Paper Info
Title
Security of encryption schemes in weakened random oracle models
Abstract
Liskov proposed several weakened versions of the random oracle model, called weakened random oracle models (WROMs), to capture the vulnerability of ideal compression functions, which are expected to have the standard security of hash functions, i.e., collision resistance, second-preimage resistance, and one-wayness properties. The WROMs offer additional oracles to break such properties of the random oracle. In this paper, we investigate whether public-key encryption schemes in the random oracle model essentially require the standard security of hash functions by the WROMs. In particular, we deal with four WROMs associated with the standard security of hash functions; the standard, collision tractable, second-preimage tractable, first-preimage tractable ones (ROM, CT-ROM, SPT-ROM, and FPT-ROM, respectively), done by Numayama et al. for digital signature schemes in the WROMs. We obtain the following results: (1) The OAEP is secure in all the four models. (2) The encryption schemes obtained by the Fujisaki-Okamoto conversion (FO) are secure in the SPT-ROM. However, some encryption schemes with FO are insecure in the FPT-ROM. (3) We consider two artificial variants wFO and dFO of FO for separation of the WROMs in the context of encryption schemes. The encryption schemes with wFO (dFO, respectively) are secure in the CT-ROM (ROM, respectively). However, some encryption schemes obtained by wFO (dFO, respectively) are insecure in the SPT-ROM (CT-ROM, respectively). These results imply that standard encryption schemes such as the OAEP and FO-based one do not always require the standard security of hash functions. Moreover, in order to make our security proofs complete, we construct an efficient sampling algorithm for the binomial distribution with exponentially large parameters, which was left open in Numayama et al.’s paper.
Year
DOI
Venue
2010
10.1007/978-3-642-13013-7_24
IACR Cryptology ePrint Archive
Keywords
DocType
Volume
hash function,weakened random oracle model,security proof,standard security,random oracle model,standard encryption scheme,additional oracle,oaep,public-key encryption schemes,artificial variants wfo,fujisaki- okamoto conversion.,encryption scheme,weakened random oracle models,random oracle,public-key encryption scheme,public key encryption,binomial distribution
Conference
2010
ISBN
Citations 
PageRank 
3-642-13012-7
4
0.38
References 
Authors
30
4
Name
Order
Citations
PageRank
Akinori Kawachi118520.66
Akira Numayama2171.61
Keisuke Tanaka327819.04
Keita Xagawa425820.51