*18:17*[Pub][ePrint] On the Joint Security of Signature and Encryption Schemes under Randomness Reuse: Efficiency and Security Amplification, by Afonso Arriaga and Manuel Barbosa and Pooya Farshim

We extend the work of Bellare, Boldyreva and Staddon on the systematic analysis of randomness reuse to construct multi-recipient

encryption schemes to the case where randomness is reused across different cryptographic primitives. We find that through the additional binding introduced through randomness reuse, one can actually obtain a security amplification with respect to the standard black-box compositions, and achieve a stronger level of security. We introduce stronger notions of security for encryption and signatures,

where challenge messages can depend in a restricted way on the random coins used in encryption, and show that two variants of the KEM/DEM paradigm give rise to encryption schemes that meet this enhanced notion of security. We obtain a very efficient signcryption scheme that is

secure against insider attackers without random oracles.