Welcome!
To use the personalized features of this site, please log in or register.
If you have forgotten your username or password, we can help.
My Menu
Saved Items

Assumptions Related to Discrete Logarithms: Why Subtleties Make a Real Difference

Ahmad-Reza SadeghiContact Information and Michael SteinerContact Information

(5)  Fachrichtung Informatik, Universität des Saarlandes, D-66123 Saarbrücken, Germany
Abstract
The security of many cryptographic constructions relies on assumptions related to Discrete Logarithms (DL), e.g., the Diffie-Hellman, Square Exponent, Inverse Exponent or Representation Problem assumptions. In the concrete formalizations of these assumptions one has some degrees of freedom offered by parameters such as computational model, the problem type (computational, decisional) or success probability of adversary. However, these parameters and their impact are often not properly considered or are simply overlooked in the existing literature. In this paper we identify parameters relevant to cryptographic applications and describe a formal framework for defining DL-related assumptions. This enables us to precisely and systematically classify these assumptions.
In particular, we identify a parameter, termed granularity, which describes the underlying probability space in an assumption. Varying granularity we discover the following surprising result:We prove that two DL-related assumptions can be reduced to each other for medium granularity but we also show that they are provably not reducible with generic algorithms for high granularity. Further we show that reductions for medium granularity can achieve much better concrete security than equivalent high-granularity reductions.

Keywords  Complexity Theory - Cryptographic Assumptions - Generic Algorithms - Discrete Logarithms - Diffie-Hellman - Square Exponent - Inverse Exponent


Contact Information Ahmad-Reza Sadeghi
Email: sadeghi@cs.uni-sb.de

Contact Information Michael Steiner
Email: steiner@cs.uni-sb.de
Fulltext Preview (Small, Large)
Image of the first page of the fulltext

References secured to subscribers.



Export this chapter
Export this chapter as RIS | Text
 
Remote Address: 38.107.191.107 • Server: MPWEB25
HTTP User Agent: CCBot/1.0 (+http://www.commoncrawl.org/bot.html)