What was your timing.
https://i.imgur.com/FZrlz7w.jpg

55 seconds on only 25% of core i3 CPU.

Yesterday? About 1 hour!
My code needs in the least favorable case 62^4 checks if the private key matches the address. I guess that you narrowed it down to less options or the library for handling the keys/cryptography is better/faster.
Also it was not optimized for multi-processor use, not even today.

Do you have a link / rule on how to narrow down the possible letter combinations in a private key?


Edit: I see now that your 11M combinations is not that much smaller than my 14M, so I guess that I did something else wrong/slow.

My guess is that the bottleneck is checking whether the private key matches the address because it requires a lot of hashing and is somewhat calculation-heavy.

I did not narrow down anything. I am simply checking to see whether the combination I come up with is Base58 or not! And I do not use any libraries or anything, everything is coded by me that is why it is not optimized, need to find a way to use 100% CPU or even my GPU instead ::)

P.S. Make sure your code (or the library you use) does not throw exceptions! I was doing that and in a loop it will take ages to complete because exceptions are expensive.

I read some bitcoiner comments in this discussion many do not understand about python. making this discussion less interesting.
I also do not understand he he hhhhe.

please explain more details about this discussion. (python)

Thanks for the advises. I was trying to construct a wallet based on the private key. If it was incorrect, it threw exception.

The initial code was done because somebody was asking if this is possible, he was missing only 2 characters. For such quick result this was good enough. Now I see how bad actually is :)
I'll surely optimize it one of the days. And I have to use all the CPUs too. Unfortunately I have an Intel GPU so I have to stop at CPU (also I am not good enough to go for GPU programming, not yet).

How to earn more coins free

No worries. It is good to see a fellow C♯ Enthusiast.
I will probably share the code for this one of these days. I am currently super busy and in my free time I am working on my BitcoinTransactionTool. There are a lot of things to learn and fix in that. But will probably clean up this project right afterwards and post in on GitHub. It is a small (<200 lines) project.