Robust Encryption, Revisited
The authors revisit the notions of robustness introduced by Abdalla, Bellare, and Neven (TCC 2010). One of the main motivations for the introduction of strong robustness for Public-Key Encryption (PKE) by Abdalla et al. to prevent certain types of attack on Sako's auction protocol. They show, perhaps surprisingly, that Sako's protocol is still vulnerable to attacks exploiting robustness problems in the underlying PKE scheme, even when it is instantiated with a strongly robust scheme. This demonstrates that current notions of robustness are insufficient even for one of its most natural applications. To address this and other limitations in existing notions, they introduce a series of new robustness notions for PKE and explore their relationships.