Traditionally, the term non-malleable zero-knowledge (NMZK) refers to the original definition of Dolev et al. Today, it is used loosely to also refer to simulation-soundness (SIM-SOUND) [Sahai'99], and simulation-extractability (SIM-EXT) [PR'05]. While the common perception is that SIM-EXT is the strongest of the three notions (e.g., SIM-EXT is known to imply NMZK), a formal study of the definitional relationship between these notions has never been done.
In the second part of this work, we try to correct this situation by initiating such a study. We show that in the "static" case, if an NMZK protocol is also an argument-of-knowledge, then it is in fact SIM-EXT. Furthermore, in the most strict sense of the definition, SIM-SOUND does not necessarily follow from SIM-EXT. These results are somewhat surprising because they are opposite to the common perception that SIM-EXT is the strongest of the three notions.Category / Keywords: foundations / Non-malleability, zero knowledge, commitments, black-box constructions Date: received 17 Sep 2011 Contact author: abhishek at cs ucla edu Available format(s): PDF | BibTeX Citation Version: 20110918:025745 (All versions of this report) Short URL: ia.cr/2011/513 Discussion forum: Show discussion | Start new discussion