Matthew Tsao, Kaidi Yang, Stephen Zoepf, Marco Pavone
The era of big data has brought with it a richer understanding of user behavior through massive datasets, which can help organizations optimize the quality of their services. In the context of transportation research, mobility data can provide municipal authorities (MAs) with insights on how to operate, regulate, or improve the transportation network. Mobility data, however, may contain sensitive information about end users and trade secrets of mobility providers (MPs). Due to this data privacy concern, MPs may be reluctant to contribute their datasets to MA. Using ideas from cryptography, we propose an interactive protocol between an MA and an MP, in which MA obtains insights from mobility data without MP having to reveal its trade secrets or sensitive data of its users. This is accomplished in two steps: 1) a commitment step and 2) a computation step. In the first step, Merkle commitments and aggregated traffic measurements are used to generate a cryptographic commitment. In the second step, MP extracts insights from the data and sends them to MA. Using the commitment and zero-knowledge proofs, MA can certify that the information received from MP is accurate, without needing to directly inspect the mobility data. We also present a differentially private version of the protocol that is suitable for the large query regime. The protocol is verifiable for both MA and MP in the sense that dishonesty from one party can be detected by the other. The protocol can be readily extended to the more general setting with multiple MPs via secure multiparty computation.
This PhD thesis focuses on lattice-based cryptography and how to apply it to build post-quantum online voting systems. It is the result of the research done by the author at Scytl in close collaboration with Dr. Paz Morillo, from the Department of Applied Mathematics at UPC and Ramiro Martínez, PhD student. As part of her work at the electronic voting company Scytl, the author has participated in the design of several electronic voting systems as well as in their implementation, by providing support to the development team. Nevertheless, all these systems use standard and well-known cryptographic primitives, i.e., not lattice-based primitives, to ensure that the security requirements are fulfilled. Due to this, one of the main challenges of this PhD has been to start researching on a field which was not familiar to the author and contribute to its state of the art. This has allowed the company to enter the post-quantum world by participating in a project which aims to implement a lattice-based online voting system. The thesis has the following contents: an introduction to the lattice theory by describing some of its basic concepts and the computational problems in which the security of lattice-based cryptosystems relies. In this first part it is also described in detail those cryptosystems that are used as building blocks of three new protocols proposed in the thesis: a lattice-based coercion-resistant cast-as-intended protocol, a post-quantum mix-net and a fully post-quantum proof of a shuffle. The former is the lattice version of an existing protocol and allows the voter to check that the vote cast contains the selected voting options. The second and third protocols are the result of the research on lattice-based mix-nets. Two constructions are proposed: the first one allows to demonstrate that a mix-node has permuted and re-encrypted a list of RLWE ciphertexts without modifying them, but it cannot be considered fully post-quantum since the binding property of the commitment scheme relies on classical computational problems. The second one is fully post-quantum since all the cryptographic schemes used for building it, i.e., commitment scheme and zero-knowledge proofs, are based on lattices. Last but not least, for this second proposal a security definition and a proof of security are also provided. Finally, the last part of the thesis consists of building a post-quantum online voting system using as building blocks the protocols already presented and existing lattice-based constructions. This system is considered secure under quantum attacks and provides long-term privacy. It also guarantees vote anonymity, vote authenticity, vote integrity, individual verifiability and receipt-freeness. The algorithms involved in each phase are described in detail as well as the interaction among the participants. An implementation of this system is not given as part of this thesis although a lattice-based online voting system based on that is already being implemented at the company. Aquest tesi es centra en la criptografia basada en reticles i com aplicar-la a la construcció de sistemes de votació electrònica post-quàntics. És el fruit de la recerca feta per l'autora de la tesi a Scytl en estreta col·laboració amb la Dra. Paz Morillo, del Departament de Matemàtica Aplicada de la UPC i en Ramiro Martínez, estudiant de doctorat. Com a part de la seva feina a l'empresa de vot electrònic Scytl, l'autora ha participat tant en el disseny de sistemes de votació electrònica com en la seva implementació, donant suport a l'equip de desenvolupament. No obstant, tots aquests sistemes utilitzen primitives criptogràfiques estàndard (primitives no basades en reticles) per assegurar que els requisits de seguretat es compleixen, i és per aquest motiu que un dels principals reptes d'aquest doctorat ha estat fer en recerca en un camp que no era familiar per l'autora, i contribuir-hi. Per altra banda, això ha permès a l'empresa endinsar-se en el món post-quàntic i participar en un projecte que té per objectiu implementar un sistema de vot electrònic basat en reticles. Aquest tesi consta dels següents continguts: una introducció a la teoria dels reticles on es descriuen alguns dels seus conceptes bàsics i els problemes computacionals dels quals depèn la seguretat dels criptosistemes basats en reticles. En aquesta primera part també es descriuen en detall aquells criptosistemes utilitzats en la construcció dels tres nous protocols presentats en aquesta tesi: un protocol basat en reticles resistent a la coacció i que ofereix verificabilitat “cast-as-intended”; una “mix-net post-quàntica” i una prova de coneixement nul totalment post-quàntica que permet demostrar que la barreja de vots s'ha realitzat correctament. El primer protocol és la versió basada en reticles d'un protocol ja existent i permet que el votant comprovi que el vot emès conté les opcions que havia seleccionat. El segon i el tercer protocol són el resultat de la recerca feta en el camp de les mix-nets basades en reticles. Es proposen dues construccions: la primera d'elles permet demostrar que un node de la mix-net ha barrejat i rexifrat una llista de xifrats RLWE sense modificar-los, però no es pot considerar totalment post-quàntica ja que la propietat de lligar de l'esquema de compromís utilitzat per construir la prova es basa en problemes computacionals clàssics. La segona construcció és totalment post-quàntica ja que tots els esquemes criptogràfics utilitzats en el seu disseny, és a dir, esquema de compromís i proves de coneixement nul, estan basats en reticles. Finalment, però no per això menys important, per aquesta segona proposta també es dóna una definició de seguretat i una prova de seguretat. L'última part de la tesi consisteix en construir un sistema de vot online post-quàntic, utilitzant com a components els protocols prèviament presentats i construccions ja existents basades en reticles. El sistema es considera segur en front atacs quàntics i ofereix privadesa a llarg plaç. També garanteix l'anonimat del vot, la seva autenticitat i integritat, verificabilitat individual i resistència a la coacció. Es descriuen en detall tant els algoritmes executats a cada fase com la interacció entre els seus participants. Com a part de la tesi no s'inclou cap implementació del sistema tot i que l'empresa està implementant un sistema de vot online basat en el que es presenta en aquesta tesi.
