Juan Ramón Troncoso-Pastoriza

Juan Ramón Troncoso-Pastoriza received the M.S. degree in Telecommunications Engineering (Hons) from the University of Vigo, Vigo, Spain, in 2005, when he also received the Best Student Award from the Galician Government and the National Best Graduate Student Award from the Spanish Ministry of Education and Science. He held two consecutive grants from the Spanish Ministry of Education and Science for collaboration with the Telematics Department (2004-2005) and for the development of the Ph.D. Thesis (Formación de Profesorado Universitario, 2006-2011). In 2012, he received the Ph.D. in Telecommunications Engineering (European Doctorate Mention, Hons). His Ph.D. thesis, entitled "Encrypted Domain Processing for Signal Processing Applications," was awarded the Best Ph.D. Thesis by the University of Vigo, and the best Ph.D. Thesis in Spain in Telecommunication Networks and Services by the Spanish Official Institute of Telecommunications Engineers (COIT).

He worked at the Signal Theory and Communications Department in the University of Vigo from 2005 to 2016 as an Associate Researcher, and as a Post-doctoral Researcher at AtlanTTic Research Center for Information and Communication Technologies at the University of Vigo since 2012. Between 2006 and 2007 he visited the Information and Systems Security Department at Philips Research Europe (The Netherlands), where he started working on genomic privacy and filed a PCT international patent application. In 2016, he joined the Laboratory for Communications and Applications 1 at the École Polytechnique Fédérale de Lausanne, Switzerland, as a Post-doctoral researcher to work in genomic privacy-related topics.

He is an elected member of the IEEE Information Forensics and Security Technical Committee and the IEEE Signal Processing Society Student Services Committee for the period 2017-2019. He has been a member of the Technical Program Committee of the IEEE WIFS 2015 and 2017, and part of the organizing committees of IEEE WIFS 2012, ACM IH&MMSEC 2016 and the upcoming EUSIPCO 2018. He has also taken part in several European projects in the area of multimedia security, such as ECRYPT and SPEED, both in FP6; during 2015-2018 he has been the scientific coordinator of the EU H2020 funded project WITDOM, focused on privacy-preserving computation in Cloud. He currently participates in several Swiss projects related to medical privacy and security (DPPH), and application of distributed ledger technologies. He has been reviewer of more than 20 peer-reviewed international journals and more than 30 editions of several international conferences in the field of information security, and serves now as Associate Editor of Elsevier's Digital Signal Processing Journal, EURASIP Journal on Information Security, EURASIP Journal of Visual Communications and Image Representation, and IET Information Security.

He has also participated in several National and regional public-funded projects and private contracts related to information security and privacy protection, an area in which he has coauthored numerous papers in international journals and conferences, and holds four granted international patents in collaboration with Gradiant (Galician Research Center in Advanced Telecommunications).

His past teaching experience covers several undergraduate courses on Communications Theory and Digital Communications in Telecommunications Engineering Bachelor and 5-year degrees at the University of Vigo, and the supervision of multiple semester and master students at EPFL. Additionally, he worked as the network manager and webmaster of the Signal Processing in Communications Group at the University of Vigo from 2009 to 2016, and was the webmaster for the IEEE WIFS 2012.

His research interests include genomic privacy, secure signal processing, applied cryptography for privacy protection and multimedia security.

Bootstrapping for Approximate Homomorphic Encryption with Negligible Failure-Probability by Using Sparse-Secret Encapsulation

Jean-Philippe Léonard Bossuat, Jean-Pierre Hubaux, Juan Ramón Troncoso-Pastoriza

Bootstrapping parameters for the approximate homomorphic-encryption scheme of Cheon et al., CKKS (Asiacrypt 17), are usually instantiated using sparse secrets to be efficient. However, using sparse secrets constrains the range of practical parameters within a tight interval, as they must support a large enough depth for the bootstrapping circuit but also be secure with respect to the sparsity of their secret. We present a bootstrapping procedure for the CKKS scheme that combines both dense and sparse secrets. Our construction enables the use of parameters for which the homomorphic capacity is based on a dense secret, yet with a bootstrapping complexity that remains the one of a sparse secret and with a large security margin. Moreover, this also enables us to easily parameterize the bootstrapping circuit so that it has a negligible failure probability that, to the best of our knowledge, has never been achieved for the CKKS scheme. When using the parameters of previous works, our bootstrapping procedures enable a faster execution with an increased precision and lower failure probability. For example, we are able to bootstrap a plaintext of C-32768 in 20.2 s, with 32.11 bits of precision, 285 remaining modulus bits, a failure probability of 2(-138.7), and 128 bit security.

SPRINGER INTERNATIONAL PUBLISHING AG2022

Efficient protocols for oblivious linear function evaluation from ring-LWE

Juan Ramón Troncoso-Pastoriza

An oblivious linear function evaluation protocol, or OLE, is a two-party protocol for the function f (x) = ax + b, where a sender inputs the field elements a, b, and a receiver inputs x and learns f (x). OLE can be used to build secret-shared multiplication, and is an essential component of many secure computation applications including general-purpose multi-party computation, private set intersection and more. In this work, we present several efficient OLE protocols from the ring learning with errors (RLWE) assumption. Technically, we build two new passively secure protocols, which build upon recent advances in homomorphic secret sharing from (R)LWE (Boyle et al. in: EUROCRYPT 2019, Part II (2019) 3-33 Springer), with optimizations tailored to the setting of OLE. We upgrade these to active security using efficient amortized zero-knowledge techniques for lattice relations (Baum et al. in: CRYPTO 2018, Part II (2018) 669-699 Springer), and design new variants of zero-knowledge arguments that are necessary for some of our constructions. Our protocols offer several advantages over existing constructions. Firstly, they have the lowest communication complexity amongst previous, practical protocols from RLWE and other assumptions; secondly, they are conceptually very simple, and have just one round of interaction for the case of OLE where b is randomly chosen. We demonstrate this with an implementation of one of our passively secure protocols, which can perform more than 1 million OLEs per second over the ring Z(m), for a 120-bit modulus m, on standard hardware.

IOS PRESS2022

Juan Ramón Troncoso-Pastoriza

Bootstrapping for Approximate Homomorphic Encryption with Negligible Failure-Probability by Using Sparse-Secret Encapsulation

Efficient protocols for oblivious linear function evaluation from ring-LWE

Privacy-Preserving and Efficient Verification of the Outcome in Genome-Wide Association Studies

Efficient protocols for oblivious linear function evaluation from ring-LWE

Privacy-Preserving and Efficient Verification of the Outcome in Genome-Wide Association Studies

Bootstrapping for Approximate Homomorphic Encryption with Negligible Failure-Probability by Using Sparse-Secret Encapsulation