Paper 2016/121
Tightly-Secure Pseudorandom Functions via Work Factor Partitioning
Tibor Jager
Abstract
We introduce a new technique for tight security proofs called work factor partitioning. Using this technique in a modified version of the framework of Döttling and Schröder (CRYPTO 2015), we obtain the first generic construction of tightly-secure pseudorandom functions (PRFs) from PRFs with small domain. By instantiating the small-domain PRFs with the Naor-Reingold function (FOCS 1997) or its generalization by Lewko and Waters (ACM CCS 2009), this yields the first fully-secure PRFs whose black-box security proof loses a factor of only O(log^2 \lambda), where \lambda is the security parameter. Interestingly, our variant of the Naor-Reingold construction can be seen as a standard Naor-Reingold PRF (whose security proof has a loss of \Theta(\lambda)), where a special encoding is applied to the input before it is processed. The tightness gain comes almost for free: the encoding is very efficiently computable and increases the length of the input only by a constant factor smaller than 2.
Metadata
- Available format(s)
- -- withdrawn --
- Category
- Foundations
- Publication info
- Preprint. MINOR revision.
- Keywords
- Tight securitypseudorandom functionsprovable security
- Contact author(s)
- tibor jager @ rub de
- History
- 2016-10-03: withdrawn
- 2016-02-14: received
- See all versions
- Short URL
- https://ia.cr/2016/121
- License
-
CC BY