Pedro Miguel Martínez-Gironés, Javier Vera-Olmos, Mario Gil-Correa, Ana Ramos · 8 authors
Typically, pseudo-Computerized Tomography (CT) synthesis schemes proposed in the literature rely on complete atlases acquired with the same field of view (FOV) as the input volume. However, clinical CTs are usually acquired in a reduced FOV to decrease patient ionization. In this work, we present the Franken-CT approach, showing how the use of a non-parametric atlas composed of diverse anatomical overlapping Magnetic Resonance (MR)-CT scans and deep learning methods based on the U-net architecture enable synthesizing extended head and neck pseudo-CTs. Visual inspection of the results shows the high quality of the pseudo-CT and the robustness of the method, which is able to capture the details of the bone contours despite synthesizing the resulting image from knowledge obtained from images acquired with a completely different FOV. The experimental Zero-Normalized Cross-Correlation (ZNCC) reports 0.9367 ± 0.0138 (mean ± SD) and 95% confidence interval (0.9221, 0.9512); the experimental Mean Absolute Error (MAE) reports 73.9149 ± 9.2101 HU and 95% confidence interval (66.3383, 81.4915); the Structural Similarity Index Measure (SSIM) reports 0.9943 ± 0.0009 and 95% confidence interval (0.9935, 0.9951); and the experimental Dice coefficient for bone tissue reports 0.7051 ± 0.1126 and 95% confidence interval (0.6125, 0.7977). The voxel-by-voxel correlation plot shows an excellent correlation between pseudo-CT and ground-truth CT Hounsfield Units (m = 0.87; adjusted R2 = 0.91; p < 0.001). The Bland–Altman plot shows that the average of the differences is low (−38.6471 ± 199.6100; 95% CI (−429.8827, 352.5884)). This work serves as a proof of concept to demonstrate the great potential of deep learning methods for pseudo-CT synthesis and their great potential using real clinical datasets.
We propose the first generalization of the famous Non-Interactive Zero-Knowledge (NIZK) proofs to quantum languages (NIZKoQS) and we provide a protocol to prove advanced properties on a received quantum state non-destructively and non-interactively (a single message being sent from the prover to the verifier). In our second orthogonal contribution, we improve the costly Remote State Preparation protocols [Cojocaru et al. 2019 ; Gheorghiu and Vidick 2019 ] that can classically fake a quantum channel (this is at the heart of our NIZKoQS protocol) by showing how to create a multi-qubit state from a single superposition. Finally, we generalize these results to a multi-party setting and prove that multiple parties can anonymously distribute a GHZ state in such a way that only participants knowing a secret credential can share this state, which could have applications to quantum anonymous transmission, quantum secret sharing, quantum onion routing and more.
LibSWIFFT is an open-source, production-ready C/C++ library providing SWIFFT, one of the fastest available secure hash functions that is also collision-resistant. SWIFFT also facilitates post-quantum digital signature schemes and zero-knowledge proofs of knowledge of a preimage (ZKPoKP). LibSWIFFT is optimized for short blocks of input and runs at a rate of less than 5 cycles/byte single-threaded on a modern commodity computer with AVX2. Other software providing SWIFFT, which are not claiming production-readiness as LibSWIFFT is, are the original implementation by the authors of SWIFFT (Micciancio, 2016) and the SWIFFT 8-bit (Karati & Safavi-Naini, 2018b) and 16-bit (Karati & Safavi-Naini, 2018a) AVX2 implementations for the multi-signature scheme K2SN-MSS (Karati & Safavi-Naini, 2019).
We propose the first generalization of the famous Non-Interactive\nZero-Knowledge (NIZK) proofs to quantum languages (NIZKoQS) and we provide a\nprotocol to prove advanced properties on a received quantum state\nnon-destructively and non-interactively (a single message being sent from the\nprover to the verifier).\n In our second orthogonal contribution, we improve the costly Remote State\nPreparation protocols [CCKW18,CCKW19,GV19] that can classically fake a quantum\nchannel (this is at the heart of our NIZKoQS protocol) by showing how to create\na multi-qubits state from a single superposition.\n Finally, we generalize these results to a multi-party setting and prove that\nmultiple parties can anonymously distribute a GHZ state in such a way that only\nparticipants knowing a secret credential can share this state, which could have\napplications to quantum anonymous transmission, quantum secret sharing, quantum\nonion routing and more.\n
Non-interactive zero-knowledge (NIZK) proofs for chosen-ciphertext security are generally considered to give an impractical construction. An interesting recent work by Seo, Abdalla, Lee, and Park (Information Sciences, July 2019) proposed an efficient semi-generic conversion method for achieving chosen-ciphertext security based on NIZK proofs in the random oracle model. The recent work by Seo et al. demonstrated that the semi-generic conversion method transforms a one-way (OW)-secure key encapsulation mechanism (KEM) into a chosen-ciphertext secure KEM while preserving tight security reduction. This paper shows that the security analysis of the semi-generic conversion method has a flaw, which comes from the OW security condition of the underlying KEM. Without changing the conversion method, this paper presents a revised security proof under the changed conditions that (1) the underlying KEM must be chosen-plaintext secure in terms of indistinguishability and (2) an NIZK proof derived from the underlying KEM via the Fiat–Shamir transform must have the properties of zero-knowledge and simulation soundness. This work extended the security proof strategy to the case of identity-based KEM (IBKEM) and also revise the security proof for IBKEM of previous method by Seo et al. Finally, this work gives a corrected security proof by applying the new proofs to several existing (IB)KEMs.
