Actively Secure OT Extension with Optimal Overhead.

Marcel Keller, Emmanuela Orsini, Peter Schöll

Ignacio Cascudo, René Bødker Christensen, Jaron Skovsted Gundersen

Michele Orrù, Emmanuela Orsini, Peter Schöll

Enrique Larraia

Abstract. On top of the passively secure extension protocol of [IKNP03] we build a new construction secure against active adversaries. We can replace the invocation of the hash function that is used to check the receiver is well-behaved with the XOR of bit strings. This is pos-sible by applying a cut-and-choose technique on the length of the bit strings that the receiver sends in the reversed OT. We also improve on the number of seeds required for the extension, both asymptotically and practically. Moreover, the protocol used to test receiver’s behaviour en-joys unconditional security. 1

Anat Paskin-Cherniavsky

Bo Mi, Darong Huang, Shaohua Wan +2 more

Oblivious transfer (OT) is the most fundamental process in cryptosystems and serves as the basic building block for implementing protocols, such as the secure multi-party computation and the fair electronic contract. However, since most implementations of the Internet of Things are time-sensitive, existing works that are based on traditional public cryptosystems are not efficient or secure under quantum machine attacks. In this paper, we argued that the fastest known 1-out-of-n oblivious transfer (OTn1) protocol, which was proposed by Chou, cannot achieve semantic security and is time-consuming due to exponent arithmetic of large parameters. Utilizing NTRUEncrypt and OT extension, we devised a one-round postquantum secure OTn1protocol that is also proved to be active and adaptively secure under the universal composability framework. Compared with Chou's protocol, the computational overheads of our scheme are approximately 6 and 1.7 times smaller on the sender and receiver sides, in line with the standard security level.