Harry W. H. Wong (The Chinese University of Hong Kong), Jack P. K. Ma (The Chinese University of Hong Kong), Sherman S. M. Chow (The Chinese University of Hong Kong)

Threshold signatures, notably ECDSA, are fundamental for securing decentralized applications. Their non-linear structure poses challenges in distributed signing, often tackled by pairwise multiplicative-to-additive share conversion, leading to O(n) communication and O(n2) verification costs for each of n signers. Moreover, most schemes lack robustness, necessitating a complete restart upon fault. A pioneering work by Wong et al. (NDSS '23) still requires rolling back to the preceding round to resume signing after another round to convince all other signers.

We revisit secure multiparty computation from threshold linearly homomorphic encryption (LHE). Realizing its public verifiability and fault recovery, we encompass two technical contributions to Castagnos–Laguillaumie LHE (CT-RSA '15): a 2-round robust distributed key generation (DKG) protocol in the dishonest majority setting and an accompanying zero-knowledge proof allowing extraction in an unknown-order group. We extend the DKG with dual-code-based verification (ACNS '17), upgrading its O(tn2)-cost private verifiability to an O(n2) public one.

Built on our DKG, we present the first threshold ECDSA protocol with O(1) communication and O(n) verification per-party costs while matching the lowest round complexity of nonrobust schemes (CCS '20). Empirically, we halve the computation and communication costs of the signing phase compared to state-of-the-art robust threshold ECDSA (NDSS '23). We also illustrate the versatility of our techniques with an improved threshold extension (IEEE S&P '23) of BBS+ signatures (IEEE Syst. J. '13).

View More Papers

QUACK: Hindering Deserialization Attacks via Static Duck Typing

Yaniv David (Columbia University), Neophytos Christou (Brown University), Andreas D. Kellas (Columbia University), Vasileios P. Kemerlis (Brown University), Junfeng Yang (Columbia University)

Read More

Why People Still Fall for Phishing Emails: An Empirical...

Asangi Jayatilaka (Centre for Research on Engineering Software Technologies (CREST), The University of Adelaide, School of Computing Technologies, RMIT University), Nalin Asanka Gamagedara Arachchilage (School of Computer Science, The University of Auckland), M. Ali Babar (Centre for Research on Engineering Software Technologies (CREST), The University of Adelaide)

Read More

FirmLine: a Generic Pipeline for Large-Scale Analysis of Non-Linux...

Alexander Balgavy (Independent), Marius Muench (University of Birmingham)

Read More