In addition to their usefulness in proving one’s identity electronically, identification protocols based on zero-knowledge proofs allow designing secure cryptographic signature schemes by means of the Fiat–Shamir transform or other similar constructs. This approach has been followed by many cryptographers during the NIST (National Institute of Standards and Technology) standardization process for quantum-resistant signature schemes. NIST candidates include solutions in different settings, such as lattices and multivariate and multiparty computation. While error-correcting codes may also be used, they do not provide very practical parameters, with a few exceptions. In this manuscript, we explored the possibility of using the error-correcting codes proposed by Stakhov in 2006 to design an identification protocol based on zero-knowledge proofs. We showed that this type of code offers a valid alternative in the error-correcting code setting to build such protocols and, consequently, quantum-resistant signature schemes.
Computed tomography imaging spectrometry (CTIS) is a snapshot hyperspectral imaging technique that can obtain a three-dimensional (${2D +}\lambda$) data cube of the target scene within a single exposure. Previous studies of CTIS suggest that reconstructions usually suffer from severe artifacts due to the limited number of projections available. To overcome this limitation, an iterative algorithm combining superiorization and guided image filtering is proposed to explore the intrinsic properties of the hyperspectral data cube as well as the characteristics of zero-order diffraction for the first time, to the best of our knowledge. Results from both simulative studies and proof-of-concept experiments demonstrate its superiority in suppressing artifacts and improving precision over the frequently used expectation maximization algorithm.
The insurance business is characterized by complicated transactional interrelationships among various stakeholders involved in insurance-related activities. Given this unique nature, the century-old challenge in the insurance industry is to effectively reduce transaction costs among the stakeholders while maintaining business privacy and trust. Although blockchain is a promising technology to mitigate this challenge, two technical issues, namely (1) inefficiency in data auditing and (2) difficulty in verifying encrypted data, are of strategic importance when applying blockchain to the insurance industry. To address these technical challenges, we propose an innovative blockchain-based technical model, InsurModel, in the context of newly initiated long-term care insurance in China. Specifically, we utilize cryptographical methods including “zero-knowledge-proof” to 1) represent business interdependence and 2) verify confidential business information without disclosure of specifics. We demonstrate the scalability and applicability of InsurModel and explore its strategic implications in constraining adverse behaviors of the stakeholders.
Abdel Ali Harchaoui, Ali Younes, Abdelaaziz El Hibaoui, Ahmed Bendahmane
Proof of Retrievability (PoR) is a technique used to ensure the authenticity of data on outsourced storage services. It improves the soundness and the robustness of the data integrity scheme and allows clients to recover the remote data. Under the circumstance of considering untrusted parties including the Cloud Storage Provider (CSP) and Third Party Authenticator (TPA), incorporating PoR and zero-knowledge Proofs, which is another technique used to allow a prover to convince a verifier that a secret exists without revealing the secret itself, will ensure client integrity verification, strengthen privacy, and improve fairness to both sides. In this paper, we present, on one hand, the state-of-the-art of PoR under zero-knowledge constructs following an existing data integrity scheme taxonomy of cloud storage. We analyze the PoR scheme formalism and its similarities with zero-knowledge concepts, in addition to the techniques used to settle robustness and zero-knowledge proofs methods. On the other hand, we propose our improved taxonomy of proofs of retrievability enriched by the zero-knowledge, the cryptography model, and the cryptographic setup. The proposed taxonomy equips researchers with a tool to think about the PoR scheme from those perspectives. In the end, we state some fruitful lines of works that PoR can take advantage of; i.e Bulletproofs, Interactive Oracle Proofs, and Interactive Oracle Proofs of Proximity For Reed-Solomon.
Financial Regulation is a form of compliance system that subjects financial institutions to certain requirements and restrictions. Investment Compliance is an example that involves investment restrictions and monitoring on behalf of investors. Hedge Funds differ from other traditional funds such as mutual funds because of their ability to employ complex investment and hedging techniques. These are private entities with few public disclosure requirements. This is useful in a way as the strategies used are confidential which allows financial agents to participate in the financial markets without any fear of information leakage, hence promoting liquidity. However, this is often implied as a lack of transparency. Hedge Funds are expected to produce higher returns, but sometimes investors seek a risk guarantee in addition to higher returns. However, too much transparency rules out the incentives financial entities have by participating in the first place. On the other hand, too much secrecy may give rise to malicious entities that can break the rules due to a lack of compliance. We aim to solve this problem of protecting investors while ensuring the privacy of financial bodies using zero knowledge proofs. Proofs can be visualized as a way of providing enough information to investors while the zero-knowledge property of proofs maintains the privacy of the fund manager’s strategies. We propose a protocol to address this scenario using Zokrates, a framework for verifiable computation using Zk-SNARKs on Ethereum, to encode the constraints and export the verifier. Based on our implementation and analysis, it can be concluded that zero knowledge proofs provide us with a variety of ways to develop compliance systems.
