Paper 2005/032

On the Notion of Statistical Security in Simulatability Definitions

Dennis Hofheinz and Dominique Unruh


We investigate the definition of statistical security (i.e., security against unbounded adversaries) in the framework of reactive simulatability. This framework allows to formulate and analyze multi-party protocols modularly by providing a composition theorem for protocols. However, we show that the notion of statistical security, as defined by Backes, Pfitzmann and Waidner for the reactive simulatability framework, does not allow for secure composition of protocols. This in particular invalidates the proof of the composition theorem. We give evidence that the reason for the non-composability of statistical security is no artifact of the framework itself, but of the particular formulation of statistical security. Therefore, we give a modified notion of statistical security in the reactive simulatability framework. We prove that this notion allows for secure composition of protocols. As to the best of our knowledge, no formal definition of statistical security has been fixed for Canetti's universal composability framework, we believe that our observations and results can also help to avoid potential pitfalls there.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Unknown where it was published
Reactive simulatabilityuniversal composabilitystatistical securityprotocol composition
Contact author(s)
unruh @ ira uka de
2005-02-10: received
Short URL
Creative Commons Attribution


      author = {Dennis Hofheinz and Dominique Unruh},
      title = {On the Notion of Statistical Security in Simulatability Definitions},
      howpublished = {Cryptology ePrint Archive, Paper 2005/032},
      year = {2005},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.