Fully Adaptive Schnorr Threshold Signatures

ePrint Report: Fully Adaptive Schnorr Threshold Signatures

Elizabeth Crites, Chelsea Komlo, Mary Maller

We prove adaptive security of a simple three-round threshold Schnorr signature scheme, which we call Sparkle. The standard notion of security for threshold signatures considers a static adversary – one who must declare which parties are corrupt at the beginning of the protocol. The stronger adaptive adversary can at any time corrupt parties and learn their state. This notion is natural and practical, yet not proven to …

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