As we reflect on 75 years of experimental publications in Plastic and Reconstructive Surgery, a few thoughts come to mind. The first is how far we have come as a field. Investigations have progressed from simple observations of the natural history of transferred tissue to mechanistic descriptions of intracellular alterations and the integration of emerging technologies in reconstructive procedures. The second is the astonishing breadth of the field. Essentially, plastic surgery has laid claim to all of human anatomy and its associated functions, yet we are constrained to none. The third is the pervasive sense of exhilaration in exploration. Perhaps the reason for the latter is that plastic surgery has always been a specialty defined by autonomy of thought in pursuit of solutions, unified only by the central objective of structural and functional restoration. Thus, the inherent nature of the specialty is one that is built on fundamental research and continually evolves through innovation and discovery. On the seventy-fifth anniversary of Plastic and Reconstructive Surgery, we will discuss some of the major advances in plastic surgery research, highlight some landmark discoveries over the years, and, of course, mention some of our personal favorites. Tissue Transfer and Transplantation In the first issue of Plastic and Reconstructive Surgery in 1946, Lyndon Peer published his innovative and unconventional experiments to better understand the growth of pediatric cartilage grafts.1 To do this, he implanted autogenous cartilage grafts, from various anatomical locations, into infants and children and explanted them a few years later. From these experiments, he concluded that the cartilage grafts grew: maybe. As unusual as it may have been to perform these experiments, particularly in infants and children, he was pursuing one of the primary areas of interest in plastic surgery investigation: the quest to understand the impact of tissue transfer and remodeling. In the 1940s to 1950s, the ideas of moving autologous or homologous tissues were simultaneously developing. Early studies in vascularized autologous tissue transfer were focused on methods to improve flap vascularity and techniques to monitor flap perfusion. From a historical perspective, one of our favorite advances during this period was the repurposing of Millikan’s ear oximeter, originally designed for pilots during World War II and credited as the origin of modern pulse oximetry, for perfusion monitoring of pedicled flaps following transfer.2 Regarding autologous tissue transfer, perhaps the most consequential advance occurred in 1957, when Harry J. Buncke developed techniques for transferring blocks of tissue on 1-mm vessels. He subsequently demonstrated successful replantation of digits and ears in animal models (Fig. 1).3 Shortly after the first report by Buncke, Goldwyn observed that viability of large, pedicled island flaps was improved with microvascular anastomoses, predicting the possibility of free tissue transfer.4 These pioneers of microsurgery sparked a decade of microsurgical advances starting with the proof-of-principle demonstration by Krizek et al. of the first abdominal musculocutaneous free flaps in a canine model,5 followed by the introduction of functional free flaps with neurotization by Tamai et al.,6 and the addition of bone by Ostrup and Fredrickson,7 culminating in clinical translation in 1973.8Fig. 1.: The birth of microsurgery. Before the work by Buncke and Schulz in 1965, salvage of amputated fingers was attempted by means of grafting of either composite tissues or osseous components under a pedicled flap. During the late 1950s and 1960s, the increase in understanding of transferring tissues on microanastomoses suggested that replantation of an entire digit may be possible. Thus, Buncke and Schulz designed a set of animal experiments using a rhesus monkey model to best imitate human finger replantation. In their series of nine experimental replantations, only one survived (experiment 6, animal 5). However, the success of this one experiment was the proof-of-principle result that opened the field of microsurgery. Vessel clamped and measured at 0.8 mm in diameter (above, left); microanastomosis (below, left). Experiment 6 at 2 weeks after surgery (center) and animal 5 with replanted finger at 3 months after surgery (right). (Reprinted with permission from Buncke HJ, Schulz WP. Experimental digital amputation and reimplantation. Plast Reconstr Surg. 1965;36:62–70.)Simultaneously, consideration of allogeneic sources for tissue transfer was expanding in the postwar era, with an emphasis on methods of banking skin allografts9 and reducing allograft rejection with varying techniques such as radiation therapy and steroid administration.10,11 After the reports from Murray et al. regarding renal allotransplantation,12,13 attention shifted to vascularized composite tissues, converging with the gains in microsurgical techniques. One of the first attempts at understanding vascularized composite allotransplantation was performed by Goldwyn et al. in 1966 using canine limbs (Fig. 2).14 Although all of the allotransplants in this study ultimately failed, they demonstrated that rudimentary immunosuppression delayed rejection. Remarkably, they also observed that different tissue types exhibited variable rejection rates, astutely foreshadowing the work by Lee et al. in 1991 demonstrating differences in antigenicity of tissue types.15 Over the course of the 1970s to 1990s, progressive developments in the understanding of free flap perfusion16–20 and transplant immunology21–26 gradually reduced the morbidity in autologous transfer, increased the functionality of autologous transfer, and culminated in clinical translation of vascularized composite allotransplants.Fig. 2.: Early vascularized composite allotransplantation. Unlike replantation, few attempts at understanding extremity allotransplantation were occurring until the 1960s. Inspired by a clinical report of a failed extremity allotransplant, Goldwyn and colleagues sought to understand the effects of immunosuppression in their seminal study of canine limb allotransplantation. Although all of the transplants were ultimately rejected, the authors demonstrated that immunosuppression delayed rejection reliably and that tissue types varied in their rates of rejection. Shown is a femoral arteriogram of an azathioprine-treated canine limb allotransplant at postoperative day 18 with patent distal arteries. (Reprinted with permission from Goldwyn RM, Beach PM, Feldman D, Wilson RE. Canine limb homotransplantation. Plast Reconstr Surg. 1966;37:184–195.)Synthesizing Tissue and Creating Function The second exciting area of plastic surgery investigation was focused on the idea of synthesizing tissue and creating function. The major differences between the two areas of investigation are that the latter has a rebellious streak, breaking all the rules of nature by creating function in an area devoid of function; plastic surgery is still in its infancy in this area. Although the idea of synthesizing tissue is age-old, the ability to do so has been very challenging. The first attempt to synthesize tissue was presented in Plastic and Reconstructive Surgery in 1952 by Kathryn Lyle Stephenson, who implanted cartilage extracts into