Paper 2010/117

Cryptographic Agility and its Relation to Circular Encryption

Tolga Acar, Mira Belenkiy, Mihir Bellare, and David Cash


We initiate a provable-security treatment of cryptographic \emph{agility}. A primitive (for example PRFs, authenticated encryption schemes or digital signatures) is agile when multiple, individually secure schemes can securely share the same key. We provide a surprising connection between two seemingly unrelated but challenging questions. The first, new to this paper, is whether wPRFs (weak-PRFs) are agile. The second, already posed several times in the literature, is whether every secure (IND-R) encryption scheme is secure when encrypting cycles. We resolve the second question in the negative and thereby the first as well. We go on to provide a comprehensive treatment of agility, with definitions for various different primitives. We explain the practical motivations for agility. We provide foundational results that show to what extent it is achievable and practical constructions to achieve it to the best extent possible. On the theoretical side our work uncovers new notions and relations and settles stated open questions, and on the practical side it serves to guide developers.

Available format(s)
Publication info
Published elsewhere. Preliminary version in EUROCRYPT 2010. This is the full version.
Circular encryption
Contact author(s)
cdc @ gatech edu
2010-03-05: received
Short URL
Creative Commons Attribution


      author = {Tolga Acar and Mira Belenkiy and Mihir Bellare and David Cash},
      title = {Cryptographic Agility and its Relation to Circular Encryption},
      howpublished = {Cryptology ePrint Archive, Paper 2010/117},
      year = {2010},
      note = {\url{}},
      url = {}
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