Claudio Orlandi

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We propose a new approach to practical two-party computation secure against an active adversary. All prior practical protocols were based on Yao’s garbled circuits. We use an OT-based approach and get efficiency via OT extension in the random oracle model. To get a practical protocol we introduce a number of novel techniques for relating the outputs and(More)
An additively-homomorphic encryption scheme enables us to compute linear functions of an encrypted input by manipulating only the ciphertexts. We define the relaxed notion of a semihomomorphic encryption scheme, where the plaintext can be recovered as long as the computed function does not increase the size of the input “too much”. We show that a number of(More)
The first and still most popular solution for secure two-party computation relies on Yao’s garbled circuits. Unfortunately, Yao’s construction provide security only against passive adversaries. Several constructions (zero-knowledge compiler, cut-and-choose) are known in order to provide security against active adversaries, but most of them are not efficient(More)
One of the main tools to construct secure two-party computation protocols are Yao garbled circuits. Using the cut-and-choose technique, one can get reasonably efficient Yao-based protocols with security against malicious adversaries. At TCC 2009, Nielsen and Orlandi [28] suggested to apply cut-andchoose at the gate level, while previously cut-and-choose was(More)
Mechanism design deals with distributed algorithms that are executed with self-interested agents. The designer, whose objective is to optimize some function of the agents private <i>types</i>, needs to construct a computation that takes into account agent incentives which are not necessarily in alignment with the objective of the mechanism. Traditionally,(More)
In this paper, we explore the role of privacy-enhancing overlays in Bitcoin. To examine the effectiveness of different solutions, we first propose a formal definitional framework for virtual currencies and put forth a new notion of anonymity, taint resistance, that they can satisfy. We then approach the problem from a theoretical angle, by proposing various(More)
The problem of secure data processing by means of a neural network (NN) is addressed. Secure processing refers to the possibility that the NN owner does not get any knowledge about the processed data since they are provided to him in encrypted format. At the same time, the NN itself is protected, given that its owner may not be willing to disclose the(More)
In the last few years the efficiency of secure multi-party computation (MPC) increased in several orders of magnitudes. However, this alone might not be enough if we want MPC protocols to be used in practice. A crucial property that is needed in many applications is that everyone can check that a given (secure) computation was performed correctly – even in(More)
Zero-knowledge protocols are one of the fundamental concepts in modern cryptography and have countless applications. However, after more than 30 years from their introduction, there are only very few languages (essentially those with a group structure) for which we can construct zero-knowledge protocols that are efficient enough to be used in practice. In(More)
Multiparty computation protocols have been known for more than twenty years now, but due to their lack of efficiency their use is still limited in real-world applications: the goal of this paper is the design of efficient two and multi party computation protocols aimed to fill the gap between theory and practice. We propose a new protocol to securely(More)