rodent muscles and supplemented them with hormones to create ectopic cartilage.27 Unfortunately, these experiments were unsuccessful, but they stimulated a series of novel experiments that would ultimately become the field of regenerative medicine. The ensuing two decades saw few investigations in regenerative medicine until the exceptional work of Snyder et al. in 1973, where they described successful mandibular distraction osteogenesis in a canine model (Fig. 3).28 These experiments were ultimately translated into the clinical arena by McCarthy et al. 20 years later.29 The study by Snyder et al., in concept, is one of our favorites in that distraction was and continues to be one of the only examples of completely endogenous, clinically useful, surgically practical tissue synthesis.Fig. 3.: Regenerating bone. Although gains in clinical knowledge have occurred for both autologous and homologous tissue transfer, tissue synthesis has yet to enter the clinical arena in a substantial manner, with the exception of distraction osteogenesis. Inspired by the ideas of lengthening bones, Snyder et al. hypothesized that the same concepts could be applied to the facial skeleton. In a canine model, Snyder and colleagues surgically created a shortened mandible such that a severe crossbite was present. After 6 weeks of healing, the authors osteotomized the mandible and placed an external fixator (left) that was lengthened at a rate of 1 mm/day for 14 days and consolidated for 6 weeks. At the end of the consolidation period, a radiograph was taken (right) demonstrating bony healing. This pilot experiment by Snyder and colleagues in 1973 eventually led to the clinical translation of mandibular distraction by McCarthy et al. and is one of the only examples of tissue synthesis that has reached the clinical realm. (Reprinted with permission from Snyder CC, Levine GA, Swanson HM, Browne EZ Jr. Mandibular lengthening by gradual distraction: Preliminary report. Plast Reconstr Surg. 1973;51:506–508.)During the 1980s, the idea that biological tissue could be synthesized by artificial materials started to crystallize. One of the most significant additions to the literature during that period was the description and eventual conceptual clinical translation of an artificial biomaterial guiding peripheral nerve regeneration in a rat sciatic nerve model by Seckel et al. (Fig. 4)30 and in a nonhuman primate model by Dellon and Mackinnon.30,31 This concept was shortly followed by investigations on creating other tissues, such as cartilage,32 using the same strategy of synthetic, biodegradable polymers with incorporated cellular material. Vacanti and colleagues demonstrated the most dramatic example with the culturing and in vivo implantation of chondrocytes on a polymeric scaffold in the shape of an ear.33–35 However, despite the incredible enthusiasm generated by seeing human ears on the backs of nude mice, long-term stability in immunocompetent settings remains elusive.Fig. 4.: Guiding regeneration with materials. The 1980s were marked by an increasing interest in guiding regeneration with scaffolding materials. Two groups, Seckel et al. and Dellon and Mackinnon, demonstrated in two different animal models that peripheral nerve gaps could be successfully regenerated with the interposition of a resorbable polymeric nerve guide to span the gap. These studies ushered in a vast number of investigations using resorbable materials as an inert scaffold for delivery of trophic factors or cells for a variety of tissue types. Shown is the experimental design using rat sciatic nerve gaps as described by Seckel and colleagues. (Reprinted with permission from Seckel BR, Chiu TH, Nyilas E, Sidman R. Nerve regeneration through synthetic biodegradable nerve guides: Regulation by the target organ. Plast Reconstr Surg. 1984;74:173–181.)The concept of guiding tissue regeneration gained in popularity and became an area of intense investigation in the 1990s to 2000s. In particular, there was an explosion of interest in growth factors and growth factor delivery, especially bone morphogenetic proteins in the realm of bone regeneration.36–39 However, around 2009, it started to become clear that supraphysiologic dosages of growth factors were unlikely to be reasonable clinical solutions for regeneration. Although tissue could be regenerated, the complete lack of control over that regeneration, with no reliable approaches to stop that growth, created regulatory barriers to clinical translation.40 Particularly with the concurrent revelations on the complexity of calvarial suture biology by Roth et al.,41–44 the conclusion emerged that bone regeneration was unlikely to be accomplished by any one single factor but rather was the summation of multiple cues from a defined microenvironment. Over the past decade, technological advances at both the micro and macro levels have allowed us to truthfully ask the question of whether recapitulation of nature is absolutely necessary for functional restoration. At the micro level, efforts have shifted in the direction of fabricating microenvironments that may not be identical to the mature tissue itself, but the milieu necessary to generate the mature tissue over time. That is, single-tissue regeneration has evolved toward integrating sophisticated and tunable biomaterials tailored to globally organize multicellular responses with the goal of eliminating delivery of exogenous growth factors or ex vivo–expanded progenitor cells. The challenge now lies in detailed characterization of cell-material interactions. At the macro level, technological advances in engineering and robotics beg the question about whether functional replacement requires biological tissues. In the realm of limb loss, advances in prosthetics are arguably outpacing the possibilities of safe immunosuppression. In other words, design and implementation of the interfaces between biology and machinery may replace the need for transfer of composite biological tissues for optimal function.45–48 The evolution of the two major lines of plastic surgery investigation is truly a reflection of the spirit of plastic surgery, interrelated yet boundless in the incorporation of new ideas and fields of study. Ultimately, plastic surgery has always been the home for the creative people in medicine; the idealists who believe that there is a solution to everything; the eternal optimists who see zero limits, only challenges to be accepted; and the extraordinary people who rejected the mundane and instead chose the adventure (Fig. 5). We enthusiastically look forward to the evolution of the next 75 years, which are sure to be just as thrilling as the first.Fig. 5.: Over the past 75 years of experimental publications in Plastic and Reconstructive Surgery, investigations have progressed from simple observations of the natural history of transferred tissue to mechanistic descriptions of intracellular alterations and the integration of emerging technologies in reconstructive procedures. Plastic surgery has always been a specialty defined by autonomy of thought in pursuit of solutions, unified only by the central objective of structural and functional restoration. The inherent nature of the specialty is one that is built on fundamental research and continually evolves through innovation and discovery.
