Vandana Guleria

Universally composable issuer-free adaptive oblivious transfer with access policy

In todays Internet world, security, privacy and efficiency are three prime concerns in designing any cryptographic protocol. Adaptive oblivious transfer with access policy AOT-AP is widely used in oblivious search of privacy preserving databases in which each message is associated with an access policy and only authorized receivers can access the databases. All the existing AOT-AP protocols assume a trusted third party called issuer apart from a sender and multiple receivers and are secure under the restriction that the issuer never colludes with a collection of receivers. We propose the first issuer-freeAOT-AP in universal composable UC framework. Our issuer-free AOT-AP is UC secure under standard assumptions assuming malicious adversary in static corruption model. More interestingly, our scheme exhibits significant improvements over the existing schemes. Copyright

Efficient Adaptive Oblivious Transfer in UC Framework

We propose an efficient universally composable (UC) adaptive k-out-of-n (OT

Issuer-Free Adaptive Oblivious Transfer with Access Policy

^{n {\times} 1}_{k}

Lightweight Universally Composable Adaptive Oblivious Transfer

) protocol. Our scheme is proven to be secure in the presence of malicious adversary in static corruption model under the Decision Linear (DLIN) and q-Strong Diffie-Hellman (SDH) assumptions. We use Groth-Sahai proofs and trapdoor commitments of Fischlin et al. The proposed protocol outperforms the existing similar schemes in terms of both communication and computation. More interestingly, our construction guarantees the receiver that he has learnt the correct information at the end of each transfer phase.

Adaptive oblivious transfer with hidden access policy realizing disjunction

Due to the frequent use of Internet in our daily life, privacy is a major issue in designing any cryptographic primitive. Adaptive oblivious transfer with access policy (\(\mathsf{AOT}\)-\(\mathsf{AP}\)) is a widely used primitive to create privacy preserving databases in which different messages have different access policies, allowing only those receivers who have the necessary permissions to access the databases. We provide the first fully-simulatable \(\mathsf{AOT}\)-\(\mathsf{AP}\) without the third party called issuer. To achieve our goal, we present a new ciphertext policy attribute based encryption (CP-ABE), which is a variant of Water’s CP-ABE. The Boneh-Boyen signature is employed to control the malicious behavior of the parties, and proposed CP-ABE is used to encrypt each message of the database under some access policy. The proposed protocol is secure under \(q\)-Strong Diffie-Hellman and \(q\)-Decision Bilinear Diffie-Hellman Exponent assumptions in static corruption model in the presence of malicious adversary. Moreover, our \(\mathsf{AOT}\)-\(\mathsf{AP}\) is as efficient as the existing similar schemes.

Universally Composable Identity Based Adaptive Oblivious Transfer with Access Control

We propose an efficient universally composable (UC) adaptive k-out-of-N oblivious transfer (\({\sf OT}_{k\times 1}^{N }\)) protocol over composite order bilinear group employing Groth-Sahai proofs, Boneh-Boyen signature and Bresson, Catalano and Pointcheval (BCP) encryption. Our scheme is proven to be UC secure in the presence of malicious adversary in static corruption model under decision Diffie-Hellman (DDH), subgroup decision (SD) and l-strong Diffie-Hellman (SDH) assumption. The proposed protocol is lightweight in the sense that it is storage-efficient with low communication and computation overheads as compared to the existing UC secure similar schemes.

Efficient Adaptive Oblivious Transfer Without q-type Assumptions in UC Framework

We propose an efficient adaptive oblivious transfer protocol with hidden access policies. This scheme allows a receiver to anonymously recover a message from a database which is protected by hidden attribute based access policy if the receivers attribute set satisfies the associated access policy implicitly. The proposed scheme is secure in the presence of malicious adversary under the q-Strong Diffie-Hellman (SDH), q-Power Decisional Diffie-Hellman (PDDH) and Decision Bilinear Diffie-Hellman (DBDH) assumption in full-simulation security model. The scheme covers disjunction of attributes. The proposed protocol outperforms the existing similar schemes in terms of both communication and computation.

Haar wavelet collocation method for Lane–Emden equations with Dirichlet, Neumann and Neumann–Robin boundary conditions

We propose the first identity based adaptive oblivious transfer protocol with access control (IBAOT-AC) secure in universal composable (UC) framework. The IBAOT-AC is run between multiple senders, multiple receivers and an issuer. Each sender incorporates its identity and access policies associated with the messages in the generation of ciphertext database. Receivers whose attribute sets satisfy the access policy associated with the message and who interact with a sender generating the corresponding ciphertext can only recover the message. The scheme supports access policy in disjunctive form, thereby, realizes disjunction of attributes. The proposed scheme is UC secure in the presence of malicious adversary under \(q\)-Strong Diffie-Hellman (SDH), Decision Bilinear Diffie-Hellman (DBDH), \(q\)-Decision Bilinear Diffie-Hellman Exponent (DBDHE) and Decision Linear (DLIN) assumptions. The scheme outperforms the existing similar schemes in terms of both communication and computation.

Efficient oblivious transfer with adaptive queries in UC framework

Oblivious transfer is one of the basic building blocks of cryptography. Due to its importance as a building block in the construction of secure multiparty computation protocols, the efficiency and security are two big issues in its design. In this paper, we present an efficient, universal composable UC secure adaptive oblivious transfer without q-type assumptions. The proposed protocol is UC secure under Decision Linear DLIN, Decision Bilinear Diffie-Hellman DBDH and Square Decision Bilinear Diffie-Hellman SqDBDH assumptions in the presence of malicious adversary in static corruption model. The proposed protocol exhibits low computation and communication overheads as compared to the existing similar schemes.

Adaptive Oblivious Transfer Realizing Expressive Hidden Access Policy

Abstract In this paper, we present a numerically stable algorithm based on the Haar wavelet collocation method (hwcm) for numerical solution of a class of Lane–Emden equation with Dirichlet, Neumann and Neumann–Robin type boundary conditions, arising in various physical models. The Haar wavelet collocation method uses simple box functions and hence the formulation of the numerical algorithm is straightforward. Unlike other methods, the hwcm can be applied easily and accurately to the Neumann type boundary conditions. The advantage of the Haar wavelet method is its efficiency and simple applicability for a variety of boundary conditions. The Haar wavelet collocation method is utilized to reduce the Lane–Emden equation with boundary conditions to a system of algebraic equations, then the Newton’s method is employed for numerical solutions. Nine examples of the Lane–Emden equation with various types of boundary conditions are provided to demonstrate the accuracy and efficiency of the hwcm. The numerical results are compared with the results obtained by other techniques and the exact solution.