YACL Talk | Adam O'Neill (UMass Amherst) - Schnorr Signatures are Tightly Secure in the ROM under a Non-Interactive Assumption

[Aviv Yaish]

Join us for our next YACL talk!

When: Friday (Feb 7), 11:00-noon

Where: AKW200, Arthur K. Watson Hall, 51 Prospect St, New Haven, CT 06511, US

Speaker: Adam O'Neill (UMass Amherst)

Title: Schnorr Signatures are Tightly Secure in the ROM under a Non-Interactive Assumption

Abstract:
We show that the widely-used Schnorr signature scheme meets existential unforgeability under chosen-message attack (EUF-CMA) in the random oracle model (ROM) if the circular discrete-logarithm (CDL) assumption, a new, non-interactive, and falsifiable variant of DL we introduce, holds in the underlying group. Notably, our reduction is *tight*, meaning the constructed adversary against CDL has essentially the same running time and success probability as the assumed forger. Tightness is essential for justifying the key length used in practice. To our knowledge, we are the first to exhibit such a reduction to even a non-interactive assumption. We justify CDL by showing it is as hard as DL in two carefully chosen idealized models, which idealize different aspects of the assumption.

Links:
- https://eprint.iacr.org/2024/1528

Bio:
Adam O’Neill is an Assistant Professor in the Manning College of Information and Computer Sciences at the University of Massachusetts, Amherst. Previously, he was an Assistant Professor of Computer Science at Georgetown University. He received his Ph.D. in Computer Science at the Georgia Institute of Technology and held postdoctoral appointments at the University of Texas at Austin and Boston University. His doctoral work was recognized with the CRYPTO 2022 Test-of-Time Award.

Livestream:
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More:
For additional details about the talk and our seminar, see our website: https://sites.google.com/view/yacl

[Aviv Yaish]

If you missed Adam's great talk, you can still watch it here: https://youtu.be/WeRQci1XLto