Organ and Tissue Transplantation Research
Reconstructive Surgery and Microvascular Techniques
Digital Rights Management (DRM) is a basic requirement in the Internet era. In order to solve the disadvantages caused by centralization in traditional DRM, many decentralized DRM (DDRM) structure are proposed, and they have achieved decentralization in copyright registration, copyright trading, etc. However, the distribution of content keys is their bottleneck. Different from public copyright and transaction information, content key which is used for digital content decryption cannot be directly disclosed to decentralized nodes. The existing DDRM relies on specific nodes or an ideal trust environment to issue encrypted content keys, which makes the system unable to be completely decentralized. In this paper, we proposed a decentralized key distribution system, and it can be compatible with the existing DDRM structure. We use zero-knowledge proof technology to prove to others the correctness of the encrypted content key without revealing it. We use blockchain technology to achieve decentralized key distribution, without relying on any trusted center. Our system allows consumers and agents to apply for and distribute content keys without trusting each other. Malicious users cannot commit fraud against others, and damaged nodes will not affect the stability and reliability of the system.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
The security and privacy of healthcare enterprises (HEs) are crucial because they maintain sensitive information. Because of the unique functional requirement of omni-inclusiveness, HEs are expected to monitor patients, allowing for connectivity with vehicular ad hoc networks (VANETs). In the absence of literature on security provisioning frameworks that connect VANETs and HEs, this paper presents a smart zero-knowledge proof and statistical fingerprinting-based trusted secure communication framework for a fog computing environment. A zero-knowledge proof is used for vehicle authentication, and statistical fingerprinting is employed to secure communication between VANETs and HEs. Authenticity verification of the operations is performed at the on-board unit (OBU) fitted in the vehicle based on the service executions at the resident hardware platform. The processor clock cycles are acquired from the service executions in a complete sandboxed environment. The calculated cycles assist in developing the blueprint signature for the particular OBU of the vehicle. Hence, the fingerprint signature helps build trust and plays a key role in authenticating the vehicle's horizontal movement to everything or to different sections of the HEs. In an environment enabled for fog computing, our novel model can provide efficient remote monitoring.
Elliptic curves with a bilinear map, or pairing, have a rich algebraic structure that has been fundamental to develop practical Non-Interactive Zero-Knowledge (NIZK) proofs. On the theoretical side, we explore how efficient can NIZK proofs be under weak complexity assumptions. Specifically, we reduce the cost of proofs of satisfiability of quadratic equations, we define a new commitment scheme that is compatible with other pairing-based NIZK arguments, and we construct a simulation-sound argument that results in a new a signature of knowledge with communication sublinear in the circuit size under standard assumptions. Additionally, we study how to reduce the cost of verification in one of the most widely deployed NIZK arguments in practice.
For the podcast associated with this article, please visit https://academic.oup.com/eurheartj/pages/Podcasts. This Focus Issue on arrhythmias contains a Special Article contribution entitled ‘1970–2020: 50 years of research on the long QT syndrome—from almost zero knowledge to precision medicine’, authored by Peter Schwartz from the IRCCS in Milan, Italy.1 A lot has been written about the long QT syndrome (LQTS) and there is a wealth of traditional reviews summarizing the existing knowledge on epidemiology, pathogenesis, clinical presentation, and the state of genetic testing.2,3 However, this Special Article is very special indeed. Professor Schwartz notes that those involved in clinical research rarely begin working on a rather obscure disease, still largely unexplored, following its ripening into a medical entity of great interest to clinicians and basic scientists alike, and to do so for exactly 50 years. This is what has been Professor Schwartz’s privilege in the relentless pursuit of the intriguing disease known as LQTS. This essay begins with the encounter with his first patient affected by LQTS when just a handful of cardiologists had seen similar cases, and continues with the series of efforts which eventually led—together with many brilliant partners and associates—to the description and understanding of the natural history of the disease and the most effective therapies. It then touches on how the International Registry for LQTS, with its well-documented family trees, constituted the necessary springboard for the major genetic discoveries of the 1990s. From the explosion of genetic data, his own interest focused first on the intriguing genotype–phenotype correlation and then on ‘modifier genes’, in an attempt to understand why family members with the same disease-causing mutation may have an opposite clinical history; and from there on to induced pluripotent stem cell (iPS)-derived cardiomyocytes, used for unravelling the specific mechanisms of action of modifier genes and for exploring novel therapeutic strategies. This long, and highly rewarding, journey continues because the fascination with and the attraction of the unknown is irresistible. Brugada syndrome (BrS) was first described as a primary electrical disorder predisposing to sudden cardiac death (SCD) by the Brugada brothers, although its eponymous title was only bestowed 4 years later. Eight patients had demonstrated an electrocardiogram (ECG) pattern of ‘right bundle branch block, normal QT interval and persistent ST-segment elevation in precordial leads V1 to V2–V3 not explainable by electrolyte disturbances, ischaemia or structural heart disease’.4 In a State of the Art Review article entitled ‘Brugada syndrome and reduced right ventricular outflow tract conduction reserve: a final common pathway?’, Elijah Behr from St George’s University of London in the UK, and colleagues5 note that BrS was first described as a primary electrical disorder predisposing to the risk of SCD and characterized by right precordial lead ST elevation. Then, early descriptions of right ventricular structural abnormalities and of right ventricular outflow tract (RVOT) conduction delay in BrS patients set the stage for the current controversy over the pathophysiology underlying the syndrome: channelopathy or cardiomyopathy; repolarization or depolarization. This review examines the current understanding of the BrS substrate, its genetic and non-genetic basis, theories of pathophysiology, and the clinical implications thereof. The authors propose that the final common pathway for BrS could be viewed as a disease of ‘reduced RVOT conduction reserve’ (Figure 1). Brugada syndrome (BrS) as a disease of impaired