Oblivious transfer protocol,which is an important and useful cryptographic protocol,has been widely applied in cryptographic field,especially in construction of secure multi-party computation protocol.However,all of present oblivious transfer protocols have two drawbacks for requirement of their secrets: ① the receiver does not know whether message received is one of the messages held by the sender;② the sender does not know whether message received by the receiver is one of the messages designated by himself.In order to conquer these drawbacks,we firstly introduce the notion of verifiable oblivious transfer protocol,and firstly construct it by using proof protocol of knowledge,i.e.,∑-protocol,as main tool.
Oblivious transfer protocol,which is an important and useful cryptographic protocol,has been widely applied in cryptographic field,especially in construction of secure multi-party computation protocol.However,all of present oblivious transfer protocols have two drawbacks for requirement of their secrets: ① the receiver does not know whether message received is one of the messages held by the sender;② the sender does not know whether message received by the receiver is one of the messages designated by himself.In order to conquer these drawbacks,we firstly introduce the notion of verifiable oblivious transfer protocol,and firstly construct it by using proof protocol of knowledge,i.e.,∑-protocol,as main tool.
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.
Oblivious transfer, first introduced by Rabin, is one of the basic building blocks of cryp-tographic protocols. In an oblivious transfer (or more exactly, in its 1-out-of-2 variant), one party known as the sender has a pair of messages and the other party known as the receiver obtains one of them. Somewhat paradoxically, the receiver obtains exactly one of the messages (and learns nothing of the other), and the sender does not know which of the messages the receiver obtained. Due to its importance as a building block for secure protocols, the efficiency of oblivious transfer protocols has been extensively studied. However, to date, there are almost no known oblivious transfer protocols that are secure in the presence of malicious adversaries under the real/ideal model simulation paradigm (without using general zero-knowledge proofs). Thus, efficient protocols that reach this level of security are of great interest. In this paper we present efficient oblivious transfer protocols that are secure according to the ideal/real model simulation paradigm. We achieve constructions under the DDH, Nth residuosity and quadratic residuosity assumptions, as well as under the assumption that homomorphic encryption exists. 1
The Oblivious Transfer (OT), introduced by Rabin in 1981, has become an important and fundamental cryptography technique. An OT protocol should have two important characteristics: sender's privacy and chooser's privacy. The sender is a party who will deliver a secret to chooser. The chooser is another party who acts as receiver to learn some information about input from sender. The chooser learns of certain information concerning sender's input while sender is not allowed to know what chooser has learned. Moreover, chooser cannot acquire any messages that he/she did not choose. Naor and Pinkas have recently proposed an efficient oblivious transfer protocol (EOT) that implementes 1-out-of-n protocol, but this EOT has a flaw: it cannot withstand the same message attack. In this paper, we will improve Naor and Pinkas EOT and make it resistant to the same message attack.
Oblivious transfer protocol is an important primitive in modern cryptography. Since its introduction, the subject has attracted a lot of attentions and has become the basis for realizing a broad class of cryptographic protocols, such as secret key exchange, contract signing, secure function evaluation, oblivious keyword search, etc. This work describes protocols for proxy oblivious transfer, in which the role of the sender is divided between two proxies, and a receiver (chooser) must contact one proxy in order to run the oblivious transfer protocol and another for some extra information. This proxy oblivious transfer protocol provides a method for the sender to delegate a proxy to transfer one of his messages to a receiver on behalf of him. The proxy oblivious transfer protocol has the same security properties as the oblivious transfer protocol using in our protocol.
Roughly speaking a protocol is a way of exchanging messages so that each party gains some specified information. Correctness and privacy are fundamental constraints to the notion of a secure protocol. Essentially, correctness guarantees that the information the parties learn in executing a protocol is what was specified. Privacy guarantees that they cannot learn more than that. We investigate correctness and privacy for the primitive notion of oblivious transfer protocols. As introduced by Rabin, in an oblivious transfer a party S (the sender) owning a secret message m discloses this message to another party R (the receiver) with probability 1 2 . S does not find out whether R did get the message or not. A different version of this notion (1-out-of-2-oblivious transfer) was introduced by Even, Goldreich and Lempel. Traditionally, correctness and privacy were guaranteed assuming that the parties had bounded computational resources and that some appropriate mathematical problems were in...
Oblivious transfer (OT) protocol is a fundamental cryptographical tool and widely used as a building block of secure computation. In this work, we propose two efficient t -out-of- n oblivious transfer schemes with the designated receiver. A common advantage of the two schemes is efficient. The total computation cost of the sender and the receiver is n +2 t +1 modular exponentiations in first scheme that is three-round, and the total one of the sender and receiver is n +3 t modular exponentiations in second scheme that is two-round. Another advantage of both schemes is designable.