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From: Tim Ruffing <crypto@timruffing.de>
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Date: Mon, 24 Feb 2020 12:16:38 +0100
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Subject: Re: [bitcoin-dev] Composable MuSig
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On Sun, 2020-02-23 at 02:27 -0500, Erik Aronesty via bitcoin-dev wrote:
> > Thus, two-phase MuSig is potentially unsafe.
> > https://eprint.iacr.org/2018/417.pdf describes the argument.
> 
> One solution is to add a signature timeout to the message (say a
> block height) .  
> 
> A participant refuses to sign if that time is too far in the future,
> or is at all in the past, or if a message M is the same as any
> previous message within that time window.
> 
> Seems to resolve the attacks on 2 round musig.

I don't understand this. Can you elaborate?

Best,
Tim