right ventricular outflow tract (RVOT) conduction reserve. Normally, intrinsic RVOT conduction reserve may be affected by a patient’s age and gender. In BrS, cellular and tissue abnormalities cause a reduction in RVOT conduction reserve: genetic abnormalities, whether mediated by a pathogenic SCN5A variant, an increased BrS-PRS, and/or additional genetic insults, may have direct effects on Nav1.5, as well as tissue effects causing RVOT inflammation, fibrosis, and gap junction abnormalities. Decreased Nav1.5 current, together with electrical discontinuity caused by RVOT structural changes, converges to disrupt normal depolarization, with or without secondary repolarization effects, leading to impairment of the conduction reserve of the RVOT. In this framework, the marginal conduction reserve can be exposed by acute modulators such as fever, drugs, and altered vagal tone which further impair conduction and expose the Brugada phenotype (from Behr ER, Ben-Haim Y, Ackerman MJ, Krahn AD, Wilde AAM. Brugada syndrome and reduced right ventricular outflow tract conduction reserve: a final common pathway? See pages 1073–1081). Brugada syndrome (BrS) as a disease of impaired right ventricular outflow tract (RVOT) conduction reserve. Normally, intrinsic RVOT conduction reserve may be affected by a patient’s age and gender. In BrS, cellular and tissue abnormalities cause a reduction in RVOT conduction reserve: genetic abnormalities, whether mediated by a pathogenic SCN5A variant, an increased BrS-PRS, and/or additional genetic insults, may have direct effects on Nav1.5, as well as tissue effects causing RVOT inflammation, fibrosis, and gap junction abnormalities. Decreased Nav1.5 current, together with electrical discontinuity caused by RVOT structural changes, converges to disrupt normal depolarization, with or without secondary repolarization effects, leading to impairment of the conduction reserve of the RVOT. In this framework, the marginal conduction reserve can be exposed by acute modulators such as fever, drugs, and altered vagal tone which further impair conduction and expose the Brugada phenotype (from Behr ER, Ben-Haim Y, Ackerman MJ, Krahn AD, Wilde AAM. Brugada syndrome and reduced right ventricular outflow tract conduction reserve: a final common pathway? See pages 1073–1081). Since its description, BrS has been the subject of increased scientific interest as a cause of SCD due to ventricular tachycardia/fibrillation in young and otherwise healthy individuals. BrS is believed to be a genetic disease, although the majority of clinically confirmed cases lack molecular validation, due to our current shortfall of understanding of the genetics of this syndrome.6,7 Despite SCN5A being the most commonly known mutated gene to date, the genotype–phenotype relationship is poorly understood and remains uncertain. In a clinical research article entitled ‘Brugada syndrome genetics is associated with phenotype severity’, Giuseppe Ciconte from the IRCCS Policlinico San Donato in Italy, and colleagues aimed to elucidate the genotype–phenotype correlation in BrS.8 BrS probands deemed at high risk of future arrhythmic events underwent genetic testing and phenotype characterization by means of epicardial arrhythmogenic substrate mapping and were allocated to two groups according to the presence or absence of the SCN5A mutation. Two hundred probands (mean age 43 years) were included in this study. SCN5A-positive patients exhibited a larger epicardial arrhythmogenic substrate area, more prolonged ECGs, and more frequently late potentials at non-invasive testing (Figure 2). The presence of an SCN5A mutation explained >26% of the variation in the epicardial arrhythmogenic substrate area and was the strongest predictor of a larger epicardial arrhythmogenic area. Brugada syndrome phenotypic expression predictors. (A) Large Brugada syndrome epicardial substrate in a male patient with spontaneous type 1 electrocardiogram pattern experiencing appropriate implantable cardioverter-defibrillator therapy. (B) Specific contribution of each variable (SCN5A mutations, spontaneous type 1 electrocardiogram pattern, and gender), in explaining the variance of the arrhythmogenic substrate. (C) Receiver-operating characteristic curve analysis demonstrating the accuracy of the model for the prediction of a large arrhythmogenic substrate (≥6.3 cm2) (from Ciconte G, Monasky MM, Santinelli V, Micaglio E, Vicedomini G, Anastasia L, Negro G, Borrelli V, Giannelli L, Santini F, de Innocentiis C, Rondine R, Locati ET, Bernardini A, Mazza BC, Mecarocci V, Calović Ž, Ghiroldi A, D’Imperio S, Benedetti S, Di Resta C, Rivolta I, Casari G, Petretto E, Pappone C. Brugada syndrome genetics is associated with phenotype severity. See pages 1082–1090). Brugada syndrome phenotypic expression predictors. (A) Large Brugada syndrome epicardial substrate in a male patient with spontaneous type 1 electrocardiogram pattern experiencing appropriate implantable cardioverter-defibrillator therapy. (B) Specific contribution of each variable (SCN5A mutations, spontaneous type 1 electrocardiogram pattern, and gender), in explaining the variance of the arrhythmogenic substrate. (C) Receiver-operating characteristic curve analysis demonstrating the accuracy of the model for the prediction of a large arrhythmogenic substrate (≥6.3 cm2) (from Ciconte G, Monasky MM, Santinelli V, Micaglio E, Vicedomini G, Anastasia L, Negro G, Borrelli V, Giannelli L, Santini F, de Innocentiis C, Rondine R, Locati ET, Bernardini A, Mazza BC, Mecarocci V, Calović Ž, Ghiroldi A, D’Imperio S, Benedetti S, Di Resta C, Rivolta I, Casari G, Petretto E, Pappone C. Brugada syndrome genetics is associated with phenotype severity. See pages 1082–1090). The authors conclude that in BrS, the genetic background is the main determinant for the extent of the electrophysiological abnormalities. SCN5A mutation carriers exhibit more pronounced epicardial electrical abnormalities and a more aggressive clinical presentation. These results contribute to the understanding of the genetic determinants of the phenotypic expression of BrS and provide possible explanations for the varying degrees of disease expression. The manuscript is accompanied by an Editorial by Connie R. Bezzina from the AMC Heart Center in Amsterdam, the Netherlands, and colleagues.9 The authors note that while we are still at the early stages of being able to offer individualized prognosis for BrS patients, studies like that of Ciconte and colleagues are beginning to illuminate the path between genetic risk factors and clinical outcomes. Although COVID-19 manifests primarily as a severe respiratory infection, numerous studies demonstrate that cardiovascular complications are common, and pre-existing cardiovascular conditions are predictors of survival in COVID-19.10–12 The first cases of COVID-19 in Sweden were reported in early February 2020. The Swedish Public Health Authority declared community spread in Sweden on 16 March. As a consequence, updated guidelines from the European Resuscitation Council (ERC) and the Swedish Resuscitation Council recommended that bystanders should avoid ventilation and focus their resuscitation attempts on chest compressions only in the case of suspected