Oblivious Transfer (OT) is an important cryptographic tool, which has found its usage in many crypto protocols, such as Secure Multiparty Computations, Certified E-mail and Simultaneous Contract Signing . In this paper, we propose three k-out-of-n OT (OT_k^n) protocols based on additive homomorphic encryption. Two of these protocols prohibit malicious behaviors from a receiver. We also achieve efficient communication complexity bounded by O(l* n) in bits, where l is the size of the encryption key. The computational complexity is comparable to the most efficient existing protocols. Due to the semantic security property, the sender cannot get receiver's selection. When the receiver tries to retrieve more than k values, the receiver is caught cheating with 1-(1/m) probability (Protocol II) or the receiver is unable to get any value at all (Protocol III). We introduce a novel technique based on the solvability of linear equations, which could find its way into other applications. We also provide an experimental analysis to compare the efficiency of the protocols.
Oblivious Transfer (OT) is an important cryptographic tool, which has found its usage in many crypto protocols, such as Secure Multiparty Computations, Certified E-mail and Simultaneous Contract Signing . In this paper, we propose three k-out-of-n OT (OT_k^n) protocols based on additive homomorphic encryption. Two of these protocols prohibit malicious behaviors from a receiver. We also achieve efficient communication complexity bounded by O(l* n) in bits, where l is the size of the encryption key. The computational complexity is comparable to the most efficient existing protocols. Due to the semantic security property, the sender cannot get receiver's selection. When the receiver tries to retrieve more than k values, the receiver is caught cheating with 1-(1/m) probability (Protocol II) or the receiver is unable to get any value at all (Protocol III). We introduce a novel technique based on the solvability of linear equations, which could find its way into other applications. We also provide an experimental analysis to compare the efficiency of the protocols.
Oblivious Transfer (OT) is an important cryptographic tool, which has found its usage in many crypto protocols, such as Secure Multiparty Computations [9], Certified E-mail [2] and Simultaneous Contract Signing [20].In this paper, we propose three k-out-of-n OT (OT n k ) protocols based on additive homomorphic encryption.Two of these protocols prohibit malicious behaviors from both sender and receiver.We also achieve efficient communication complexity bounded by O(l • n) in bits, where l is the size of the encryption key.The computational complexity is same or better than the most efficient existing protocols.Due to the semantic security property, the sender cannot get receiver's selection.When the receiver tries to retrieve more than k values, the receiver is caught cheating with 1 -1/m probability (Protocol II) or the receiver is unable to get any value at all (Protocol III).We introduce a novel technique based on the solvability of linear equations, which could find its way into other applications.We also provide an experimental analysis to compare the efficiency of the protocols.
Oblivious Transfer (OT), a fundamental primitive in cryptography and a cornerstone of Secure Multi-Party Computation (SMPC), is widely applied in privacy-preserving domains. Constructing efficient and secure OT protocols remains an active research area. To address the limitations of existing OT protocols, such as high time complexity and poor scalability, this paper proposes a secure and efficient k-out-of-n oblivious transfer protocol based on the Paillier homomorphic encryption algorithm . The protocol employs a system of multivariate equations to enable the receiver to select k messages from n messages held by the sender. By integrating multi-threaded parallel processing, the computational speed of ciphertext matrix-vector operations is significantly improved. Additionally, plaintext-ciphertext computation replaces traditional encryption methods to optimize the Paillier algorithm’s efficiency for batch data encryption. Experimental results demonstrate that, compared to recent k-out-of-n OT schemes: when n exceeds 30,000 with k=1, the protocol achieves a 200% performance improvement; when n=512 and k=256, it outperforms existing protocols by approximately 100% in overall efficiency.
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 is such a strong cryptographic tool that it is directly used both in private data retrieval techniques and secure, multi-party computation paradigms. We propose an optimal oblivious transfer, where the communication complexity is logarithmic in size of the database with minimum computation overhead - the computational complexity in any oblivious transfer protocol is at least linear in the size of the database. Our communication-efficient oblivious transfer protocol is a non-interactive, single-database scheme that is generally based on homomorphic encryption functions.
Oblivious transfer (OT) protocol is a fundamental building block of cryptography and can be applied widely in many fields. A secure oblivious transfer protocol is supposed to ensure the privacy of both senders and receivers. The privacy of receivers means that the information being selected by receivers would never be revealed to senders. On the other hand, the privacy of senders means that receivers have no further information except for the one that has been selected. In this case, senders are able to deceive receivers by sending same messages. Likewise, in existing 1-out-of-n OT protocols, malicious senders can make all the n messages the same, so that receivers will always get the specific one assigned by senders. This indicates that privacy of receivers wouldnt work under the 1-out-of-n OT protocol. To prevent this kind of attack, this paper provides a general framework on how to design a secure OT protocol based on commutative and ciphertext equality test and take RSA as an example to explain how the protocol is processed.
An m out of n oblivious transfer (OT) protocol is a cryptographic protocol for a sender to transfer m out of n messages to a receiver such that the sender has no idea which m messages are obtained by the receiver (receiver security ) and at the same time the receiver cannot obtain more than m messages ( sender security ). Three such protocols are proposed in [1], which have the advantage that the communication overhead of the protocols is much smaller than that of m implementations of a 1 out of n OT protocol. In this paper we give a security analysis of the three protocols. First we show that the first protocol cannot guarantee both the sender security and the receiver security simultaneously. Next, we point out an obvious security flaw in the second protocol which allows the receiver to obtain all the n messages. The third protocol is nicely designed to be non-interactive. However, we show that the security of the protocol is based on a sort of parallel discrete logarithm problem, instead of the discrete logarithm problem as claimed in the paper. Using the technique of “generalized birthday attack”, the former problem can be solved with a computation complexity much smaller than that required to solve the discrete logarithm problem. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.