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), 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) 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) 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 (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) 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.
The Oblivious Transfer (OT) protocol is a privacy-preserving two-way communication protocol important for building secure multiparty computations. To exchange symmetric keys, this protocol is typically based on the Rivest—Shamir—Adleman (RSA) or Diffie—Hellman (DH) cryptographic systems, which are used for encryption during the message-encryption phase. However, in existing OT protocols, the generation of multiple pairs of public and private keys and data computations are time-consuming. Using bijective functions to transform the ciphertext within the same ciphertext domain can ensure indistinguishability after decryption and reduce the computational complexity. In the semi-honest model, a ciphertext obfuscation-based OT protocol framework is proposed and OT protocols are instantiated based on RSA and DH within this framework. Compared with RSA-based encryption schemes, the proposed protocol requires only one pair of public and private keys. When the number of public and private keys is reduced to one, the receiver can use the public key in the digital certificate of the sender to implement the OT protocol using an identity authentication function. Compared with the OT protocol based on the DH key exchange, this protocol has a small data transmission volume and low computational complexity. Experimental results show that, compared with existing OT protocols, the efficiency of instantiated protocols in the key exchange stage can be improved by at least 30%. Moreover, this protocol can be used as a basic protocol for privacy set intersections, obfuscation circuits, and OT extension 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