Results 1 - 10 of 134

Fully Secure Functional Encryption: Attribute-Based Encryption and (Hierarchical) Inner Product Encryption

by Allison Lewko, Amit Sahai, Tatsuaki Okamoto, Katsuyuki Takashima, Brent Waters
"... In this paper, we present two fully secure functional encryption schemes. Our first result is a fully secure attribute-based encryption (ABE) scheme. Previous constructions of ABE were only proven to be selectively secure. We achieve full security by adapting the dual system encryption methodology r ..."
Abstract - Cited by 145 (21 self) - Add to MetaCart
In this paper, we present two fully secure functional encryption schemes. Our first result is a fully secure attribute-based encryption (ABE) scheme. Previous constructions of ABE were only proven to be selectively secure. We achieve full security by adapting the dual system encryption methodology recently introduced by Waters and previously leveraged to obtain fully secure IBE and HIBE systems. The primary challenge in applying dual system encryption to ABE is the richer structure of keys and ciphertexts. In an IBE or HIBE system, keys and ciphertexts are both associated with the same type of simple object: identities. In an ABE system, keys and ciphertexts are associated with more complex objects: attributes and access formulas. We use a novel information-theoretic argument to adapt the dual system encryption methodology to the more complicated structure of ABE systems. We construct our system in composite order bilinear groups, where the order is a product of three primes. We prove the security of our system from three static assumptions. Our ABE scheme supports arbitrary monotone access formulas. Our second result is a fully secure (attribute-hiding) predicate encryption (PE) scheme

Improving privacy and security in multi-authority attribute-based encryption

by Melissa Chase, Sherman S. M. Chow - In Proceedings of the 16th ACM Conference on Computer and Communications Security , 2009
"... Attribute based encryption (ABE) [13] determines decryp-tion ability based on a user’s attributes. In a multi-authority ABE scheme, multiple attribute-authorities monitor differ-ent sets of attributes and issue corresponding decryption keys to users, and encryptors can require that a user ob-tain ke ..."
Abstract - Cited by 110 (2 self) - Add to MetaCart
Attribute based encryption (ABE) [13] determines decryp-tion ability based on a user’s attributes. In a multi-authority ABE scheme, multiple attribute-authorities monitor differ-ent sets of attributes and issue corresponding decryption keys to users, and encryptors can require that a user ob-tain keys for appropriate attributes from each authority be-fore decrypting a message. Chase [5] gave a multi-authority ABE scheme using the concepts of a trusted central author-ity (CA) and global identifiers (GID). However, the CA in that construction has the power to decrypt every ciphertext, which seems somehow contradictory to the original goal of distributing control over many potentially untrusted author-ities. Moreover, in that construction, the use of a consistent GID allowed the authorities to combine their information to build a full profile with all of a user’s attributes, which unnecessarily compromises the privacy of the user. In this paper, we propose a solution which removes the trusted cen-tral authority, and protects the users ’ privacy by preventing the authorities from pooling their information on particular users, thus making ABE more usable in practice.
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Fully secure functional encryption with general relations from the decisional linear assumption

by Tatsuaki Okamoto, Katsuyuki Takashima - In CRYPTO , 2010
"... This paper presents a fully secure functional encryption scheme for a wide class of relations, that are specified by non-monotone access structures combined with inner-product relations. The security is proven under a standard assumption, the decisional linear (DLIN) assumption, in the standard mode ..."
Abstract - Cited by 79 (0 self) - Add to MetaCart
This paper presents a fully secure functional encryption scheme for a wide class of relations, that are specified by non-monotone access structures combined with inner-product relations. The security is proven under a standard assumption, the decisional linear (DLIN) assumption, in the standard model. The proposed functional encryption scheme covers, as special cases, (1) key-policy, ciphertext-policy and unified-policy (of key and ciphertext policies) attribute-based encryption with non-monotone access structures, and (2) (hierarchical) predicate encryption with inner-product relations and functional encryption with non-zero

