I haven't seen updates on the m4 project in many years, and I also see that other codes have been cracked but no real progress on the m4.

What is the state of this? I continue to check out new work for it, and I see reports that the keyspace is done, in various places.

The M4 project is inactive (for now). I'll ask Stefan about any future plans.
Right now we are trying luck with M3 messages from cryptocellar.org using Stefan Krah's software and different sets of dictionaries.

Also, I'm implementing the bombe simulator. It's a slow process though, it's backend is going to be much more complicated than the one used by hillclimb algorithms.

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