Waterloo Cybersecurity and Privacy Institute • UC Non-Interactive, Proactive, Threshold ECDSA with Identifiable AbortsExport this event to calendar

Monday, December 7, 2020 — 10:00 AM EST

Please note: This Waterloo CPI seminar will be giving online.

Nikolaos Makriyannis, Cryptography researcher
Fireblocks

Building on the Gennaro & Goldfeder and Lindell & Nof protocols (CCS '18), we present two threshold ECDSA protocols, for any number of signatories and any threshold, that improve as follows over the state of the art: 

  • For both protocols, only the last round requires knowledge of the message, and the other rounds can take place in a preprocessing stage, lending to a non-interactive threshold ECDSA protocol. 
  • Both protocols withstand adaptive corruption of signatories. Furthermore, they include a periodic refresh mechanism and offer full proactive security.
  • Both protocols realize an ideal threshold signature functionality within the UC framework, in the global random oracle model, assuming Strong RSA, DDH, semantic security of the Paillier encryption, and a somewhat enhanced variant of existential unforgeability of ECDSA.
  • Both protocols achieve accountability by identifying corrupted parties in case of failure to generate a valid signature. 

The two protocols are distinguished by the round-complexity and the identification process for detecting cheating parties. Namely:

  • For the first protocol, signature generation takes only 4 rounds (down from the current state of the art of 8 rounds), but the identification process requires computation and communication that is quadratic in the number of parties. 
  • For the second protocol, the identification process requires computation and communication that is only linear in the number of parties, but signature generation takes 7 rounds.

These properties (low latency, compatibility with cold-wallet architectures, proactive security, identifiable abort and composable security) make the two protocols ideal for threshold wallets for ECDSA-based cryptocurrencies.


Bio: I received my BSc and MSc in Mathematics from Imperial College and EPFL, respectively. I obtained my Ph.D. from Universitat Pompeu Fabra under Prof. Vanesa Daza. The topic of my PhD thesis was Fairness in Secure Multi-Party Computation. In recent years I was a postdoc at Tel-Aviv University (hosted by Prof. Iftach Haitner) and at Technion (hosted by Prof. Yuval Ishai). I am currently a cryptography researcher at Fireblocks, a digital asset security platform.

I have a broad interest in cryptography with a particular focus on MPC.


To join this Waterloo Cybersecurity and Privacy Institute seminar on Zoom, please go to https://us02web.zoom.us/j/88180114806?pwd=YXVFd0gwWGtkTWtzaVBid1dkQ2lVZz09.

Meeting ID: 881 8011 4806 
Passcode: 748175

Location 
Online seminar
200 University Avenue West

Waterloo, ON N2L 3G1
Canada

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