You should definitively use hashcat[0]. It's the fastest hashing tool at the moment, and it supports both PBKDF2-HMAC-SHA256 and SCRYPT for Ethereum wallets since the last update.

It can test 588 passwords per second on my modest GPU. I guess that's a lot better than a basic Python script.

You should also have a look at probable wordlists[1], which contains a lot of passwords sorted by their popularity. It could significantly speedup the research, as long as your password has already leaked elsewhere.

[0] https://hashcat.net/hashcat/

[1] https://github.com/berzerk0/Probable-Wordlists

The password definitely hasn't leaked as it is a one time password I created based on a somewhat complex scheme, but switching to hashcat (as also pointed outby flipp3r) seems to be the best next step.

The encryption actually is KECCAK-256, not SHA-3. However, if you are using a library built for Ethereum it'll be called SHA-3.

When Ethereum was being developed, the spec for SHA-3 wasn't finished or something: https://ethereum.stackexchange.com/questions/550/which-crypt...

It sounds like you have it under control but I typically point people to Dave @ https://walletrecoveryservices.com/ for the less tech-savvy. He's pretty good. You can look at his site for what he can and can't crack. I know he's super super busy but it never hurts to give him a shout and ask him if he has any pro-tips or open-source code somewhere. A ping from someone who has a basic understanding of encryption might be refreshing.

Here are a random assortment of links I have saved regarding recovering presales:

https://www.reddit.com/r/ethereum/comments/46887p/tips_for_r...

https://forum.ethereum.org/discussion/3045/request-post-pass...

https://www.reddit.com/r/ethereum/comments/3g6aw0/i_lost_my_...

Python? There's tools for this, like oclHashcat/cudaHashcat

It's pretty easy to speed up the process by using multi threaded gpu code.