Hardening Signature Schemes via Derive-then-Derandomize: Stronger Security Proofs for EdDSA

ePrint Report: Hardening Signature Schemes via Derive-then-Derandomize: Stronger Security Proofs for EdDSA

Mihir Bellare, Hannah Davis, Zijing Di

We consider a transform, called Derive-then-Derandomize, that hardens a given signature scheme against randomness failure and implementation error. We prove that it works. We then give a general lemma showing indifferentiability of Shrink-MD, a class of constructions that apply a shrinking output transform to an MD-style hash function. Armed with these tools, we give new proofs for the widely standardized and used …

called class eprint report error function general hardening hash hash function prove randomness report security signature tools