Decentralizing Attribute-Based Encryption

by Allison Lewko, Brent Waters
"... We propose a Multi-Authority Attribute-Based Encryption (ABE) system. In our system, any party can become an authority and there is no requirement for any global coordination other than the creation of an initial set of common reference parameters. A party can simply act as an ABE authority by creat ..."
Abstract - Cited by 76 (9 self) - Add to MetaCart
We propose a Multi-Authority Attribute-Based Encryption (ABE) system. In our system, any party can become an authority and there is no requirement for any global coordination other than the creation of an initial set of common reference parameters. A party can simply act as an ABE authority by creating a public key and issuing private keys to different users that reflect their attributes. A user can encrypt data in terms of any boolean formula over attributes issued from any chosen set of authorities. Finally, our system does not require any central authority. In constructing our system, our largest technical hurdle is to make it collusion resistant. Prior Attribute-Based Encryption systems achieved collusion resistance when the ABE system authority “tied ” together different components (representing different attributes) of a user’s private key by randomizing the key. However, in our system each component will come from a potentially different authority, where we assume no coordination between such authorities. We create new techniques to tie key components together and prevent collusion attacks between users with different global identifiers. We prove our system secure using the recent dual system encryption methodology where the security proof works by first converting the challenge ciphertext and private keys to a semi-functional form and then arguing security. We follow a recent variant of the dual system proof technique due to Lewko and Waters and build our system using bilinear groups of composite order. We prove security under similar static assumptions to the LW paper in the random oracle model. 1
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Reusable garbled circuits and succinct functional encryption

by Shafi Goldwasser, Yael Kalai, Raluca Ada Popa, Vinod Vaikuntanathan, Nickolai Zeldovich , 2013
"... Garbled circuits, introduced by Yao in the mid 80s, allow computing a function f on an input x without leaking anything about f or x besides f(x). Garbled circuits found numerous applications, but every known construction suffers from one limitation: it offers no security if used on multiple inputs ..."
Abstract - Cited by 42 (3 self) - Add to MetaCart
Garbled circuits, introduced by Yao in the mid 80s, allow computing a function f on an input x without leaking anything about f or x besides f(x). Garbled circuits found numerous applications, but every known construction suffers from one limitation: it offers no security if used on multiple inputs x. In this paper, we construct for the first time reusable garbled circuits. The key building block is a new succinct single-key functional encryption scheme. Functional encryption is an ambitious primitive: given an encryp-tion Enc(x) of a value x, and a secret key skf for a function f, anyone can compute f(x) without learning any other information about x. We construct, for the first time, a succinct functional encryption scheme for any polynomial-time function f where succinctness means that the ciphertext size does not grow with the size of the circuit for f, but only with its depth. The security of our construction is based on the intractability of the Learning with Errors (LWE) problem and holds as long as an adversary has access to a single key skf (or even an a priori bounded number of keys for different functions). Building on our succinct single-key functional encryption scheme, we show several new applications in addition to reusable garbled circuits, such as a paradigm for general function obfuscation which we call token-based obfuscation, homomorphic encryption for a class of Turing machines where the evaluation runs in input-specific time rather than worst-case time, and a scheme for delegating computation which is publicly verifiable and maintains the privacy of the computation.
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Functional Encryption for Inner Product Predicates from Learning with Errors

by Shweta Agrawal, Vinod Vaikuntanathan, David Mandell Freeman , 2011
"... We propose a lattice-based functional encryption scheme for inner product predicates whose security follows from the difficulty of the learning with errors (LWE) problem. This construction allows us to achieve applications such as range and subset queries, polynomial evaluation, and CNF/DNF formulas ..."
Abstract - Cited by 39 (12 self) - Add to MetaCart
We propose a lattice-based functional encryption scheme for inner product predicates whose security follows from the difficulty of the learning with errors (LWE) problem. This construction allows us to achieve applications such as range and subset queries, polynomial evaluation, and CNF/DNF formulas on encrypted data. Our scheme supports inner products over small fields, in contrast to earlier works based on bilinear maps. Our construction is the first functional encryption scheme based on lattice techniques that goes beyond basic identity-based encryption. The main technique in our scheme is a novel twist to the identity-based encryption scheme of Agrawal, Boneh and Boyen (Eurocrypt 2010). Our scheme is weakly attribute hiding in the standard model.
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Tools for simulating features of composite order bilinear groups in the prime order setting

by Allison Lewko - In EUROCRYPT , 2012
"... In this paper, we explore a general methodology for converting composite order pairingbased cryptosystems into the prime order setting. We employ the dual pairing vector space approach initiated by Okamoto and Takashima and formulate versatile tools in this framework that can be used to translate co ..."
Abstract - Cited by 37 (4 self) - Add to MetaCart
In this paper, we explore a general methodology for converting composite order pairingbased cryptosystems into the prime order setting. We employ the dual pairing vector space approach initiated by Okamoto and Takashima and formulate versatile tools in this framework that can be used to translate composite order schemes for which the prior techniques of Freeman were insufficient. Our techniques are typically applicable for composite order schemes relying on the canceling property and proven secure from variants of the subgroup decision assumption, and will result in prime order schemes that are proven secure from the decisional linear assumption. As an instructive example, we obtain a translation of the Lewko-Waters composite order IBE scheme. This provides a close analog of the Boneh-Boyen IBE scheme that is proven fully secure from the decisional linear assumption. We also provide a translation of the Lewko-Waters unbounded HIBE scheme. 1