COVID-19.13 In a clinical research article entitled ‘Cardiac arrest in COVID-19: characteristics and outcomes of in- and out-of-hospital cardiac arrest. A report from the Swedish Registry for Cardiopulmonary Resuscitation’, Pedram Sultanian from the University of Gothenburg in Sweden, and colleagues investigated characteristics and outcomes among cardiac arrest cases with COVID-19 and differences between the pre-pandemic and the pandemic period in out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA).14 The authors included all patients reported to the Swedish Registry for Cardiopulmonary Resuscitation from anuary to July 2020. Sultanian et al. enrolled ∼2000 cases of OHCA and 1000 cases of IHCA. During the pandemic, 10.0% of OHCAs and 16.1% of IHCAs had ongoing COVID-19 with regards to OHCA. Adjusted 30-day survival was 4.7% for patients with COVID-19, 9.8% for patients without COVID-19, and 7.6% in the pre-pandemic period (P = 0.03) with regards to IHCA. Adjusted 30-day survival was 23.1% in COVID-19-positive cases, 39.5% in patients without COVID-19, and 36.4% in the pre-pandemic period (P = 0.04). The authors conclude that this is, to the best of their knowledge, the most detailed report on characteristics and outcome in COVID-19 patients suffering cardiac arrest within and beyond the hospital perimeter, and that they report a number of unexpected findings, many of which highlight the severity of COVID-19 and the potential shift in the epidemiology of cardiac arrest brought about by this pandemic. The manuscript is accompanied by an Editorial by Xavier Jouven from the Université de Paris in France, and colleagues.15 The authors note that these findings highlight the importance of anticipation and planning in the management of healthcare crises. The observations with respect to the COVID-19 pandemic and cardiac arrest should serve as an important wake-up call for healthcare systems worldwide to develop blueprints and contingency plans for preparedness in the case of such eventualities. With improvements in pharmacological and device therapy, earlier and more aggressive cardiovascular prevention, and prompt coronary intervention, there has been a gradual and substantial reduction in SCD risk over the last two decades in patients with heart failure. Thus, one may even reasonably speculate whether the results of randomized trials on implantable cardioverter-defibrillators (ICDs) would be the same if conducted in the current era of heart failure management,16,17 as the evidence supporting guideline recommendations for ICDs dates from the late 1990s and early 2000s.18 There is a particular need to revisit the current status of routine primary prevention ICD implantation in women. This issue contains a Viewpoint article entitled ‘Time to revisit implantable cardioverter-defibrillator implantation criteria in women’ by Sérgio Barra from the Hospital da Luz Arrábida in Portugal, and colleagues.19 The authors note that the low level of participation of female patients in ICD trials is a long-standing problem, but physicians and guidelines continue to extrapolate from results derived mainly from men to recommend routine ICD implantation in women despite lack of clear proof of a reduction in mortality. Conversely, the benefit of an ICD in men may have been relatively underestimated when looking at the data in total. It is evident that the data being used for decision-making are both outdated and also weak with respect to potential benefit in women. Hence it can be strongly argued that true equipoise exists for new, well-designed randomized trials assessing the efficacy of primary prevention ICDs, particularly in female patients, in conjunction with current heart failure therapies. The issue is also complemented by two Discussion Forum contributions. In an article entitled ‘Prognostication after out-of-hospital cardiac arrest: biases and caveats’, Andrew Williams from the King’s College Hospital in London, UK and colleagues comment on the recent publication entitled ‘A practical risk score for early prediction of neurological outcome after out-of-hospital cardiac arrest: MIRACLE2’ by Nilesh Pareek from the King’s College Hospital NHS Foundation Trust in the UK, and colleagues.20,21 Pareek and colleagues respond in a separate contribution.22 The editors hope that readers of this issue of the European Heart Journal will find it of interest. With thanks to Amelia Meier-Batschelet, Johanna Huggler, and Martin Meyer for help with compilation of this article.
The development of blockchain has put forward higher requirements for authentication technology. In order to solve the current blockchain authentication problem and enhance the supervision and anonymity, we propose an authentication scheme based on master-slave certificate and zero-knowledge proof. Users can hide their real identity information through the anonymity of the slave certificate. When necessary, regulators can track the malicious users through smart contracts. Through security analysis, it is verified that there is no linkability between the master and slave certificates of this scheme, which can efficiently achieve supervisable anonymous authentication. The simulation experiment results show that the scheme is stable and scalable. The results also show that, compared with the traditional authentication, this scheme reduces the computational overhead of certificate issuers and is suitable for adoption in blockchain systems.
Zero-knowledge succinct non-interactive argument of knowledge (zkSNARK) allows a party, known as the prover, to convince another party, known as the verifier, that he knows a private value $v$, without revealing it, such that $F(u,v)=y$ for some function $F$ and public values $u$ and $y$. There are various versions of zk-SNARK, among them, Quadratic Arithmetic Program (QAP)-based zk-SNARK has been widely used in practice, specially in Blockchain technology. This is attributed to two desirable features; its fixed-size proof and the very light computation load of the verifier. However, the computation load of the prover in QAP-based zkSNARKs, is very heavy, even-though it is designed to be very efficient. This load can be beyond the prover's computation power to handle, and has to be offloaded to some external servers. In the existing offloading solutions, either (i) the load of computation, offloaded to each sever, is a fraction of the prover's primary computation (e.g., DZIK), however the servers need to be trusted, (ii) the servers are not required to be trusted, but the computation complexity imposed to each one is the same as the prover's primary computation (e.g., Trinocchio). In this paper, we present a scheme, which has the benefits of both solutions. In particular, we propose a secure multi-party proof generation algorithm where the prover can delegate its task to $N $ servers, where (i) even if a group of $T \in \mathbb{N}$ servers, $T\le N$, collude, they cannot gain any information about the secret value $v$, (ii) the computation complexity of each server is less than $1/(N-T)$ of the prover's primary computation. The design is such that we don't lose the efficiency of the prover's algorithm in the process of delegating the tasks to external servers.