Paper 2011/479

Identity-Based (Lossy) Trapdoor Functions and Applications

Mihir Bellare, Eike Kiltz, Chris Peikert, and Brent Waters


We provide the first constructions of identity-based (injective) trapdoor functions. Furthermore, they are lossy. Constructions are given both with pairings (DLIN) and lattices (LWE). Our lossy identity-based trapdoor functions provide an automatic way to realize, in the identity-based setting, many functionalities previously known only in the public-key setting. In particular we obtain the first deterministic and efficiently searchable IBE schemes and the first hedged IBE schemes, which achieve best possible security in the face of bad randomness. Underlying our constructs is a new definition, of partial lossiness, that may be of broader interest.

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Publication info
Published elsewhere. Extended abstract in Eurocrypt 2012. This is the full version.
Identity-based encryptionpairingslatticeslossiness
Contact author(s)
mihir @ eng ucsd edu
2012-06-01: last of 3 revisions
2011-09-06: received
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      author = {Mihir Bellare and Eike Kiltz and Chris Peikert and Brent Waters},
      title = {Identity-Based (Lossy) Trapdoor Functions and Applications},
      howpublished = {Cryptology ePrint Archive, Paper 2011/479},
      year = {2011},
      note = {\url{}},
      url = {}
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