Verifying secrets and relative secrecy

  • Authors:
  • Dennis Volpano;Geoffrey Smith

  • Affiliations:
  • Computer Science Department, Naval Postgraduate School, Monterey, California;School of Computer Science, Florida International University, Miami, Florida

  • Venue:
  • Proceedings of the 27th ACM SIGPLAN-SIGACT symposium on Principles of programming languages
  • Year:
  • 2000

Quantified Score

Hi-index 0.00

Visualization

Abstract

Systems that authenticate a user based on a shared secret (such as a password or PIN) normally allow anyone to query whether the secret is a given value. For example, an ATM machine allows one to ask whether a string is the secret PIN of a (lost or stolen) ATM card. Yet such queries are prohibited in any model whose programs satisfy an information-flow property like Noninterference. But there is complexity-based justification for allowing these queries. A type system is given that provides the access control needed to prove that no well-typed program can leak secrets in polynomial time, or even leak them with nonnegligible probability if secrets are of sufficient length and randomly chosen. However, there are well-typed deterministic programs in a synchronous concurrent model capable of leaking secrets in linear time.