Relationship between standard model plaintext awareness and message hiding

Abstract

Recently, Bellare and Palacio succeeded in defining the plaintext awareness, which is also called PA2, in the standard model. They propose three valiants of the standard model PA2 named perfect, statistical, and computational PA2. In this paper, we study the relationship between the standard model PA2 and the property about message hiding, that is, IND-CPA. Although it seems that these two are independent notions at first glance, we show that all of the perfect, statistical, and computational PA2 in the standard model imply the IND-CPA security if the encryption function is oneway. By using this result, we also showed that "PA2 + Oneway ⇒ IND-CCA2". This result shows the "all-or-nothing" aspect of the PA2. That is, a standard model PA2 secure public-key encryption scheme either satisfies the strongest message hiding property, IND-CCA2, or does not satisfy even the weakest message hiding property, onewayness. We also showed that the computational PA2 notion is strictly stronger than the statistical one. © 2006 Springer-Verlag.