Revisiting the Feasibility of Public Key Cryptography in Light of IIoT Communications

Digital certificates are regarded as the most secure and scalable way of implementing authentication services in the Internet today. They are used by most popular security protocols, including Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS). The lifecycle management of digital certificates relies on centralized Certification Authority (CA)-based Public Key Infrastructures (PKIs). However, the implementation of PKIs and certificate lifecycle management procedures in Industrial Internet of Things (IIoT) environments presents some challenges, mainly due to the high resource consumption that they imply and the lack of trust in the centralized CAs. This paper identifies and describes the main challenges to implement certificate-based public key cryptography in IIoT environments and it surveys the alternative approaches proposed so far in the literature to address these challenges. Most proposals rely on the introduction of a Trusted Third Party to aid the IIoT devices in tasks that exceed their capacity. The proposed alternatives are complementary and their application depends on the specific challenge to solve, the application scenario, and the capacities of the involved IIoT devices. This paper revisits all these alternatives in light of industrial communication models, identifying their strengths and weaknesses, and providing an in-depth comparative analysis.

When Measurements Meet Blockchain: On Behalf of an Inter-NMI Network

The growing demand for solutions related to measurement (e.g., digital sensors, smart meters, distributed measuring systems) imposes several concerns about information and process reliability. In this context, blockchain can play a crucial role as a platform to implement applications and activities in the context of legal metrology. In most countries, the National Metrology Institutes (NMIs) are responsible for promoting these initiatives. Thus, in this paper, we present a functional architecture to integrate NMIs in a collaborative blockchain network. We discuss the main aspects and features that an inter-NMI blockchain network must deliver. Furthermore, we implement our proposal using the Hyperledger Fabric platform. We connect peers from Physikalisch-Technische Bundesanstalt (PTB) (German NMI) and the National Institute of Metrology, Quality, and Technology (Inmetro) (Brazilian NMI) in a useful application that consists of a blockchain-based public-key infrastructure to identify and authenticate smart meters. Our preliminary results demonstrate that the proposed architecture meets the main requirements imposed by applications involving measurements. Furthermore, it opens the opportunity to integrate NMIs from other countries into the project, constituting an important global initiative in the metrology field.

Non-Invertible Public Key Certificates

Post-quantum public cryptosystems introduced so far do not define a scalable public key infrastructure for the quantum era. We demonstrate here a public certification system based on Lizama’s non-invertible key exchange protocol which can be used to implement a secure, scalable, interoperable and efficient public key infrastructure (PKI). We show functionality of certificates across different certification domains. Finally, we discuss a method that enables non-invertible certificates to exhibit perfect forward secrecy (PFS).

Osteonecrosis of the jaws associated with protein kinase inhibitors: a systematic review

This systematic review analysed evidence relating to medication-related osteonecrosis of the jaws (MRONJ) associated with protein kinase inhibitors in antiresorptive naïve patients. A literature search of major biomedical databases was conducted in March 2020. Information extracted from relevant articles included bibliographic information, patient characteristics, MRONJ characteristics at diagnosis, management strategies and outcomes. Sixteen studies, representing data from 17 patients, were included for final analysis. Descriptive statistics were used to synthesis available data. Eleven protein kinase inhibitors were implicated, with a mean exposure of 13 months prior to MRONJ. Renal cell carcinoma was the primary diagnosis in 41.2% of patients. Patient symptoms, clinical features, radiographic findings and histological findings were consistent with those previously described in patients with MRONJ associated with antiresorptive medications. Overall, there was a 75% rate of cure, with a mean healing time of 17.2 weeks. Patients were treated surgically in 53.3% of the cases. Patients treated surgically achieved complete healing in 100% of cases, compared with 58% in those treated conservatively. Drug discontinuation was reported in 69.2% of patients. Patients who had the offending drug discontinued achieved complete healing in 75% of cases, compared with 50% in those who did not. Evidence relating to MRONJ associated with protein kinase inhibitors is of low quality. From the available data, there are notable differences relating to patient characteristics, treatment strategies and outcomes, between MRONJ associated with protein kinase inhibitors compared with antiresorptives. Higher quality evidence is required to support the findings of this review.

