In a t-out-n oblivious transfer, the receiver can only receive t messages out of n messages sent by the sender; and the sender has no idea about which ones have been received. Majority of the existing of previous efficient oblivious transfer schemes require t calls of 1-out-n oblivious transfer to construct the t-out-n oblivious transfer. Its computational requirements and bandwidth consumption are quite demanding. Therefore, to guarantee the quality of electronic commercial service, an efficient t-out-n oblivious transfer scheme is urgently desired. Based on the RSA, we propose a new t-out-n oblivious transfer protocol for private information retrieval in this paper. In our method, only several modular multiplications and t hash functions are performed by a user (receiver) to obtain t messages. It is very suitable for the limited computation capacities of receivers such as smart cards or mobile units. Key words: Private information retrieval, security, RSA
In a t-out-n oblivious transfer, the receiver can only receive t messages out of n messages sent by the sender; and the sender has no idea about which ones have been received. Majority of the existing of previous efficient oblivious transfer schemes require t calls of 1-out-n oblivious transfer to construct the t-out-n oblivious transfer. Its computational requirements and bandwidth consumption are quite demanding. Therefore, to guarantee the quality of electronic commercial service, an efficient t-out-n oblivious transfer scheme is urgently desired. Based on the RSA, we propose a new t-out-n oblivious transfer protocol for private information retrieval in this paper. In our method, only several modular multiplications and t hash functions are performed by a user (receiver) to obtain t messages. It is very suitable for the limited computation capacities of receivers such as smart cards or mobile units. Key words: Private information retrieval, security, RSA
Abstract. The most efficient previously proposed oblivious transfer schemes require t calls of 1-out-n oblivious transfer (OT) to construct the t-out-n OT. Its computational requirements and bandwidth consumption are quite demanding. Therefore, to guarantee the quality of growing popular communication service, an efficient t-out-n OT scheme with low bandwidth is urgently desired. Based on elliptic curve cryptosystems, we propose a new t-out-n OT scheme in this paper. Compared with existing OT schemes based on modular exponentiations, our scheme can reduce many computation and communication loads for both the sender and the receiver. Owing to its smaller bandwidth and faster computation speed, our scheme is very suitable for mobile clients and smart-card users. Moreover, our scheme provides a simple algorithm and fewer parameter requirements. Keywords: Two-lock cryptosystem, private information retrieval, elliptic curve 1.
A general approach for constructing t-out-n oblivious transfer is more practical than 1-out-n oblivious transfer for applications. To guarantee the quality of growing popular communication service, an efficient t-out-n oblivious transfer scheme is urgently desired. Based on the RSA and two-lock cryptosystem, we propose an efficient t-out-n oblivious transfer scheme in this paper. Compared with existing oblivious transfer schemes, our scheme can reduce many computations and communications for both the sender and the receiver. Moreover, our scheme is very suitable for smart-card users.
A new k-out-of-n oblivious transfer protocol is presented in this paper. The communication cost of our scheme are n+1 messages of sender to receiver and k messages from the receiver to sender. To the best knowledge of the authors, the communication complexity of our scheme is the least. Also, our scheme has a lower computation cost with (k+1)n modular exponentiations for sender and 3k modular exponentiations for the receiver. The security of our scheme is only based on the Decision Diffie-Hellman assumption. Further, we proved the sender’s computational security and the receiver’s unconditional security under standard model.
Oblivious transfer (OT) protocol is an essential tool in cryptography that provides a wide range of applications such as secure multi-party computation, private information retrieval, private set intersection, contract signing, and privacy-preserving location-based services. The OT protocol has different variants such as one-out-of-2, one-out-of- n , k -out-of- n , and OT extension. In the OT (one-out-of-2, one-out-of- n , and OT extension) protocol, the sender has a set of messages, whereas the receiver has a key. The receiver sends that key to the sender in a secure way; the sender cannot get any information about the received key. The sender encrypts every message by operating on every message using the received key and sends all the encrypted messages to the receiver. The receiver is able to extract only the required message using his key. However, in the k -out-of- n OT protocol, the receiver sends a set of k keys to the sender, and in replay, the sender sends all the encrypted messages. The receiver uses his keys and extracts the required messages, but it cannot gain any information about the messages that it has not requested. Generally, the OT protocol requires high communication and computation cost if we transfer millions of oblivious messages. The OT extension protocol provides a solution for this, where the receiver transfers a set of keys to the sender by executing a few numbers of OT protocols. Then, the sender encrypts all the messages using cheap symmetric key cryptography with the help of a received set of keys and transfers millions of oblivious messages to the receiver. In this work, we present different variants of OT protocols such as one-out-of-2, one-out-of- n , k -out-of- n , and OT extension. Furthermore, we cover various aspects of theoretical security guarantees such as semi-honest and malicious adversaries, universally composable, used techniques, computation, and communication efficiency aspects. From the analysis, we found that the semi-honest adversary-based OT protocols required low communication and computation costs as compared to malicious adversary-based OT protocols.
Abstract. We propose a one-round 1-out-of-n computationally-private information retrieval protocol for ℓ-bit strings with low-degree polylogarithmic receivercomputation, linear sender-computation and communication Θ(k · log 2 n + ℓ · log n), where k is a possibly non-constant security parameter. The new protocol is receiver-private if the underlying length-flexible additively homomorphic public-key cryptosystem is IND-CPA secure. It can be transformed to a one-round computationally receiver-private and information-theoretically sender-private 1out-of-n oblivious-transfer protocol for ℓ-bit strings, that has the same asymptotic communication and is private in the standard complexity-theoretic model. Keywords. Computationally-private information retrieval, length-flexible additively homomorphic public-key cryptosystem, oblivious transfer. 1