Yes and no. I created one bruteforce tool which could do 100,000 tries in one second which was being used for finding brain wallets only.

For this challenge, I created another brute force tool which did following:
1. Split the guesses in many batches
2. Assemble the first guess in the batch as a base58 string
3. Then do a base58_decode which outputs a 37 byte binary
4. Take byte #1 to #32 (counting from #0) and load it into the EC library (yes, you can ignore the checksum here)
5. Do an EC point multiplication p=G*k where p=public key, G=base point and k=your first guess
6. If ripemd160(sha256(p)) matches target, alert and stop
7. Do an EC point addition p=p+G and goto 6. until 58ⁿ/2³² repetitions has been made. n is the number of characters missing at the end
8. Open a new batch and goto 2

This gave me the boost to try 500,000 valid keys in one second.
My computer found the key in under 4 hours instead of cracking for days because I told the bruteforcer to try a limited character set first. It was:

• Alphabet 6Fabcdefghijkmnopqrstuvwxyz for puzzle #9, char #1,2,4,5
• Alphabet 6abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ for puzzle #9, char #3

Puzzle #10 was auto-solved by the ECDSA point addition loop.


I would be happy to hear from the anonymous cracker what his/her approach was because I'm curious.