Achieving leakage resilience through dual system encryption

by Allison Lewko, Brent Waters, Yannis Rouselakis - In TCC , 2011
"... In this work, we show that strong leakage resilience for cryptosystems with advanced functionalities can be obtained quite naturally within the methodology of dual system encryption, recently introduced by Waters. We demonstrate this concretely by providing fully secure IBE, HIBE, and ABE systems wh ..."
Abstract - Cited by 28 (5 self) - Add to MetaCart
In this work, we show that strong leakage resilience for cryptosystems with advanced functionalities can be obtained quite naturally within the methodology of dual system encryption, recently introduced by Waters. We demonstrate this concretely by providing fully secure IBE, HIBE, and ABE systems which are resilient to bounded leakage from each of many secret keys per user, as well as many master keys. This can be realized as resilience against continual leakage if we assume keys are periodically updated and no (or logarithmic) leakage is allowed during the update process. Our systems are obtained by applying a simple modification to previous dual system encryption constructions: essentially this provides a generic tool for making dual system encryption schemes leakage-resilient. 1

Mona: Secure Multi-Owner Data Sharing for Dynamic Groups

by Xuefeng Liu , Member, IEEE Yuqing Zhang , Boyang Wang , Jingbo Yan - in the Cloud” IEEE TRANSACTIONS ON PARALLEL AND ISTRIBUTED SYSTEMS, VOL , 2013
"... Abstract-With the character of low maintenance, cloud computing provides an economical and efficient solution for sharing group resource among cloud users. Unfortunately, sharing data in a multi-owner manner while preserving data and identity privacy from an untrusted cloud is still a challenging i ..."
Abstract - Cited by 27 (2 self) - Add to MetaCart
Abstract-With the character of low maintenance, cloud computing provides an economical and efficient solution for sharing group resource among cloud users. Unfortunately, sharing data in a multi-owner manner while preserving data and identity privacy from an untrusted cloud is still a challenging issue, due to the frequent change of the membership. In this paper, we propose a secure multiowner data sharing scheme, named Mona, for dynamic groups in the cloud. By leveraging group signature and dynamic broadcast encryption techniques, any cloud user can anonymously share data with others. Meanwhile, the storage overhead and encryption computation cost of our scheme are independent with the number of revoked users. In addition, we analyze the security of our scheme with rigorous proofs, and demonstrate the efficiency of our scheme in experiments.
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Self-Protecting Electronic Medical Records Using Attribute-Based Encryption

by Joseph A. Akinyele, Christoph U. Lehmann, Matthew D. Green, Matthew W. Pagano, Zachary N. J. Peterson, Aviel D. Rubin
"... We provide a design and implementation of self-protecting electronic medical records (EMRs) using attribute-based encryption. Our system allows healthcare organizations to export EMRs to storage locations outside of their trust boundary, including mobile devices, Regional Health Information Organiza ..."
Abstract - Cited by 26 (0 self) - Add to MetaCart
We provide a design and implementation of self-protecting electronic medical records (EMRs) using attribute-based encryption. Our system allows healthcare organizations to export EMRs to storage locations outside of their trust boundary, including mobile devices, Regional Health Information Organizations (RHIOs), and cloud systems such as Google Health. In contrast to some previous approaches to this problem, our solution is designed to maintain EMR availability even when providers are offline, i.e., where network connectivity is not available (for example, during a natural disaster). To balance the needs of emergency care and patient privacy, our system is designed to provide for fine-grained encryption and is able to protect individual items within an EMR, where each encrypted item may have its own access control policy. To validate our architecture, we implemented a prototype system using a new dual-policy attribute-based encryption library that we developed. Our implementation, which includes an iPhone app for storing and managing EMRs offline, allows for flexible and automatic policy generation. An evaluation of our design shows that our ABE library performs well, has acceptable storage requirements, and is practical and usable on modern smartphones. 1
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