Results 1  10
of
132
Trapdoors for Hard Lattices and New Cryptographic Constructions
, 2007
"... We show how to construct a variety of “trapdoor ” cryptographic tools assuming the worstcase hardness of standard lattice problems (such as approximating the shortest nonzero vector to within small factors). The applications include trapdoor functions with preimage sampling, simple and efficient “ha ..."
Abstract

Cited by 186 (25 self)
 Add to MetaCart
We show how to construct a variety of “trapdoor ” cryptographic tools assuming the worstcase hardness of standard lattice problems (such as approximating the shortest nonzero vector to within small factors). The applications include trapdoor functions with preimage sampling, simple and efficient “hashandsign ” digital signature schemes, universally composable oblivious transfer, and identitybased encryption. A core technical component of our constructions is an efficient algorithm that, given a basis of an arbitrary lattice, samples lattice points from a Gaussianlike probability distribution whose standard deviation is essentially the length of the longest vector in the basis. In particular, the crucial security property is that the output distribution of the algorithm is oblivious to the particular geometry of the given basis. ∗ Supported by the Herbert Kunzel Stanford Graduate Fellowship. † This material is based upon work supported by the National Science Foundation under Grants CNS0716786 and CNS0749931. Any opinions, findings, and conclusions or recommedations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. ‡ The majority of this work was performed while at SRI International. 1 1
Searchable symmetric encryption: improved definitions and efficient constructions
 Proceedings of the 13th ACM conference on Computer and communications security, CCS ’06, ACM
, 2006
"... Searchable symmetric encryption (SSE) allows a party to outsource the storage of his data to another party in a private manner, while maintaining the ability to selectively search over it. This problem has been the focus of active research and several security definitions and constructions have been ..."
Abstract

Cited by 171 (6 self)
 Add to MetaCart
(Show Context)
Searchable symmetric encryption (SSE) allows a party to outsource the storage of his data to another party in a private manner, while maintaining the ability to selectively search over it. This problem has been the focus of active research and several security definitions and constructions have been proposed. In this paper we begin by reviewing existing notions of security and propose new and stronger security definitions. We then present two constructions that we show secure under our new definitions. Interestingly, in addition to satisfying stronger security guarantees, our constructions are more efficient than all previous constructions. Further, prior work on SSE only considered the setting where only the owner of the data is capable of submitting search queries. We consider the natural extension where an arbitrary group of parties other than the owner can submit search queries. We formally define SSE in this multiuser setting, and present an efficient construction. 1
Conjunctive, subset, and range queries on encrypted data
, 2007
"... We construct publickey systems that support comparison queries (x ≥ a) on encrypted data as well as more general queries such as subset queries (x ∈ S). Furthermore, these systems support arbitrary conjunctive queries (P1 ∧ · · · ∧ Pℓ) without leaking information on individual conjuncts. We p ..."
Abstract

Cited by 169 (20 self)
 Add to MetaCart
We construct publickey systems that support comparison queries (x ≥ a) on encrypted data as well as more general queries such as subset queries (x ∈ S). Furthermore, these systems support arbitrary conjunctive queries (P1 ∧ · · · ∧ Pℓ) without leaking information on individual conjuncts. We present a general framework for constructing and analyzing publickey systems supporting queries on encrypted data.
Predicate Encryption Supporting Disjunctions, Polynomial Equations, and Inner Products
"... Abstract. Predicate encryption is a new paradigm generalizing, among other things, identitybased encryption. In a predicate encryption scheme, secret keys correspond to predicates and ciphertexts are associated with attributes; the secret key SKf corresponding to a predicate f can be used to decryp ..."
Abstract

Cited by 168 (23 self)
 Add to MetaCart
Abstract. Predicate encryption is a new paradigm generalizing, among other things, identitybased encryption. In a predicate encryption scheme, secret keys correspond to predicates and ciphertexts are associated with attributes; the secret key SKf corresponding to a predicate f can be used to decrypt a ciphertext associated with attribute I if and only if f(I) = 1. Constructions of such schemes are currently known for relatively few classes of predicates. We construct such a scheme for predicates corresponding to the evaluation of inner products over ZN (for some large integer N). This, in turn, enables constructions in which predicates correspond to the evaluation of disjunctions, polynomials, CNF/DNF formulae, or threshold predicates (among others). Besides serving as a significant step forward in the theory of predicate encryption, our results lead to a number of applications that are interesting in their own right. 1
Practical identitybased encryption without random oracles
 of LNCS
"... Abstract. We present an Identity Based Encryption (IBE) system that is fully secure in the standard model and has several advantages over previous such systems – namely, computational efficiency, shorter public parameters, and a “tight ” security reduction, albeit to a stronger assumption that depen ..."
Abstract

