Paper Info
Title
Public-Key Encryption with Simulation-Based Selective-Opening Security and Compact Ciphertexts.
Abstract
In a selective-opening SO attack on an encryption scheme, an adversary $$A$$A gets a number of ciphertexts with possibly related plaintexts, and can then adaptively select a subset of those ciphertexts. The selected ciphertexts are then opened for $$A$$A which means that $$A$$A gets to see the plaintexts and the corresponding encryption random coins, and $$A$$A tries to break the security of the unopened ciphertexts. Two main flavors of SO security notions exist: indistinguishability-based IND-SO and simulation-based SIM-SO ones. Whereas IND-SO security allows for simple and efficient instantiations, its usefulness in larger constructions is somewhat limited, since it is restricted to special types of plaintext distributions. On the other hand, SIM-SO security does not suffer from this restriction, but turns out to be significantly harder to achieve. In fact, all known SIM-SO secure encryption schemes either require $$\\mathbf {O} |m |$$O|m| group elements in the ciphertext to encrypt $$|m |$$|m|-bit plaintexts, or use specific algebraic properties available in the DCR setting. In this work, we present the first SIM-SO secure PKE schemes in the discrete-log setting with compact ciphertexts whose size is $$\\mathbf {O} 1$$O1 group elements plus plaintext size. The SIM-SO security of our constructions can be based on, e.g., the $$k$$k-linear assumption for any $$k$$k. Technically, our schemes extend previous IND-SO secure schemes by the property that simulated ciphertexts can be efficiently opened to arbitrary plaintexts. We do so by encrypting the plaintext in a bitwise fashion, but such that each encrypted bit leads only to a single ciphertext bit plus $$\\mathbf {O} 1$$O1 group elements that can be shared across many bit encryptions. Our approach leads to rather large public keys of $$\\mathbf {O} |m |^2$$O|m|2 group elements, but we also show how this public key size can be reduced to $$\\mathbf {O} |m |$$O|m| group elements in pairing-friendly groups.
Year
DOI
Venue
2016
10.1007/978-3-662-53644-5_6
IACR Cryptology ePrint Archive
Keywords
DocType
Volume
Public-key encryption,Selective-opening security,Lossy encryption,Matrix assumptions
Conference
2016
ISSN
Citations 
PageRank 
0302-9743
6
0.41
References 
Authors
25
3
Name
Order
Citations
PageRank
Dennis Hofheinz1154071.76
Tibor Jager242027.65
Andy Rupp319616.95