Protein kinase A inhibitor proteins (PKIs) divert GPCR-Gαs-cAMP signaling toward EPAC and ERK activation and are involved in tumor growth

The PKA-inhibitor (PKI) family members PKIα, PKIβ, and PKIγ bind with high affinity to PKA and block its kinase activity, modulating the extent, and duration of PKA-mediated signaling events. While PKA is a well-known regulator of physiological and oncogenic events, the role of PKI proteins in these pathways has remained elusive. Here, by measuring activation of the MAPK pathway downstream of GPCR-Gαs-cAMP signaling, we show that the expression levels of PKI proteins can alter the balance of activation of two major cAMP targets: PKA and EPAC. Our results indicate that PKA maintains repressive control over MAPK signaling as well as a negative feedback on cAMP concentration. Overexpression of PKI and its subsequent repression of PKA dysregulates these signaling pathways, resulting in increased intracellular cAMP, and enhanced activation of EPAC and MAPK. We also find that amplifications of PKIA are common in prostate cancer and are associated with reduced progression free survival. Depletion of PKIA in prostate cancer cells leads to reduced migration, increased sensitivity to anoikis and reduced tumor growth. By altering PKA activity PKI can act as a molecular switch, driving GPCR-Gαs-cAMP signaling toward activation of EPAC-RAP1 and MAPK, ultimately modulating tumor growth.

A Stapled Peptide Mimic of the Pseudosubstrate Inhibitor PKI Inhibits Protein Kinase A

Kinases regulate multiple and diverse signaling pathways and misregulation is implicated in a multitude of diseases. Although significant efforts have been put forth to develop kinase-specific inhibitors, specificity remains a challenge. As an alternative to catalytic inhibition, allosteric inhibitors can target areas on the surface of an enzyme, thereby providing additional target diversity. Using cAMP-dependent protein kinase A (PKA) as a model system, we sought to develop a hydrocarbon-stapled peptide targeting the pseudosubstrate domain of the kinase. A library of peptides was designed from a Protein Kinase Inhibitor (PKI), a naturally encoded protein that serves as a pseudosubstrate inhibitor for PKA. The binding properties of these peptide analogs were characterized by fluorescence polarization and surface plasmon resonance, and two compounds were identified with K_D values in the 500-600 pM range. In kinase activity assays, both compounds demonstrated inhibition with 25-35 nM IC₅₀ values. They were also found to permeate cells and localize within the cytoplasm and inhibited PKA activity within the cellular environment. To the best of our knowledge, these stapled peptide inhibitors represent some of the highest affinity binders reported to date for hydrocarbon stapled peptides.

Distributed One Time Password Infrastructure for Linux Environments

Nowadays, there is a lot of critical information and services hosted on computer systems. The proper access control to these resources is essential to avoid malicious actions that could cause huge losses to home and professional users. The access control systems have evolved from the first password based systems to the modern mechanisms using smart cards, certificates, tokens, biometric systems, etc. However, when designing a system, it is necessary to take into account their particular limitations, such as connectivity, infrastructure or budget. In addition, one of the main objectives must be to ensure the system usability, but this property is usually orthogonal to the security. Thus, the use of password is still common. In this paper, we expose a new password based access control system that aims to improve password security with the minimum impact in the system usability.

Secure and Authenticated Data Communication in Wireless Sensor Networks

Securing communications in wireless sensor networks is increasingly important as the diversity of applications increases. However, even today, it is equally important for the measures employed to be energy efficient. For this reason, this publication analyzes the suitability of various cryptographic primitives for use in WSNs according to various criteria and, finally, describes a modular, PKI-based framework for confidential, authenticated, secure communications in which most suitable primitives can be employed. Due to the limited capabilities of common WSN motes, criteria for the selection of primitives are security, power efficiency and memory requirements. The implementation of the framework and the singular components have been tested and benchmarked in our testbed of IRISmotes.