Cited by 139 (2 self)
 Add to MetaCart
(Show Context)
Abstract. We present an Identity Based Encryption (IBE) system that is fully secure in the standard model and has several advantages over previous such systems – namely, computational efficiency, shorter public parameters, and a “tight ” security reduction, albeit to a stronger assumption that depends on the number of private key generation queries made by the adversary. Our assumption is a variant of Boneh et al.’s decisional Bilinear DiffieHellman Exponent assumption, which has been used to construct efficient hierarchical IBE and broadcast encryption systems. The construction is remarkably simple. It also provides recipient anonymity automatically, providing a second (and more efficient) solution to the problem of achieving anonymous IBE without random oracles. Finally, our proof of CCA2 security, which has more in common with the security proof for the CramerShoup encryption scheme than with security proofs for other IBE systems, may be of independent interest.
Bonsai Trees, or How to Delegate a Lattice Basis
, 2010
"... We introduce a new latticebased cryptographic structure called a bonsai tree, and use it to resolve some important open problems in the area. Applications of bonsai trees include: • An efficient, stateless ‘hashandsign ’ signature scheme in the standard model (i.e., no random oracles), and • The ..."
Abstract

Cited by 124 (6 self)
 Add to MetaCart
(Show Context)
We introduce a new latticebased cryptographic structure called a bonsai tree, and use it to resolve some important open problems in the area. Applications of bonsai trees include: • An efficient, stateless ‘hashandsign ’ signature scheme in the standard model (i.e., no random oracles), and • The first hierarchical identitybased encryption (HIBE) scheme (also in the standard model) that does not rely on bilinear pairings. Interestingly, the abstract properties of bonsai trees seem to have no known realization in conventional numbertheoretic cryptography. 1
CiphertextPolicy AttributeBased Encryption: An Expressive, Efficient, and Provably Secure Realization
"... We present new techniques for realizing CiphertextPolicy Attribute Encryption (CPABE) under concrete and noninteractive cryptographic assumptions. Our solutions allow any encryptor to specify access control in terms of an LSSS matrix, M, over the attributes in the system. We present three differen ..."
Abstract

Cited by 120 (9 self)
 Add to MetaCart
(Show Context)
We present new techniques for realizing CiphertextPolicy Attribute Encryption (CPABE) under concrete and noninteractive cryptographic assumptions. Our solutions allow any encryptor to specify access control in terms of an LSSS matrix, M, over the attributes in the system. We present three different constructions that allow different tradeoffs between the systems efficiency and the complexity of the assumptions used. All three constructions use a common methodology of “directly ” solving the CPABE problem that enable us to get much better efficiency than prior approaches. 1
Cryptographic Cloud Storage
"... We consider the problem of building a secure cloud storage service on top of a public cloud infrastructure where the service provider is not completely trusted by the customer. We describe, at a high level, several architectures that combine recent and nonstandard cryptographic primitives in order ..."
Abstract

Cited by 118 (1 self)
 Add to MetaCart
(Show Context)
We consider the problem of building a secure cloud storage service on top of a public cloud infrastructure where the service provider is not completely trusted by the customer. We describe, at a high level, several architectures that combine recent and nonstandard cryptographic primitives in order to achieve our goal. We survey the benefits such an architecture would provide to both customers and service providers and give an overview of recent advances in cryptography motivated specifically by cloud storage. 1
Anonymous hierarchical identitybased encryption (without random oracles
 In Advances in Cryptology — Crypto 2006, LNCS 4117
"... Abstract. We present an identitybased cryptosystem that features fully anonymous ciphertexts and hierarchical key delegation. We give a proof of security in the standard model, based on the mild Decision Linear complexity assumption in bilinear groups. The system is efficient and practical, with sm ..."
Abstract

Cited by 117 (10 self)
 Add to MetaCart
(Show Context)
Abstract. We present an identitybased cryptosystem that features fully anonymous ciphertexts and hierarchical key delegation. We give a proof of security in the standard model, based on the mild Decision Linear complexity assumption in bilinear groups. The system is efficient and practical, with small ciphertexts of size linear in the depth of the hierarchy. Applications include search on encrypted data, fully private communication, etc. Our results resolve two open problems pertaining to anonymous identitybased encryption, our scheme being the first to offer provable anonymity in the standard model, in addition to being the first to realize fully anonymous HIBE at all levels in the hierarchy. 1
Functional Encryption: Definitions and Challenges
"... We initiate the formal study of functional encryption by giving precise definitions of the concept and its security. Roughly speaking, functional encryption supports restricted secret keys that enable a key holder to learn a specific function of encrypted data, but learn nothing else about the data. ..."
Abstract

Cited by 110 (17 self)
 Add to MetaCart
We initiate the formal study of functional encryption by giving precise definitions of the concept and its security. Roughly speaking, functional encryption supports restricted secret keys that enable a key holder to learn a specific function of encrypted data, but learn nothing else about the data. For example, given an encrypted program the secret key may enable the key holder to learn the output of the program on a specific input without learning anything else about the program. We show that defining security for functional encryption is nontrivial. First, we show that a natural gamebased definition is inadequate for some functionalities. We then present a natural simulationbased definition and show that it (provably) cannot be satisfied in the standard model, but can be satisfied in the random oracle model. We show how to map many existing concepts to our formalization of functional encryption and conclude with several interesting open problems in this young area.