Paper 2024/896

Dynamic-FROST: Schnorr Threshold Signatures with a Flexible Committee

Annalisa Cimatti, Roma Tre University
Francesco De Sclavis, Bank of Italy
Giuseppe Galano, Bank of Italy, University of Pisa
Sara Giammusso, Bank of Italy
Michela Iezzi, Bank of Italy
Antonio Muci, Bank of Italy
Matteo Nardelli, Bank of Italy
Marco Pedicini, Roma Tre University

Threshold signatures enable any subgroup of predefined cardinality $t$ out of a committee of $n$ participants to generate a valid, aggregated signature. Although several $(t,n)$-threshold signature schemes exist, most of them assume that the threshold $t$ and the set of participants do not change over time. Practical applications of threshold signatures might benefit from the possibility of updating the threshold or the committee of participants. Examples of such applications are consensus algorithms and blockchain wallets. In this paper, we present Dynamic-FROST (D-FROST, for short) that combines FROST, a Schnorr threshold signature scheme, with CHURP, a dynamic proactive secret sharing scheme. The resulting protocol is the first Schnorr threshold signature scheme that accommodates changes in both the committee and the threshold value without relying on a trusted third party. Besides detailing the protocol, we present a proof of its security: as the original signing scheme, D-FROST preserves the property of Existential Unforgeability under Chosen-Message Attack.

Available format(s)
Cryptographic protocols
Publication info
Proactive secret sharingThreshold signaturesDecentralizationFROSTCHURP
Contact author(s)
ann cimatti @ stud uniroma3 it
francesco desclavis @ bancaditalia it
giuseppe galano2 @ bancaditalia it
sara giammusso @ bancaditalia it
michela iezzi @ bancaditalia it
antonio muci @ bancaditalia it
matteo nardelli @ bancaditalia it
marco pedicini @ uniroma3 it
2024-06-06: approved
2024-06-05: received
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      author = {Annalisa Cimatti and Francesco De Sclavis and Giuseppe Galano and Sara Giammusso and Michela Iezzi and Antonio Muci and Matteo Nardelli and Marco Pedicini},
      title = {Dynamic-{FROST}: Schnorr Threshold Signatures with a Flexible Committee},
      howpublished = {Cryptology ePrint Archive, Paper 2024/896},
      year = {2024},
      note = {\url{}},
      url = {}
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