Are multisigs possible in MimbleWimble?

Can someone confirm if multisig wallets/transactions are possible at all? I seem to remember some people saying adaptor sigs could accomplish this, but I cannot find any info.

Yes, of course multisig are possible with the Schnorr signatures that MW uses. All our existing transactions already use 2-of-2 multisigs between sender and receiver. And this generalizes (with some care about signing order) to n-of-n.

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Ah, yes, perhaps I should’ve been more clear. I mean M of N thresholded multisig. E.g. a single UTXO which requires 2 signatures from a group of 3 possible signers to be spent

More specifically, I want a shared ownership wallet with three people, such that two people must participate to move any funds without participation from the third person.

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Schnorr threshold signatures, such as FROST [1], are certainly possible, but the challenge is to extend them to rangeproof construction. I’m not aware of any research/publications on that.

[1] FROST — Flexible Round-Optimized Schnorr Threshold Signatures | Cryptography, Security, and Privacy (CrySP) | University of Waterloo

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Ah, very interesting… thanks for sharing. Ive never stopped to think about a threshold range proving scheme :smiley: