I am really intrigued by FROST. It is a way of using Schnorr signatures (added in the Taproot upgrade) to do a bunch of pretty cool stuff with multisigs.

If you make a private key and use Shamir Secret Shares to split it into pieces, you still have the problem that the key must be assembled in one piece before you sign.

You can fix this by making a multisig and using a PSBT to collect signatures from the transaction so that you never need to bring all the keys together in one place. But now you have a big transaction that is obviously a multisig and everyone can see that about it on the chain.

Enter FROST! FROST allows users to generate a private key using a number of pubkeys, but in such a way that the private key never exists in any one place.

For example, three users (or keys) can work together to create a public key and then in process that takes a couple rounds of communication, can generate a public key that, when signed by a threshold of these keys, looks like a normal single sig spend.

The bigger news in the linked announcement at the head of this post is that the good people at Blockchain Commons have been working on making FROST work with BDK. This is pretty huge because BDK is an easy framework on which to build Bitcoin wallets.

Blockchain Commons larger goal is to create a tool similar to their Learning Bitcoin from the Command Line. This is all very good, because, as a huge fan of multisig, I've been worried about multisig's onchain footprint (both fee-wise and privacy-wise) and I've been tracking with some excitement the possibility of widespread FROST usage.