A provable-security treatment of the key-wrap problem

  • Authors:
  • Phillip Rogaway;Thomas Shrimpton

  • Affiliations:
  • Dept. of Computer Science, University of California, Davis, California;Dept. of Computer Science, Portland State University, Portland, Oregon

  • Venue:
  • EUROCRYPT'06 Proceedings of the 24th annual international conference on The Theory and Applications of Cryptographic Techniques
  • Year:
  • 2006

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Abstract

We give a provable-security treatment for the key-wrap problem, providing definitions, constructions, and proofs. We suggest that key-wrap's goal is security in the sense of deterministic authenticated-encryption (DAE), a notion that we put forward. We also provide an alternative notion, a pseudorandom injection (PRI), which we prove to be equivalent. We provide a DAE construction, SIV, analyze its concrete security, develop a blockcipher-based instantiation of it, and suggest that the method makes a desirable alternative to the schemes of the X9.102 draft standard. The construction incorporates a method to turn a PRF that operates on a string into an equally efficient PRF that operates on a vector of strings, a problem of independent interest. Finally, we consider IV-based authenticated-encryption (AE) schemes that are maximally forgiving of repeated IVs, a goal we formalize as misuse-resistant AE. We show that a DAE scheme with a vector-valued header, such as SIV, directly realizes this goal.