PKA catalytic subunit compartmentation regulates contractile and hypertrophic responses to β-adrenergic signaling

β-Adrenergic signaling is spatiotemporally heterogeneous in the cardiac myocyte, conferring exquisite control to sympathetic stimulation. Such heterogeneity drives the formation of protein kinase A (PKA) signaling microdomains, which regulate Ca(2+) handling and contractility. Here, we test the hypothesis that the nucleus independently comprises a PKA signaling microdomain regulating myocyte hypertrophy. Spatially-targeted FRET reporters for PKA activity identified slower PKA activation and lower isoproterenol sensitivity in the nucleus (t50=10.6±0.7 min; EC50=89.0 nmol/L) than in the cytosol (t50=3.71±0.25 min; EC50=1.22 nmol/L). These differences were not explained by cAMP or AKAP-based compartmentation. A computational model of cytosolic and nuclear PKA activity was developed and predicted that differences in nuclear PKA dynamics and magnitude are regulated by slow PKA catalytic subunit diffusion, while differences in isoproterenol sensitivity are regulated by nuclear expression of protein kinase inhibitor (PKI). These were validated by FRET and immunofluorescence. The model also predicted differential phosphorylation of PKA substrates regulating cell contractility and hypertrophy. Ca(2+) and cell hypertrophy measurements validated these predictions and identified higher isoproterenol sensitivity for contractile enhancements (EC50=1.84 nmol/L) over cell hypertrophy (EC50=85.9 nmol/L). Over-expression of spatially targeted PKA catalytic subunit to the cytosol or nucleus enhanced contractile and hypertrophic responses, respectively. We conclude that restricted PKA catalytic subunit diffusion is an important PKA compartmentation mechanism and the nucleus comprises a novel PKA signaling microdomain, insulating hypertrophic from contractile β-adrenergic signaling responses.

Mutation E169K in junctophilin-2 causes atrial fibrillation due to impaired RyR2 stabilization

OBJECTIVES

This study sought to study the role of junctophilin-2 (JPH2) in atrial fibrillation (AF).

BACKGROUND

JPH2 is believed to have an important role in sarcoplasmic reticulum (SR) Ca(2+) handling and modulation of ryanodine receptor Ca(2+) channels (RyR2). Whereas defective RyR2-mediated Ca(2+) release contributes to the pathogenesis of AF, nothing is known about the potential role of JPH2 in atrial arrhythmias.

METHODS

Screening 203 unrelated hypertrophic cardiomyopathy patients uncovered a novel JPH2 missense mutation (E169K) in 2 patients with juvenile-onset paroxysmal AF (pAF). Pseudoknock-in (PKI) mouse models were generated to determine the molecular defects underlying the development of AF caused by this JPH2 mutation.

RESULTS

PKI mice expressing E169K mutant JPH2 exhibited a higher incidence of inducible AF than wild type (WT)-PKI mice, whereas A399S-PKI mice expressing a hypertrophic cardiomyopathy-linked JPH2 mutation not associated with atrial arrhythmias were not significantly different from WT-PKI. E169K-PKI but not A399A-PKI atrial cardiomyocytes showed an increased incidence of abnormal SR Ca(2+) release events. These changes were attributed to reduced binding of E169K-JPH2 to RyR2. Atrial JPH2 levels in WT-JPH2 transgenic, nontransgenic, and JPH2 knockdown mice correlated negatively with the incidence of pacing-induced AF. Ca(2+) spark frequency in atrial myocytes and the open probability of single RyR2 channels from JPH2 knockdown mice was significantly reduced by a small JPH2-mimicking oligopeptide. Moreover, patients with pAF had reduced atrial JPH2 levels per RyR2 channel compared to sinus rhythm patients and an increased frequency of spontaneous Ca(2+) release events.

CONCLUSIONS

Our data suggest a novel mechanism by which reduced JPH2-mediated stabilization of RyR2 due to loss-of-function mutation or reduced JPH2/RyR2 ratios can promote SR Ca(2+) leak and atrial arrhythmias, representing a potential novel therapeutic target for AF.