Federated distributed key generation
Stanisław Barański, Julian Szymański · Future Generation Computer Systems · 2025
Distributed Key Generation (DKG) underpins threshold cryptography across many domains: decentralized custody and wallets, validator/committee key ceremonies, cross-chain bridges, threshold signatures, secure multiparty computation, and internet voting. Classical ( t, n )-DKG assumes a fixed set of n parties and a global threshold t , and effectively requires full, timely participation; when actual participation or availability deviates, setups abort or must be return a severe problem in open or ad-hoc, time-critical settings, especially when n is large and node availability is unpredictable.” We introduce Federated Distributed Key Generation (FDKG) , inspired by Federated Byzantine Agreement, that makes participation optional and trust heterogeneous . Each participant selects a personal guardian set G i of size k and a local threshold t ; its partial secret can later be reconstructed either by itself or by any t of its guardians. FDKG generalizes PVSS-based DKG and completes both generation and reconstruction in a single broadcast round each, with total communication Θ( n k ) and (in the worst case) O ( n 2 ) for reconstruction. Our security analysis shows that: (i) Generation achieves correctness, privacy, and robustness under standard PVSS-based DKG assumptions; and (ii) Reconstruction provides liveness and privacy characterized by the guardian-set topology { G i } . Liveness holds provided that, for every participant i , the adversary does not control i together with at least k − t + 1 of its guardians. Conversely, reconstruction privacy holds unless the corrupted set itself is reconstruction-capable. In a scenario with n = 100 potential parties ( | D | = 50 , k = 40 , 80 % retention for tallying), FDKG distribution broadcasts ≈ 336 kB and reconstruction ≈ 525 kB. Client-side Groth16 proving per participant is ≈ 5 s for distribution, and 0.6-29.6s for reconstruction depending on the number of revealed shares.