Breaking the shared key in threshold signature schemes

By Fredrik Dahlgren

Today we are disclosing a denial-of-service vulnerability that affects the Pedersen distributed key generation (DKG) phase of a number of threshold signature scheme implementations based on the Frost, DMZ21, GG20, and GG18 protocols. The vulnerability allows a single malicious participant to surreptitiously raise the threshold required to reconstruct the shared key, which could cause signatures generated using the shared key to be invalid.

We first became aware of this vulnerability on a client engagement …

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